IPM practitioner Joe Barcinas with IPM researcher Joseph Morse

Transcription

CITRUS RESEARCH BOARD, P.O. Box 230, Visalia, CA 93279
Address Service Requested
PRSRT STD
U.S. POSTAGE PAID
PONTIAC, IL 61764
PERMIT 125
IPM practitioner
Joe Barcinas
with IPM researcher
Joseph Morse
Citrograph
Citrograph
March/April 2012
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CRP0112MOVENT0222-R00
Citrograph
MARCH/APRIL 2012 • Volume 3 • Number 2
An Official Publication of the Citrus Research Board
Cover photo by Iqbal Pittalwala, UC Riverside
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4 Editorial
6 CCM Showcase, Protecting our Future
10 Industry Views
12 Proper monitoring and management
of California Red Scale in the San Joaquin Valley
22 Management of citrus thrips to reduce the evolution of resistance
32 The evolution of biologically-based
Integrated Pest Management in
California citrus: history and perspective
44 What are the University of California
sources for citrus integrated pest management information?
48 CRB 2011Annual Report 50 California Citrus Spurred Colonization–
Aided Through the University of California...
54 Reagentless detection of citrus pathogens
using differential mobility spectrometry
58 Celebrating Citrus
Citrograph is published bimonthly by the Citrus Research Board, 217 N. Encina, Visalia, CA 93291. Citrograph is sent to all
California citrus producers courtesy of the Citrus Research Board. If you are currently receiving multiple copies, or would like
to make a change in your Citrograph subscription, please contact the publication office (above, left).
Every effort is made to ensure accuracy in articles published by Citrograph; however, the publishers assume no responsibility
for losses sustained, allegedly resulting from following recommendations in this magazine. Consult your local authorities.
The Citrus Research Board has not tested any of the products advertised in this publication, nor has it verified any of the
statements made in any of the advertisements. The Board does not warrant, expressly or implicitly, the fitness of any product
advertised or the suitability of any advice or statements contained herein.
March/April 2012 Citrograph 3
EDITORIAL
BY TED A. BATKIN, President, Citrus Research Board Don’t let the background noise drown out the music
This again shows how
important it is to work
with accurate information
and how important a
good communications
system is in providing
growers accurate,
up-to-date information.
4 Citrograph March/April 2012
I
n a previous life, I studied classical music and received a BA degree
in conducting. One of the jobs of the conductor is to separate out
the noise from the true music and bring all the musicians together
to produce a harmonic sound.
It is the same today in life as we attempt to keep focused on the
true mission of the research and development programs for the California citrus growers. All too often, this effort is clouded by background noise from sectors with their own agendas and priorities.
Such is the case with the recent reporting of an ACP in a trap in the
San Joaquin Valley. The background noise in this event was deafening,
and the true picture of what actually happened became drowned out
in a myriad of false reports from many sectors in the media.
In truth, there was a portion of an ACP found sticking to a trap
from the glassy-winged sharpshooter program. The piece was DNA
tested and found to be an Asian citrus psyllid. This event triggered action by CDFA to provide delimitation trapping grids and tree-by-tree
ground surveys to determine if a breeding population existed in the
area. When the additional efforts came up negative, the Department
correctly identified the find as a “Regulatory Event” and closed the
book on the issue. Delimitation will continue in the area, but no further quarantine action will take place.
This event should serve as a reminder of just how vulnerable we
are to specific actions. First, it proved the value of the constant trapping program being conducted by the industry in the commercial
areas of the state to serve as an early warning system of ACP populations. The fact that there had not been any previous ACP detections played into the decision process to determine a potential
quarantine.
Second, it shows how easy it could be for an ACP to move into
the San Joaquin Valley and how we need to be sure to have adequate contingency plans for ACP populations in the area. Do
you have your plan in place???
Finally, it again shows how important it is to work with accurate information and how important a good communications
system is in providing growers accurate, up-to-date information
when a true infestation occurs. The industry will continue to develop better systems for informing all growers of the threat and any
actual ACP populations that are detected, including what to do and
how to do it.
Your industry leaders are constantly working on this through all of
the organizations that serve the growers. Just remember to sort out all
the background noise and listen for the real music. l
The Mission of the Citrus Research Board:
Develop knowledge and build systems for grower vitality.
Focus on quality assurance, clonal protection, production research,
variety development, and grower/public education.
CITRUS RESEARCH BOARD MEMBER LIST BY DISTRICT 2011-2012
District 1 – Northern California
District 3 – California Desert
Member
Allan Lombardi, Exeter Donald Roark, Lindsay Jim Gorden, Exeter Joe Stewart, Bakersfield
Etienne Rabe, Bakersfield
John Richardson, Porterville
Kevin Olsen, Pinedale Member
Mark McBroom, Calipatria
Public Member
Member
Seymour Van Gundy, Riverside
Alternate
Justin Brown, Orange Cove
Dan Dreyer, Exeter
Dan Galbraith, Porterville
Franco Bernardi, Visalia
Richard Bennett, Visalia
Jeff Steen, Strathmore
Tommy Elliott, Visalia
District 2 – Southern California – Coastal
Member
Earl Rutz, Pauma Valley
William Pidduck, Santa Paula
Joe Barcinas, Riverside Alternate
Alan Washburn, Riverside
James Finch, Santa Paula
Warren Lyall, Pauma Valley
Alternate
Craig Armstrong, Thermal
Alternate Steve Garnsey, Fallbrook
Citrus Research Board
217 N Encina, Visalia, CA 93291
PO Box 230, Visalia, CA 93279
(559) 738-0246
FAX (559) 738-0607
E-Mail [email protected]
CALENDAR
May 2 CRB/CPDPP Joint Operations Committee Meeting
CRB Conference Room – Visalia
May 2
CPDPP Outreach Subcommittee Meeting
CRB Conference Room – Visalia
June 28
CRB Board Meeting
Four Points by Sheraton – Ventura
August 21-23
CRB Research – Review of Proposals
DoubleTree Hotel – Bakersfield
September 18 CRB Annual Meeting
Lindcove REC
October 10-11 California Citrus Conference
Porterville Fairgrounds – Porterville
November 1
CCM Annual Meeting
For more information on the above, contact the CRB office at
(559) 738-0246.
DO YOU KNOW...?
What happened in California 40 years ago that
still impacts pest management operations today?
(Turn to the inside back cover for the answer.)
‘We are laying out our unified plan
to control the disease’
We need to be ready
and will be.
—Robert Leavitt
Photo by Lynn Sanderson
Editor’s Note: The following message from CDFA’s Dr. Robert Leavitt is a
digest of the remarks he made at the 2012 Citrus Showcase, where he was a luncheon speaker and workshop panelist.
A storm is coming to California citrus—huanglongbing (HLB), or citrus
greening. History tells us it’s just a matter of time before the disease is detected
here. It has always followed its vector, the Asian citrus psyllid, which has been
in California since 2008.At the moment, we know HLB is inching closer after
detections in Baja California, Mexico, and Texas.
So we believe that, sooner or later, HLB will be here. Under the leadership
of California Department of Food and Agriculture Secretary Karen Ross, we
are laying out our unified plan to control the disease when the time comes. The
need to protect citrus groves and residential trees is paramount. We are acutely
aware of the risk to fresh and export markets and are doing all that is possible
to secure those markets.
Working with the USDA, local Ag Commissioners, the Citrus Research
Board, and the federal office of Customs and Border Protection, and utilizing
the best scientific and technical advice available, CDFA is presenting a plan
with several key points:
1). Screen citrus mother trees so clean, disease-free stock may be planted.
2). Use robust surveying and detection in harmony with quarantine regulations to restrict the movement of host material.
3). Control, suppress and, where possible, eradicate psyllids.
4). Area-wide treatment programs in both residential and commercial citrus.
5). Removal of residential and commercial trees infected with HLB.
This is the greatest challenge California’s citrus industry will face. We need
to be ready and will be. We appreciate your support as we all move forward
together in a program that is a model for public-private cooperation.
Robert Leavitt, Ph.D., is Director of the California Department of Food
and Agriculture’s Plant Health Division. l
CCM’s 2012 Citrus Showcase
‘Protecting our citrus, protecting our future’
O
n March 8, hundreds of growers along with packers and other members of the industry converged
on the Visalia Convention Center for California Citrus
Mutual’s Citrus Showcase.
“Protecting our citrus, protecting our future” was the
theme for this Showcase, and at no time during the day
was that theme more appropriate than at the luncheon
when Dr. Robert Leavitt of CDFA addressed the crowd
on the subject of Asian citrus psyllid and huanglongbing.
(See ‘laying out our unified plan’ above.)
The audience also heard from attorney and ag advocate George Soares, managing partner of Kahn, Soares
& Conway, who gave an update on State politics, offered
insights into the “personality” of Sacramento, and shared
thoughts on becoming more effective in dealings with
government given today’s political climate.
The program included three workshops, each with a
panel presentation and then follow-up Q&A, on meeting
food safety requirements and expectations, evaluating
the impact of this season’s frost events (especially the toll
on mandarins), and the latest information on ACP/HLB.
The trade show portion of the event had 70 exhibitors including the Citrus Research Board and the CPDPP. Sponsors of the 2012 Citrus Showcase were Bayer
Crop Science, Dow AgroSciences, Farm Credit Associations, Fruit Growers Supply Company, Sinclair Systems
International, Southern California Edison, Syngenta
Crop Protection, Valent USA, and Yara North America.
The workshops were sponsored by Amvac Chemical
Corporation and Capital Agricultural Property Services,
Inc., and the continental breakfast was hosted by Mary
Roach Insurance. l
ABOUT THE COVER
F
or the cover of this issue featuring Integrated Pest Management, we chose orange grower and CRB Board member Joe Barcinas, who operates an insectary and is a pest
control advisor, and research entomologist Dr. Joseph Morse,
professor in the Department of Entomology at UC Riverside,
whose work is focused on pests of citrus and avocado.
Shown here is the Morse lab team, left to right (with their
years in the lab in parentheses): 40%-time administrative
specialist Heavenly Clegg (18), Morse, lab assistant Pam Watkins (30, retiring June 2012), SRA Alan Urena (33), and SRA
Lindsay Robinson (28). Clegg and Watkins are holding a tray
of waxed lemons used for armored scale colonies.
Barcinas, who is based in Riverside, has worked for over
25 years as a PCA and IPM practitioner for Entomological
Services, Inc. Today, Joe and fellow PCA Robert Walther are
business partners in ESI and also as navel growers in the San
Joaquin Valley. Barcinas is also the owner of Foothill Agricultural Research, Inc. in Corona, producing Aphytis melinus,
Anagyrus pseudococci, Cryptolaemus, decollate snails, and
brown lacewing.
Photo by Iqbal Pittalwala, UC Riverside.
Getting to the core of the matter
CRB research program implements ‘Core Programs’
MaryLou Polek
A
nyone who has ever attended the March meetings
at which scientists present the progress made on
their CRB-funded research projects knows how mentally
draining these few days are. Furthermore, the time limit placed on the length of the presentations does not do
justice to our long-term programs such as the Integrated
Pest Management (IPM), breeding, and variety evaluation
programs. Despite the best efforts of Drs. Beth GraftonCardwell, Tracy Kahn, Joe Morse, and Mike Roose to interact with the Board for guidance and direction, there is
not sufficient time for the board to focus on their questions and issues.
To improve this situation, the Board and research
committee members decided to separate these extended
projects from the one- to three-year projects of limited
scope and identify them as Core Programs.
This idea was implemented during the past year. So
far, this change has been quite successful. Researchers
Beth Grafton-Cardwell and Joe Morse meet with the
Pest Management Committee, and Mike Roose and Tracy Kahn meet with the New Varieties and Development
Committee several times each year. These meetings occur
both formally in a conference room and informally in research plots.
In addition, Core Program scientists report to the industry in feature articles in the Citrograph magazine. This
issue of Citrograph features the IPM program. The September/October issue will feature articles by Mike Roose,
Tracy Kahn and Glenn Wright on breeding and evaluation
of new varieties.
Some of the advantages of this approach are that:
• It allows for greater grower input into these programs
• Growers get their questions answered more rapidly
• Research is conducted using the varieties meaningful to the grower
• Research is conducted on insect pests that are currently bothersome
• It enables the industry and researchers to identify
what problems are most important to growers
We hope this creates an environment that encourages
greater interaction and communication between the scientific community and the industry and promotes a greater
dispersal of information to the entire industry. This is another way the Citrus Research Board ensures the maximum return on the investment of grower assessment dollars in research.
Dr. MaryLou Polek is Vice President, Science & Technology, Citrus Research Board.
INDUSTRY VIEWS
asks: “What are you doing to manage/reduce/
Citrograph
minimize insect pest resistance to insecticides?”
I
manage insect pest resistance by using the principles of resistance management that reduce the selective pressure to develop resistance in the target pest
population. Management tactics include avoiding unneeded treatments by using
monitoring and economic thresholds to decide when a treatment is justified,
rotating between pesticides with different modes of action, tank mixing materials to combine modes of action, using non-chemical tactics like cultural control,
and maximizing biological control. My pest advisory work is in coastal citrus
in the counties of Ventura, Santa Barbara and San Luis Obispo. In these areas,
we are fortunate that the majority of our insect and mite pests are under fair
to excellent biological control. Generally, we get by with one or two insect/mite
sprays in a season. Citrus bud mite is the primary pest in the lemons, requiring
at least annual treatment for economic control. Also, in some production areas,
there is a complex of argentine ant provoked scales and mealybugs requiring
a broad-spectrum material every two to four years. In my region, we do have
an interesting case of treatment for one pest (citrus bud mite) leading to the
development of resistance in another pest (citrus thrips). UC Riverside has
documented resistance of citrus thrips in lemons to abamectin (Agri-Mek, etc.).
Repeated annual or biannual treatment with oil plus abamectin for bud mite
has given rise to citrus thrips resistant to abamectin. Fortunately, we have other
selective thrips materials we can rotate to treat any problem thrips populations.
And, the reliance on oil plus abamectin for bud mite control is waning as new
materials with different modes of action become available for use in citrus to
control bud mite. — Dave Machlitt, PCA and Certified Crop Advisor, Consulting Entomology Services
I
am the PCA and PCO for my family’s company, which has been in the pest
control business since 1921. Cyanide fumigation and parathion were the main
chemicals used in the early days of Integrated Pest Management. In the 1930’s,
red spider mite was introduced in California and could not tolerate temperatures
over 100 degrees, and the use of Morestan, Vendex, Omite and Plictran was
needed as the only way to go forward in Riverside and San Bernardino counties in the field of Integrated Pest Management. The red spider mite eventually
became resistant to these chemicals. The use of Sevin and Supracide was very
harsh on the beneficials; however, Lorsban has been a very rewarding tool as its
use has opened the door for many new chemicals. The introduction of Aphytis
melinus in the 1930s was a slow but promising start as the temperatures in the
Inland valleys are very good for Integrated Pest Management. The biggest test
for our future will be trying to stay focused on Integrated Pest Management in
the battle with the Asian citrus psyllid. Pyrethroids are a great control against
the Asian citrus psyllid but can also disrupt the biological control provided by
the beneficials. The use of neonicotinoids as a control system will probably be
our best source as long as resistance doesn’t ruin them. Insects will always be a
part of my history and future. — Alan A. Washburn, PCA and PCO, Washburn
& Sons, Inc.
I
have been dealing with this concern for quite a few years. When I first started
in this business (1960s), new insecticides were coming out quite regularly;
most were in the organophosphate category. We soon learned that each year
we would probably need a bigger/better “gun” for next year because of resistance. Over the years, I have always tried to minimize resistance by using the
typical ways: alternating types of products and use only when necessary. This
is not always successful; sometimes we can’t control a certain pest as well as
we would like, and we find it necessary to repeat use or fall back to a more
potent product. One of the concerns we face as pest control advisors is not
only resistance but what a product might do to the ecological balance of a
particular field. By using the proper choice of products that are now available,
hopefully we can do both. Keeping in mind our primary role is to help keep
the field as free of pests as possible and strive to maintain a balance and to
minimize resistance at the same time. It’s not always easy. I have to say that it’s
the challenge and rewards that make this something I enjoy doing. — Geary
Austin, PCA, Leffingwell Ag Sales
An invitation to the White House
An opportunity for increased exports
By Joel Nelsen
L
ate last year, Sunkist’s Mike Wootton and I received
the invitation to the White House as the President of
South Korea was coming to town for the signing of the
historic Korean Free Trade Agreement. Since it wasn’t
for beers in the Rose Garden, we chose not to attend.
On March 15 the Agreement was implemented, and
while the vast majority of the work to achieve this agreement was conducted by Mike, it is the whole industry
that could reap the benefit. It wasn’t too many years ago
that Korea was a developing market with the vast majority of tonnage shipped graded as Choice. As the citizens
of Korea and the retailers became more familiar with our
California navel orange, their taste buds demanded more
and better fruit. The industry responded, and today this
market commands premium product and at a tonnage
factor larger than any other export market.
It’s the first trade agreement in years that will benefit
the specialty crop industry and more specifically California citrus. For the past two decades, we have been on the
losing end or just not included in trade agreements. And,
for the past 20 years, the nation’s citrus imports have exploded while exports have increased very slightly and
only because our marketers have been diligent in finding
new business.
This agreement, while not perfect, can be a boon
for our sales. The obscene 54% tariff on oranges will be
phased out on fruit arriving between March 1 and August
31 with an immediate 20% reduction on landed fruit this
year. For the next six years, the tariff will be phased out
on all fruit landing in that time frame.
For fruit landing the balance of the year, a tariff will
remain at the higher level although each year 2,500 metric tons, increasing annually by 3%, will arrive duty-free.
The current 30% tariff on lemons
will be phased out over two years.
The 30% duty on grapefruit will
be phased out over five years. Not
surprisingly, the mandarin variety
is still stuck with a barrier as the
144% duty will take 15 years to be
eliminated.
Bottom line is that the importer and retailer should pass this
Mike Wootton
savings on to the Korean consumer,
thereby making the in-store California citrus that much
cheaper. Ideally, this will trigger more purchases at store
level and thus more growth for our exports in the future.
Presently, California oranges are the largest agricultural export commodity from our state. With this agreement, our position can be strengthened.
As for the beers, invite Mike over. The Bush Administration negotiators frustrated him by doing better on
other commodities since there wasn’t a competitive concern. He’s earned a sip or two. l
Proper monitoring and management
of California Red Scale in
the San Joaquin Valley
Beth Grafton-Cardwell and Jim Stewart
Editor’s Note: Work on California red
scale is now a part of the CRB’s Core
Program of Integrated Pest Management
research with Drs. Grafton-Cardwell
and Morse as lead investigators.
C
alifornia red scale has infested
citrus nearly as long as citrus
has been grown in California,
but it did not become a significant pest
of citrus in the San Joaquin Valley until
the 1970s.
All stages of California red scales
attack twigs, leaves, and fruit by drinking plant fluids with their long, threadlike mouthparts. Heavily infested fruit
may be downgraded in the packinghouse (Photo 1) and, if population levels are high, serious damage including
leaf yellowing (Photo 2) and twig dieback reduces the health and vigor of
trees.
California red scale can be managed with releases of the parasitoid
wasp Aphytis melinus (Photo 3), with
oils, with the broad spectrum organophosphate insecticides chlorpyriphos
(Lorsban) and methidathion (Supracide) and carbamates (Sevin), with
soft insecticides such as oils, the insect
growth regulators (IGRs) pyriproxyfen
(Esteem) and buprofezin (Applaud) or
with the foliar systemic lipid biosynthesis inhibitor spirotetramat (Movento).
Sometimes, California red scale
populations remain at low densities without any chemical intervention whatsoever and are managed by
the naturally occurring parasitoids
(Aphytis and Comperiella) and predators (Rhyzyobius beetles and lacewings). Sometimes they increase to
high densities because of weather or
chemical-related disruption of the natural enemies. Whatever the situation,
management efforts should be aligned
with careful monitoring of the scales
to determine pest and natural enemy
numbers.
California red scale begins its life
as a six-legged crawler that moves
away from its mother towards the end
of branches. It may crawl, or catch a
ride on an insect, or blow in the wind.
Once it settles down, if it is a female it
does not move again. If it is a male, it
does not move until it develops into a
winged adult male.
Photo 1. Fruit may be lightly infested or
heavily infested. Fruit with more than 10
scales may be downgraded in the packinghouse because these patches of scale are
noticeable.
This scale biology (Photo 4) provides us with three potential populations to monitor: winged males, crawlers, and settled stages. This article will
provide you with information as to
how best to monitor those stages for
the most effective California red scale
management.
Pheromone traps
Male scales use the pheromones
emitted by the 3rd instar female scales
to find them for mating (Photo 5). Once
mated, the female stops emitting pheromone. Males may crawl or fly to the
females. A synthetic form of the female
pheromone can be loaded onto rubber
septa (Photo 6) and placed on a paper
clip at the top of a sticky trap to attract
the males, who then become stuck on
the trap. Luckily for us, the males have
a very characteristic brown bar on their
backs that make them easy to separate
from other small insects with the aid of
a hand lens or microscope (Photo 7).
Sometimes the densities of male
scales on the traps become so numerous that it is very time consuming to
count them. Dan Moreno, USDA en-
Photo 2. Leaves heavily in- Photo 3. The adult Aphytis wasp parasitoid
fested with California red of the California red scale. Photo by Beth
scales turn yellow around the Grafton-Cardwell.
scale bodies.
tomologist, applied statistics to show
that when densities are >200 scales per
trap, you can count just the scales inside the square boxes on both sides of
the card and, because those boxes represent 20% of the surface area of the
card, multiply by 5 to get an estimate of
the total number of scales on the card
(Photo 8A).
When there are fewer than 200
scales per card (Photo 9A-C), then it
is more accurate to count scales on the
entire card, not just inside the squares.
When there are more than 2,000
scales (Photo 8B-C), then you can just
hold the card up to examples of various densities and use the photos to estimate what the density is. This greatly
reduces the time spent counting scales.
This method is much less accurate, especially since the two sides of the cards
may vary a lot in their densities, but for
cards above 2,000 scales it saves a lot
of time.
The Citrus Entomology Web site
www.ucanr.org/sites/KACCitrusEntomology/ provides examples of various
scale densities for comparison.
California red scale completes three
to four generations per year in the San
Joaquin Valley. In this region, the harsh
winters eliminate many of the younger
stages of scales, so that the population
consists primarily of late stage males
and females at the end of winter.
The first male flight occurs in
March during which mating occurs.
Approximately 550 degree-days later,
the 1st generation of crawlers emerge
from the female scale bodies. The exact
timing of these events depends on temperature. California red scale begins to
develop at temperatures above 53oF.
Degree-days for California red
scale are defined as the accumulation
of the average daily temperature (maximum temperature – minimum temperature divided by 2) above the threshold
of 53oF after the biofix of male flight.
Biofix — A point in the lifecycle of
an insect when a significant event
occurs, that can be used as a starting point. For California red scale,
the biofix of male flight is used as the
starting point to accumulate degreedays in order to predict when crawlers will emerge.
At 1,100 degree-days after the first
male flight (or 550 degree-days after
crawler emergence) another male flight
Photo 4. The lifecycle of the California red scale (drawings by G. Conville).
Photo 5. The male scale finds 3rd instar female scales and mates with them.
Courtesy UC Statewide IPM Program.
Photo 6. The pheromone trap for the
California red scale consists of a white
card, sticky on both sides, with a pheromone-impregnated lure above it.
Photo 7. A close-up of the male of
the California red scale showing the
brown bar on its back that identifies
it as a male scale.
occurs, and so on (Figure 1). When
temperatures are cool in the spring, it
takes about eight weeks to accumulate
550 degree-days (male flight to crawler
emergence). When temperatures are
hot in the summer, it only takes two to
three weeks to accumulate 550 degreedays and events happen quickly.
Pheromone traps are first placed
in the orchards in late February-early
March before the first male flight that
occurs at about March 15. Use a minimum of two traps on a 5-acre block,
four traps on a 10-acre block, six traps
on a 20-acre block, and nine traps on a
40-acre block.
You want to have at least two traps
per block, no matter how small the
block, in case one gets lost or damaged.
Hang the traps about eye level on a
sturdy branch inside the NE corner of
the tree canopy so that they are not
disturbed. The pheromone lures are
changed monthly from March through
October.
Weekly pheromone trap monitoring
It is very important to choose a
subset of your orchards and replace the
pheromone trap cards weekly to obtain
detailed information about when the
male flights are occurring. Place these
traps in a variety of orchards representing a range of temperatures (high
ground and low ground, large orchards
and small). At the Lindcove Research
and Extension Center, we see about 7
days difference in male flights between
the high ground and low ground, even
though these orchards are only a mile
apart.
For this type of pheromone trapping, use sites you don’t expect to
treat with insecticides or that had high
populations of scale the previous year
to catch enough male scales in the first
flight to be confident about the biofix.
In these orchards, an additional
monitoring tool is double sticky tape
wrapped around a green-grey twig towards the end of the branch next to
female scales (Photo 10). When the
crawlers emerge and move towards the
end of the branch, they become stuck
on the tape. Checking these tapes each
week provides added confirmation to
the degree-day calculations that crawler emergence is taking place.
Pheromone trap monitoring by flight
Photo 8. Heavy densities of male scales on pheromone cards. From left to right:
8,680 scales, 30,335 scales, and 70,845 scales per card. For these densities,
count the scales inside the square boxes on both sides of the card and multiply
times 5 to estimate their numbers or use reference cards.
Photo 9. Light densities of male scales on pheromone cards. From left to right:
230 scales, 730 scales, 2,445 scales. For cards with very low densities (less than
200 scales), count all of the scales on both sides of the card to obtain an accurate estimate. For cards with moderate densities (200 to 2,000 scales), count
the scales inside the square boxes on both sides of the card and multiply times
5 to estimate their numbers.
In the remaining orchards, use
pheromone traps to determine areas of
heavy scale infestation by leaving the
traps out during the entire flight.
• Hang the traps with a fresh
lure just before the predicted 1st, 2nd,
and 4th flights: the first flight is usually March 15, the second flight is 1,100
degree-days after the biofix of the first
male flight, and the fourth flight is 3,300
degree-days after the biofix of the first
male flight.
• Remove traps at the end of each
flight (your weekly pheromone cards
indicate when flights are declining) and
count (or estimate) scale numbers.
• Record results. These traps will
tell you which blocks and which areas
of each block have treatable infestations.
• Follow up with fruit evaluations
and then decide on a treatment plan.
In the San Joaquin Valley, citrus
growers use pheromone traps to monitor male scales during the first (May),
second (June-July), and fourth (SepOct) flights. Degree-days are used to
estimate when these flights are occurring.
The best treatment results are obtained during the 1st or 2nd generation
of scale crawler activity because the
scale populations are highly synchronized, and pesticides generally work
best on the younger instars of scales.
However, when monitoring with pheromone traps, the 1st generation male
flight is usually too low to detect more
than a few scales (Figure 1) and so it is
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centage of fruit with scale. At the same
time, you can estimate the percentage
of citrus thrips, katydid, cutworm, and
peelminer-damaged fruit.
Insecticide treatments
Treatments with most insecticides
are more effective if applied during the
1st or 2nd generation of crawlers (early
May, and late June to early July, respectively). This is because the stages of
scale are synchronized by winter mortality of younger instars in these first
two generations. Most pesticides are
more effective against the younger in-
70000
350
60000
300
50000
250
3300 DD to 4th male flight
2750 DD to 3rd crawlers
40000
200
2200 DD to 3rd male flight
30000
150
1650 DD to 2nd crawlers
1100 DD to 2rd male flight
20000
Crawlers per tape
Walk around 20 trees in each quadrant of the block, and record the number of fruit examined, the number of
fruit with scale, and the number of fruit
with noticeable patches of scales (10 or
more scales). Calculate the percentages of fruit with scale and more than 10
scales. These fruit counts will give you
an indication of whether treatments
have been effective.
Bin counts: At harvest, look at the
fruit on the surface of at least 10 bins
from areas throughout the block and
count the number of uninfested and
scale-infested fruit. Calculate the per-
No. of Male scales/trap
100
550 DD to 1 crawlers
st
50
10000
0
1-Nov
1-Oct
1-Sep
1-Aug
1-Jul
1-Jun
1-May
1-Apr
0
1-Mar
not a good predictor of whether or not
to treat; this flight is generally used just
as a biofix.
The 2nd generation flight can be a
good indicator of heavy populations.
The third flight is generally not used
because the summer heat inhibits the
flight. Most pest control advisors focus their monitoring efforts on the 4th
flight, and if it is heavy (> 1,000/trap)
and fruit is infested with scale at harvest, they plan to treat during the next
season.
The goal is to maintain California
red scale populations at levels that do
not result in more than 10 scale per
fruit at harvest because these are the
fruit that may be downgraded in the
packinghouse.
A chart was created in the 1980s
that related the male scale trap card
numbers in the 1st, 2nd and 4th flights
to the expected percentage of scale infested fruit at harvest (Figure 2). We
need to express caution when using the
chart in Figure 2 because it was created
by researchers during the organophosphate and carbamate insecticide era.
Pheromone cards are not reliable predictors of scale populations
in Aphytis-release orchards because
Aphytis prefers to parasitize female
scales, and the male scale numbers can
be very high while the female population is very low. Pheromone cards also
tend to overestimate populations that
are treated by Movento, because Movento is controlling the scales on the
fruit but not the wood. Thus, very high
male scale counts can occur in spite of
very clean fruit.
In the other direction, pheromone
cards may not be reliable predictors
of red scale populations when insect
growth regulators are used because the
males are more sensitive to these insecticides than the females, and so the
cards underestimate the scale population.
In spite of these limitations, pheromone cards are very useful as one of
several tools for monitoring California
red scale.
Fig. 1. This figure shows a typical pattern of male scale flight activity (red line) and
crawler emergence (green line) and the number of degree-days between the first
flight and each generation. There are usually four flights and emergences in the
San Joaquin Valley. Treatments target the first two crawler emergences because
the population is more uniform and the scales have not yet reached the fruit.
Examining fruit
In all orchards, whether Aphytis
wasps are released or trees are sprayed
with insecticides, conduct visual inspections of citrus fruit on the trees once a
month during August, September, and
October.
Photo 10. Double sticky tape wrapped around the green-grey wood branch of a
tree near a female scale will collect the crawlers when they move toward the end
of the branch.
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stars. During the first two generations,
the crawlers emerge at about the same
time, but as the season progresses to
the 3rd and 4th generations, the crawler
emergence overlaps with other stages.
Be sure not to rely on only one
chemical group, as this will eventually
lead to resistance.
Organophosphates and carbamates: Time organophosphate or carbamate insecticide sprays (Lorsban,
Supracide or Sevin) to treat the crawler
stage, after the peak in the 1st or 2nd
male flight. Optimal treatment timing
varies from year to year because of
temperature but usually occurs in early
May (first generation) or late June-early July (second generation).
An even more reliable method of
timing organophosphate or carbamate
treatments is to monitor for crawlers
by wrapping sticky tape around 1-yearold branches (about 0.5 inch diameter)
that have both gray and green wood
and are infested with live female scales.
Replace the tapes weekly and so determine precisely when crawler emergence is occurring.
The organophosphate and carba-
Predicted fruit infestation levels based on California red scale trap Predicted fruit infestation levels based on California red scale trap 1
catches in traps baited with pheromone in the San Joaquin Valley
catches in traps baited with pheromone in the San Joaquin Valley1
Males/Trap
First Flight
(Apr/May)
Males/Trap
Fourth Flight
(Sep/Oct)
0
1,783
2
0.7
0
1,385
6,263
4
1.3
21
3,006
10,893
6
2.0
43
4,679
15,665
8
2.6
65
6,403
20,594
10
3.3
87
8,184
25,697
12
3.9
111
10,028
30,993
14
4.6
1From
% Fruit with
one or more
scales
% Fruit with 11 or more scales
Males/Trap
Second Flight
(Jun/Jul)
the Integrated Pest Management for Citrus, UC DANR Publication 3303.
Fig. 2. The expected infestation of fruit at the end of the season based on pheromone trap counts in untreated orchards during the 1st, 2nd and 4th male flights.
mate insecticides are the least selective
insecticide choices, causing mortality
of Aphytis for weeks to many months.
There are numerous populations of
California red scale that are resistant
to organophosphate and carbamate
insecticides because of decades of use,
and in these cases treatment will only
partially reduce the scale population.
Insect growth regulators: Apply
Esteem or Applaud sprays after crawlers have completely emerged and become white caps because these insect
growth regulators kill the scale when it
tries to molt to the next stage.
Optimal timing for insect growth
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regulators is the second generation of
scale (June-July) in order to protect
vedalia beetle during the time it is controlling cottony cushion scale (February-May). The insect growth regulators
are safe for parasitic wasps, predatory
mites, spiders, and lacewings but are
quite toxic to vedalia beetles which are
needed for cottony cushion scale control. Often they are used to reduce the
pest population before Aphytis releases are initiated.
Lipid synthesis inhibitors: Make a
foliar application of Movento one to
two weeks after the 1st, 2nd or 3rd male
flights. The systemic action of Movento
takes several weeks to move throughout the tree, so it needs to be applied
A
The heavier oils (435 to 455 distillation
point) exert greater scale control than
light oils (415 oil); however, they also
have a greater potential for phytotoxicity.
When using oils for scale control,
make sure the orchard is well-irrigated
and avoid treating during the heat of
the day. In addition, treatments after
October 1 carry some risk of increasing frost damage. Highly refined oils
with the lowest sulfonated residues
(unsulfonated residues >98%) have
fewer problems with phytotoxicity. See
UCIPM precautions for using petroleum oil sprays: http://www.ipm.ucdavis.edu/PMG/r107301011.html.
Oil has the advantage of being less
damaging to natural enemy populations than other insecticides because
it only kills natural enemies that it
contacts (brief persistence). It is best
to avoid oil use in Aphytis release programs because oil treatments will eliminate the younger scale instars and thus
synchronize development of the scale
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B
Photos 11A and B. In August, fruit can
be infested with scale in Aphytis release
blocks and the scales appear healthy
(A). However, in as little as one month
later, the scales can begin to flake
off of the fruit (B) because they have
been parasitized, leaving behind white
footprints that are easily washed off.
earlier than the other insecticides. On
the other hand, it is effective against all
feeding scale stages (everything except
late stage females and males), so precision of treatment timing is not as important as application technique.
Make sure your orchard is well-irrigated, use 250-500 gpa water volume,
and use an adjuvant such as oil. Movento is very safe for parasitic wasps and
vedalia beetles, but it is toxic to predatory mites.
Oils: Oils can be effective against
California red scale if coverage is thorough and rates of 1.2-1.4% oil are used.
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population. This makes parasitism by
Aphytis more difficult because they
prefer to deposit their eggs in 3rd instar
scale; after an oil treatment, this stage
may be absent for a period of time.
Oil is an organically accepted treatment for California red scale.
Parasite releases
Releases of mass-reared Aphytis
parasites can be useful in orchards with
insufficient natural biological control.
Keep in mind that pesticide residues
on leaves may have a detrimental effect on released Aphytis parasites. Test
for possible toxicity by putting 1-yearold twigs with leaves in gallon jars with
Aphytis parasites for 24 hours and
checking their mortality. If more than
35% have died, residues are too high
for Aphytis releases. Also, prepare a
control jar filled with known untreated
leaves for comparison of Aphytis vigor.
In the San Joaquin Valley, recommended release rates are 100,000 parasites per acre per year for orchards undergoing the transition to an integrated
pest management program. Begin releases about March 1, making releases
of 5,000 parasites per acre every two
weeks with the objective of releasing
50% of the parasites during the critical
spring period, 25% more in summer,
and 25% more in fall. Continue releases through mid-November.
A suggested release method is to
hold the release cup upright and tap it
to release a few Aphytis at every sixth
tree in every sixth row, and start at
different trees each time releases are
made. This helps to spread the weakflying Aphytis through the block. Concentrate late season releases in areas
in the block known to have higher red
scale densities. Once an orchard has
moved through the transition period (2
to 4 years), the total number of parasites released per acre may be reduced
to 50,000 to 70,000.
Control ants – particularly the Argentine ant in Southern California and
the native gray ant in the San Joaquin
Valley – because they disrupt red scale
parasites. Excessive dust that coats the
leaves and fruit, including dust from
manure mulches as well as whitewash
and kaolin clays, interferes with parasitism and should be minimized or delayed until the end of the season when
Aphytis has completed its work. Water-
ing roads and washing trees can help
solve these problems.
Detailed evaluations of parasitism in
Aphytis-release blocks
In orchards where biological control agents such as Aphytis and Comperiella wasps are used to control scale,
visually monitor all stages of scales on
twigs, fruit, and leaves in August, September, and October.
• Collect 10 scale-infested fruit
(preferably from different areas of the
block). Do not take more than one to
two fruit per tree, avoiding trees in the
outside rows.
• Record the number of 2nd and
3rd instar red scales and the number of
these that are parasitized. To determine
if a scale is parasitized, flip the cover
over and search for Aphytis eggs, larvae, and pupae or Comperiella larvae
and pupae (see publication “Life Stages
of California Red Scale and its Parasitoids” http://anrcatalog.ucdavis.edu/
InsectMiteMolluscPests/21529.aspx for
detailed photos).
• Calculate the percentage parasitism by dividing the number parasitized
by the total number of 2nd and 3rd in-
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star scales examined. If biological control is functioning properly, you should
see percent parasitism increase from
just a few percent in August to more
than 70% in October. You should also
see dead parasitized scales flaking off of
the fruit and leaving behind white “footprints” as the season progresses (Photos
11A and B).
Guidelines for determining when
parasitism is at sufficient levels to fully
control scale vary by growing region,
cultivar, and whether or not fruit are
sent to a packinghouse that employs a
high pressure washer to remove scale.
In the San Joaquin Valley, effective
biological control of California red scale
is achieved if by mid-to-late October
more than 70% of the 3rd instar female
scale are parasitized either by Aphytis or
Comperiella. A good proportion (50%)
of large 2nd instar females and 2nd instar males should also be parasitized.
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Summary
California red scale can be effectively managed with Aphytis wasp releases
or insecticide treatments or a combination of the two if you are careful about
insecticide choice, rate, frequency of application, and treatment timing. Careful
monitoring of California red scale populations using pheromone traps, crawler
tapes and fruit inspection can greatly
improve your decision making and provide more sustainable control of scales.
Dr. Beth Grafton-Cardwell is a
University of California Extension
Specialist and Research Entomologist.
She is a Citrus IPM Specialist in the
Department of Entomology at UC Riverside and also serves as Director of the
Lindcove Research and Extension Center. Jim Stewart is a partner in Ag IPM
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Management of citrus thrips to
reduce the evolution of resistance
Joseph Morse and Beth Grafton-Cardwell
Editor’s Note: Work on citrus thrips
is now a part of the CRB’s Core Program of Integrated Pest Management
research with Drs. Grafton-Cardwell
and Morse as lead investigators.
Background
The citrus thrips, Scirtothrips citri
(Moulton), is one of the few pests of
California citrus which is native to California. In this case, the exotic organism
is the citrus tree, and the native is citrus
thrips.
Dudley Moulton, a USDA scientist,
named this insect in 1909 (calling it the
orange thrips) after damage to citrus
in southern Kern County made it clear
that the characteristic surface scarring
of citrus fruit that had been seen for
many years was not wind rubbing or cold
injury as had previously been thought.
Even to the present day, it can be a
challenge to differentiate citrus thrips
damage from wind-caused fruit scarring.
We like to use the presence of a partial
or complete ring scar around the button
as one good criterion – this is normally
present with citrus thrips damage. In addition, checking fruit for damage shortly
after petal fall will reveal the early stages
of citrus thrips-induced fruit scarring.
The article listed in “Further Reading”, Grafton-Cardwell et al. 2003, contains pictures that aid in differentiating
citrus thrips fruit scarring from other
types of fruit injury.
tree, looking for a place to hide, where
they pass through two relatively inactive
and non-feeding stages, the propupa
and pupal stages. Typically, about onethird of the thrips pupate in cracks and
crevices in the tree. and two-thirds drop
to the soil to pupate in the upper layers
of the leaf duff and soil beneath a tree.
Fig. 1. It is the first and second instar
(larger, above) citrus thrips that cause
most fruit scarring. Photo by Jack Kelly
Clark, courtesy UC Statewide IPM Program.
Natural enemies of citrus thrips
The life cycle of citrus thrips
Citrus thrips starts its life as an egg
laid inside young leaves, twigs, flowers,
or fruit. The most damaging stages are
the first and second instar larvae (Figure
1), because they prefer to hide under the
button when the fruit is small, concentrating their feeding in that area, which
causes the characteristic ring scar as the
fruit expands.
Mature second instar larvae crawl
towards the inside, dark portions of the
The adults then emerge, mate, and
produce the next generation of thrips.
Adult females concentrate their feeding in one area to a lesser extent than
larvae, and males don’t feed all that
much or live very long -- thus they are
not considered as damaging as the larvae
in most situations.
There are eight or more generations
of citrus thrips attacking the leaves and
fruit of citrus over the spring, summer,
and fall. The first generation in the
spring feeds on the leaf flush prior to
bloom, and the second generation of
larvae typically appears about the time
of petal fall. It is the second and third
generation of citrus thrips that normally
are of economic concern.
Small fruit are fairly susceptible to
citrus thrips scarring, and as the fruit
grows it becomes less susceptible. Once
fruit are larger than about 1.5 inches in
diameter, citrus thrips do not typically
cause economic scarring because the
fruit is tough enough to make extensive
feeding difficult (thrips feed best on
tender leaf and fruit tissue).
Coastal lemons are an exception to
the above scenario because multiple
fruit sets are produced over the year.
Rather than being a spring pest, citrus
thrips on coastal lemons typically isn’t
a concern until the mid-to-late summer
fruit set.
Fig. 2. The predaceous mite Euseius
tularensis will feed to some degree
on citrus thrips (here feeding on a late
second instar thrips). Photo by Jack
Kelly Clark, courtesy UC Statewide IPM
Program.
We have searched for many years for
ways in which to manage citrus thrips
non-chemically and, in particular, with
natural enemies. A number of natural
enemies will feed on citrus thrips, but,
unfortunately, in years when thrips levels are high they can cause substantial
fruit injury in a relatively short period
of time. Natural enemies often cannot
keep up with the rapid growth of spring
thrips populations.
The only stages readily available
for natural enemy attack are the first
and second instar larvae. The two pupal
Thrips
Leafminer
Katydids
Peelminer
Asian citrus psyllid
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stages are typically hidden in cracks
or crevices in the tree or the soil, the
winged adults are difficult for most
predators to capture, and the egg stage is
fairly protected inside plant tissue. Thus,
any predator species trying to “make
a living” off citrus thrips has sporadic
availability of the larvae and cannot
respond well numerically to increased
thrips levels within a particular year.
Triapitsyn & Morse (1999) searched
for wasp parasitoids attacking citrus
thrips and, although they found low
levels of two parasitoid species on laurel sumac (a common native host, see
below), these insects were not found
associated with citrus. The citrus thrips
has adapted over time to citrus, but
perhaps the parasitoids have not, or they
are not present at high enough levels to
be detected easily.
Jones & Morse (1995) used isoelectric gel electrophoresis to study
to what degree the predaceous mite
Euseius tularensis (Figure 2) feeds on
citrus thrips, as this predator has been
proposed as one of the more common
natural enemies of citrus thrips on California citrus. Only 7 of 556 (1.3%) adult
female E. tularensis tested positive for
citrus thrips in their gut. Given this, we
wonder if E. tularensis perhaps reduces
citrus thrips levels only when the pest
first starts to build from low levels but
not when both species are present at
moderate to high levels.
Euseius spp. are generalist predators that feed on pollen, mites, insects
and leaf sap, so they are not specifically
tracking citrus thrips populations. Grafton-Cardwell demonstrated that pruning and fertilizing trees generated higher
densities of Euseius than augmentative
releases by providing the environment
Euseius prefers. It is generally accepted
that densities of >0.5 Euseius per leaf are
associated with good citrus thrips control, but it is possible that the presence of
this level of Euseius is indicative of good
biological control in general because a
suite of natural enemies provide citrus
thrips suppression rather than Euseius
specifically.
Monitoring for citrus thrips
Strategies used by pest control advisors and growers for managing citrus
thrips vary. PCAs typically monitor
citrus thrips levels on young, developing
fruit immediately after petal fall to decide if treatments are needed. Post-petal
fall treatments are not needed every
year. This is because thrips levels vary
from year to year, and also the timing of
when the second and third generation of
immature thrips appears in relation to
fruit size varies. In the San Joaquin Valley, wet weather during bloom typically
results in lower thrips levels after petal
fall, in part due to greater mortality of
the pupae in the soil.
Careful monitoring can reveal orchards that have low levels of immature
thrips on young fruit, and treatments
can be delayed or eliminated altogether.
Reducing the number of treatments will
reduce the selection pressure for resistance to insecticides. Problems controlling citrus thrips in a particular grove are
more likely if one or more treatments
are used each year in contrast to a treatment perhaps being used only 5 years
out of 10 years based on sampling for
thrips severity each year. Insecticides can aggravate thrips
populations
Fig. 3. We rate navel orange scarring
caused by citrus thrips on a 0-4
scale where 0 = no scarring by citrus
thrips (not shown), 1 and 2 are slight
scarring (not sufficient to cause
fruit to be downgraded from first to
second grade) and 3 and 4 are severe
(economic scarring). The threshold for
fruit downgrading varies from year to
year but is typically set at a level of 3
scar or worse.
Over the period 1972 – 2003, we ran
citrus pesticide screening trials in Field
12 (Atwood navel oranges) at the Lindcove Research and Extension Center
(LREC). Untreated control plots were
always included in order to assess how
much fruit scarring would result if no
treatment were applied.
We used a 0-4 rating scale to assess
the severity of citrus thrips-caused fruit
scarring (see Figure 3), and scarring
levels 3 and 4 were categorized as “economic scarring”. We set the threshold
for economic scarring as the level that
would typically lead to fruit being downgraded from first to second grade.
Over the 20 years 1972-1991 (data
prior to 1981 from O. L. Brawner and
Dr. Bill Ewart), citrus thrips economic
scarring on untreated trees ranged from
1.2% (1986) to a maximum of 69.0%
(1988) on outside lower fruit with a
mean of 30.2% economic scarring. In
contrast, over the 12 years 1992-2003,
economic scarring ranged from 0.1%
(2000) to a maximum of 10.7% (1997)
with a mean of 4.4%.
Clearly, something changed dramatically between these two time periods.
The maximum level of severe scarring
over the latter time period was about
1/3 of the average level over the earlier
period. We believe the reason for this
is that citrus thrips is, to a considerable
degree, a pesticide-induced pest.
During the first time period, 19721991, broad-spectrum organophosphate,
carbamate, and pyrethroid insecticides
were used in the SJV and in the test
areas of this field at Lindcove for citrus
thrips control. Many pest control advisors mentioned to us that spraying thrips
“only makes them mad”. They found
that if the first spray did not control
them well, they “came back” at very high
levels and were more difficult to control.
We believe that what was happening was that citrus thrips populations
had developed resistance in some areas
and to varying degrees to organophosphates, carbamates, and/or pyrethroids.
The level of resistance varied greatly
depending on how often and which
chemicals had been used in the past and
how long thrips had NOT been exposed
to that chemistry so that resistance
could revert.
When citrus thrips are sprayed with
a broad-spectrum insecticide (as is the
case for most products in these three
classes of chemistry, see Table 1) these
sprays reduce most natural enemies that
might help hold the thrips in check. If
the thrips are somewhat resistant, they
are not completely killed.
Hormoligosis is the term used to
describe the stimulation of insects or
mites when they are exposed to sublethal rates of pesticides or other toxins.
As pesticide residues drop to sub-lethal
rates, citrus thrips can be stimulated
(depending on pesticide and dose) to
lay more eggs, contributing to a “resurgence” of the thrips population several
weeks later.
Hormoligosis — the stimulation of insects or mites when they are exposed
to sub-lethal rates of pesticides or
other toxins.
What happened to contribute to
lower thrips levels over 1992-2003? The
relatively “soft” insecticides Agri-Mek
and Success (Entrust is the organic version) were registered for use on California citrus in 1994 and 1998, respectively,
and growers largely switched to using
those products, especially Success, for
citrus thrips control (see Figure 4). In
addition, growers switched to Esteem
or Applaud for red scale control, in both
cases replacing broad-spectrum organophosphate, carbamate, and pyrethroid
treatments with softer insecticides
that allowed more natural enemies to
survive.
Thus, although citrus thrips can still
cause economic damage when weather
conditions are conducive, in general,
citrus thrips is less of a problem than it
used to be. Whereas citrus thrips insecticide screening trials at LREC were
quite productive prior to 2003, once the
“organophosphate era” ended, it was
difficult to consistently see differences
between fruit scarring on trees treated
with the standard, effective product
versus levels on untreated control trees.
We shifted in 2004 to screening
experimental pesticides on what we
believe is one of the major natural hosts
of citrus thrips in California (before
citrus was introduced), laurel sumac,
in greenhouse trials (see Morse 1995).
Treatments on non-bearing citrus
Some growers and PCAs believe
that treating citrus thrips on non-bear-
Table 1. Pesticides that might be used in rotation for citrus thrips control.
Trade name
Common name
Pesticide class
Mode of Actiona Critical as part Resistance situation with of future ACP citrus thrips
control?
Comments and application
methods to improve efficacy Dimethoate (and DimethoateOrganophosphate 1B
Yes
generics)
Resistance in some areas
depending on the degree of
past organophosphate use
Moderately systemic material
Carzol
Formetanate Carbamate 1A
No?
hydrochloride
past carbamate use Veratran D
Sabadilla alkaloidsBotanical unclassified
No
Resistance not yet seen with citrus thrips (seen with avocado thrips)
Baythroid XLBeta-cyfluthrin
Pyrethroid
3A
Yes
Danitol Fenpropathrin Mustang
Zeta-cypermethrin
Adding 1-2 gallons of
molasses/acre assists with
efficacy and persistence;
Critical to reduce spray tank
pH to 4.5 prior to adding
material; Works poorly in
cold weather (active only as
a stomach poison)
past pyrethroid use
Agri-Mek (and Abamectin
Chloride channel 6 Somewhat
Possible cross-resistance
generics)
activator
(adults)
with class 5
Translaminar, add oil (1/4%
or more) to aid leaf
penetration and persistence
Success
Entrust
Delegate
Translaminar, add oil (1/4%
or more) to aid leaf
penetration and persistence
Spinosad
Spinosyn
5
Delegate –
Possible cross-resistance
Spinosad (organic)
Yes
with class 6
Spinetoram
Movento
Spirotetramat
Inhibitor of acetyl 23
Yes
CoA carboxylase a
The IRAC MoA (mode of action) for each class of chemistry (see www.irac-online.org).
Resistance management
critical to protect this material’s efficacy for ACP, red scale, and citrus thrips control
Highly systemic; add oil to
improve leaf penetration
(surface residues are NOT
active)
treatments over years 1-3. In this study,
we also measured fruit production in
year 3. Although we saw a slight numerical trend with somewhat more fruit in
the treated plots, this difference was not
statistically significant. By year 4, this
slight numerical trend had disappeared
(an average of 244.5 fruit per tree on
treated trees, 249.0 on untreated trees).
Our conclusion for both the navel
and Valencia studies is that despite leaf
scarring caused by citrus thrips being
unsightly, treating young citrus very
much, if at all, is likely wasting money
and can significantly contribute to the
evolution of pesticide resistance.
We strongly suggest that growers
not treat citrus thrips on non-bearing
citrus except perhaps the first year when
trees are very small. The cost, in terms
of losing the efficacy of pesticides to
resistance, is too high and this is going
to be even more important once treatments are needed for Asian citrus psyllid
(ACP) control.
The history of citrus thrips pesticide
resistance
Table 2 shows that over the years,
citrus thrips has evolved pesticide resis-
Fig. 4. Damage of young flush on citrus can be unsightly but does not warrant
treatment except perhaps on very young trees just after planting. Photo by Jack
Kelly Clark, courtesy UC Statewide IPM Program.
Cygon
Carzol
Baythroid
Baythroid XL
Agri-Mek
Veratran
Success
Delegate
2009
2007
2005
2003
2001
1999
1997
1995
1993
450,000
400,000
350,000
300,000
250,000
200,000
150,000
100,000
50,000
0
1991
Insecticides Used for Citrus Thrips & Katydid Control
in the San Joaquin Valley
Acres Treated
ing, young citrus has value in terms of
enhancing tree growth and/or bringing
the tree into production sooner. We
suggest it is perhaps worthwhile treating
for citrus thrips only in year 1, when the
trees are first planted in the ground to
ensure they get a good start.
For older trees, we admit that the
leaf scarring of young leaves by citrus
thrips is unsightly (Figure 5), but does
citrus thrips really slow the growth of
young trees, if they are well irrigated,
well watered, and otherwise healthy?
We believe the answer to that is no,
based on two research trials reported
in Grafton-Cardwell et al. (1997) in the
San Joaquin Valley.
The first study was done on navel
oranges at LREC using 50 single-tree
replicates over a three-year period.
Treatment 1 never received any pesticides, and treatments 2-6 received 2
summer treatments in year 1. In years
2 and 3, the treatments were: (2) no
citrus thrips treatments; (3) 2-3 spring
treatments/year; (4) 1 fall treatment/
year; (5) 2-3 spring and 1 fall treatment
each year; and (6) 2-3 spring, 4 summer,
and 1 fall treatment each year. Thus,
trees received as many as 17 treatments
over a three-year period. As an indication of tree growth, we measured trunk
circumference at 4 cm above the bud
union 1, 2, 3, and 4 years after the trees
were planted.
To summarize the results, none of the
6 treatments had a differential impact on
tree growth; that is, we could detect no
difference in tree size during years 1-3
whether they were untreated, treated
with 17 treatments, or with an intermediate number of treatments. The only
significant effect we measured was a loss
in citrus thrips susceptibility to Carzol.
The second study was done with
commercial Valencia oranges planted
in April in Fresno County over a threeyear period. A 20-acre block was divided
into 18 plots of 180-200 trees each, and
9 plots were randomly assigned to be
treated with (1) no citrus thrips treatment over years 1-3 or (2) grower choice
of treatments including a range of insecticides used for citrus thrips control
(7 treatments in year 1, 7 in year 2, 5
in year 3). The entire field was treated
after petal fall in the spring of year 4 to
protect fruit from citrus thrips scarring.
Again, we measured trunk diameter
in years 1-4 and saw no difference between 0 treatments and, in this case, 19
Danitol
Fig. 5. Insecticide acreage treated with various insecticides for citrus thrips
and katydid control demonstrating the changes in grower uses during 19912010 for the San Joaquin Valley. Totals for Cygon and Agri-Mek include generic
formulations of the same chemical.
tance to a number of different pesticides
from DDT to pyrethroids in as short a
time as 1 year (to Dieldrin after resistance to the related DDT had appeared)
and in as many as 18 years (dimethoate).
We now have evidence for resistance to
Delegate in a population of citrus thrips
in the San Joaquin Valley.
Citrus thrips’ ability to rapidly develop resistance concerns us each time
growers consistently rely on one or a
small number of insecticides for the control of a particular pest (citrus thrips, red
scale, ACP, etc.). Unfortunately, we often
do not have as many effective pesticides
from different classes of chemistry available for rotation as is desirable.
What is meant by the word “resistance”? There are a number of
definitions, but we like two of the more
common ones: (1) if the “resistant”
population of insect or mite develops
a >10-fold increase in the LC50 or LC90
(the pesticide concentrations needed to
kill 50 or 90% of the population, respectively) or (2) if one sees clear evidence
of a lack of field control (either complete
failure or reduced persistence) when the
material is used properly.
The first definition recognizes that
there is variability in the response of
various insects and mites to pesticides,
and a population has not developed
resistance until at least a 10-fold level
has been reached. The latter definition
is more of an operational term – when
the material stops working or works
less well, resistance has occurred. In
most cases, laboratory measurements
and field experience correlate well.
Researchers typically try to take
baseline resistance data in the labora-
tory before a pesticide is used widely
so they can later watch for changes
in responses to the insecticide and
confirm those changes based on field
observations.
Sometimes resistance to one insecticide also confers resistance to
another insecticide. This is known as
“cross resistance”. One way that insects
resist pesticides is by breaking down
(metabolizing) the pesticide more
quickly; this is called metabolic resistance. Citrus thrips that have evolved
resistance to organophosphates have
increased levels of enzymes that break
down the organophosphate relatively
quickly compared to susceptible strains,
and this also gives them resistance to
other organophosphate and carbamate
insecticides (MoA category 1, Table 1).
A second type of resistance is due to
an altered target site for the pesticide.
The rapid development of citrus thrips
resistance to pyrethroids may be due
to previous exposure to DDT because
these two types of pesticides have similar target sites (MoA 3).
Following the registration of Success
(spinosad) for use on California citrus in
1998, Success and Entrust were widely
used for citrus thrips control, accounting for an average of 43% of the spring
thrips/katydid treatments in the San
Joaquin Valley between 1999 and 2007
(Figure 4).
Delegate (spinetoram) was registered in 2007, is in the same class of
chemistry as Success (cross resistance
is expected), and is somewhat more
effective and persistent against citrus
thrips than Success. The use of Delegate
until recently was hampered by the lack
of MRLs (maximum residue limits) by
some of the foreign trading partners to
which California citrus is shipped. Each
year over the last six years or so, we have
offered to test for citrus thrips susceptibility to either Success or Delegate
based on baseline data we took before
these products were widely used.
Each year, we have been pleasantly
surprised to see a lack of documentable
resistance. However, following a report
of poor citrus thrips control from a
Delegate application during the spring
of 2011, we measured a significant increase in the spinetoram LC50 for citrus
thrips collected at this location (9.4
to 19.8-fold higher LC50 than baseline
values determined in 2008). Actually,
we should feel very fortunate that it has
been 14 years before the first signs of
field resistance were observed with the
Success/Delegate chemistry in the San
Joaquin Valley.
The need to manage citrus thrips
resistance
We plan to continue to monitor the
Delegate resistance situation to determine whether this is a fairly isolated
incident and whether such resistance is
developing in other areas of the SJV. In
addition, we are accelerating the testing
of new products and chemistries which
might be used to help manage citrus
thrips resistance (several are moving
closer to registration).
As mentioned by Morse & GraftonCardwell (2009), once Asian citrus
psyllid enters the SJV, it will be even
more important to manage pesticide
resistance by rotating between products
with different modes of action, as many
Table 2. Partial history of citrus thrips pesticide resistance evolution in California.
Pesticide common Class of chemistry
Mode of Actiona
name
DDT
Sodium channel modulator
Sabadilla + sugarBotanical bait
Dieldrin
GABA-gated chloride channel antagonist MalathionOrganophosphate DimethoateOrganophosphate Carzol
Carbamate Baythroid
Pyrethroid
Abamectin
Macrocyclic lactone
Success + oil
Spinosyn
Delegate + oil
Spinosyn
Movento + oil
Acetyl CoA carboxylase inhibitor
a
b
3
unclassified
2A
1A
1A
1B
3
6
5
5
23
Year first used
commercially
1946
1948
1953
1954
1962b
early 1980s
1991
1994
1998
2007
2008
Year first field
failure reported
1949
--
1954
1961
1980
1986
1996
--
--
2011
--
Reference
Morse & Brawner 1986
Immaraju et al. 1989
Morse & Grafton-Cardwell 2009
--Morse et al. unpublished
The IRAC MoA (mode of action) for each class of chemistry is listed (see www.irac-online.org). Cross-resistance is expected between chemicals with the same mode of action.
Non-bearing (limited) use only, until 1969.
of the materials that are effective against
citrus thrips also will assist in control of
ACP (see Table 1). There are currently
six modes of action (1, 3, 5, 6, 23, and
unclassified) for insecticides registered
for citrus thrips control (Table 1).
The best advice regarding resistance
management for citrus thrips, or most
pests for that matter, is to: (1) minimize
pesticide use to the extent that is possible by sampling carefully to make sure
the treatment is needed; (2) maximize
the use of non-chemical control methods; (3) rotate among effective available
chemistries to the maximum extent
possible (clearly understand what mode
of action each pesticide has and where
the potential for cross resistance exists);
and, (4) when a treatment is needed,
apply it at the optimal time and with
the best possible application method
so as to avoid the need for re-treatment
(Table 1).
We view the first observation of
citrus thrips resistance to Delegate in
2011 as an early warning. To maintain
the effectiveness of Delegate and Success against citrus thrips, avoid making
more than one application of a Group
5 insecticide (Delegate, Success, or
Entrust) to a block each year. If additional applications are needed, other
effective insecticides with different
modes of action should be used. Also,
try to make applications to adjacent
blocks or groves at the same time or
within a few days of each other to have
an “area-wide” impact and thus slow
re-infestation.
It is important that we hold this
situation in check as best we can until
new chemistries become available for
citrus thrips control. It is hoped we will
have at least one new chemistry to use
against citrus thrips prior to the 2013
spring field season.
Acknowledgements
We would like to thank the Citrus
Research Board for funding to support
in part the research described herein. We
also thank Alan Urena, Lindsay Robinson, Pamela Watkins, and Heavenly
Clegg for technical support and past
graduate students/postdoctoral scientists Tim Grout, Bill Wiesenborn, Alex
Rhodes, John Immaraju, Nasser Zareh,
Jim Ferrari, Steven Jones, Heinrich Sch-
weizer, Inamullah Khan, Kris Tollerup,
and Dr. Serguei Triapitsyn for contributing to past citrus thrips research efforts
which lead to some of the information in
this article. Photographs 1, 2, and 4 were
provided by Jack Kelly Clark, courtesy
of the UC Statewide IPM Program and
are copyrighted by the Regents of the
University of California.
Dr. Joseph G. Morse is a Professor
of Entomology and Dr. Beth GraftonCardwell is an Extension Specialist and
Research Entomologist. Both are members of the Department of Entomology,
University of California Riverside.
Further reading
Grafton-Cardwell, E.E., J.G. Morse,
and A. Gjerde. 1997. Effect of Insecticide
Treatments to Reduce Infestation by
Citrus Thrips (Thysanoptera: Thripidae) on Growth of Nonbearing Citrus.
Journal of Economic Entomology 91(1):
235-242.
Grafton-Cardwell, E.E., N.V.
O’Connell, C.E. Kallsen, and J.G. Morse.
2003. Photographic Guide to Citrus
Fruit Scarring. University of California
Division of Agriculture and Natural
800-992-2304
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SOURCE
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Resources Publication 8090, Oakland,
CA. 8 pp.
Haviland, D.R., S.M. Rill, and J.G.
Morse. 2009. Southern Highbush Blueberries Are a New Host for Scirtothrips citri (Thysanoptera: Thripidae) in
California. Florida Entomologist 92(1):
147-149.
Jones, S.A. and J.G. Morse. 1995. Use
of Isoelectric Focusing Electrophoresis
to Evaluate Citrus Thrips (Thysanoptera: Thripidae) Predation by Euseius tularensis (Acari: Phytoseiidae). Environ-
mental Entomology 24(5): 1040-1051.
Immaraju, J.A., J.G. Morse, and D.J.
Kersten. 1989. Citrus Thrips (Thysanoptera: Thripidae) Pesticide Resistance in
the Coachella and San Joaquin Valleys
of California. Journal of Economic Entomology 82(2): 374-380.
Immaraju, J.A., J.G. Morse, and R.F.
Hobza. 1989. Field Evaluation of Insecticide Rotation and Mixtures as Strategies for Citrus Thrips (Thysanoptera:
Thripidae) Resistance Management in
California. Journal of Economic Ento-
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trademarks of Nichino America, Inc. Farm Safely. Always read and follow label
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mology 83(2): 306-314.
Lovatt, C.J., S.M. Streeter, T.C.
Minter, N.V. O’Connell, D.L. Flaherty,
M.W. Freeman, and P.B. Goodell. 1984.
Phenology of Flowering in Citrus sinensis (L.) Osbectk, cv. Washington navel
orange. Proceedings of the International
Society of Citriculture 1: 186-190.
McMurtry, J.A. and B.A. Croft. 1997.
Life-styles of Phytoseiid Mites and Their
Roles in Biological Control. Annual Review of Entomology 42: 291-321.
Morse, J.G. 1995. Prospects for IPM
of Citrus Thrips in California. Pp. 371379, In: Thrips Biology and Management. Proceedings, 1993 International
Conference on Thysanoptera, Towards
Understanding Thrips Management.
Editors: B.L. Parker, M. Skinner, T.
Lewis. Sept. 28-30, 1993, Burlington, VT.
Plenum, New York, NY. 636 pp.
Morse, J.G. and O.L. Brawner. 1986.
Toxicity of Pesticides to Scirtothrips citri
(Thysanoptera: Thripidae) and Implications to Resistance Management. Journal
of Economic Entomology 79(3): 565-570.
Morse, J.G. and H. Schweizer. 1996.
Citrus Thrips Resistance — A Problem
Requiring Grower and PCA Restraint.
Citrograph 81: 11-15.
Morse, J.G. and E.E. GraftonCardwell. 2006. Bear Citrus Thrips
Resistance in Mind When Deciding
Whether and How to Treat in 2006. Topics in Subtropics 4: 11-13.
Morse, J.G. and N. Zareh. 1991.
Pesticide-Induced Hormoligosis of Citrus Thrips (Thysanoptera: Thripidae)
Fecundity. Journal of Economic Entomology 84(4): 1169-1174.
Morse, J.G. and E.E. GraftonCardwell. 2009. Managing Insecticide
Resistance will be Key to the Future
of Effective Citrus Pest Management.
Topics in Subtropics 7(1): 6-8.
Morse, J.G., E.E. Grafton-Cardwell,
and A.A. Urena. 2001. Management Options for Citrus Thrips in the San Joaquin
Valley. Citrograph 86: 4-5, 12.
Rhodes, A.A., J.G. Morse, and C.A.
Robertson. 1989. A Simple Multigeneration Phenology Model: Application to
Scirtothrips citri (Thysanoptera: Thripidae) Prediction on California Oranges.
Agriculture, Ecosystems and Environment 25(4): 299-313.
Triapitsyn, S.V. and J.G. Morse. 1999.
Survey of Parasitoids of Citrus Thrips,
Scirtothrips citri (Moulton, 1909), in
Southern California. Russian Entomology Journal 8(1): 47-50.l
The evolution of biologically-based
Integrated Pest Management in California citrus:
history and perspective
Joseph Morse and Beth Grafton-Cardwell
C
itrus production in California occurs in four major
climatic growing regions. These include coastalintermediate Southern California, interior Southern
California, the Southern California desert valleys, and the San
Joaquin Valley (Figure 1).
Historically, the Southern California growing regions
dominated in acreage, but over the past 50 years or so urban
pressures, including rising land values and water costs, have led
to a shift in acreage. Currently, more than 75% of the state’s
citrus acreage is located in the San Joaquin Valley.
Each of the climatic regions has somewhat different
weather, key pest problems, levels of endemic biological
control, and levels of adoption of biologically-based citrus
IPM practices.
The fumigation era
The history of citrus arthropod pest management in California may be divided into three major eras, each of them
broadly overlapping in time and showing regional differences.
The first of these, prior to the introduction of DDT insecticide in 1946, might be called the “fumigation era.” During
this period, beginning with the introduction of hydro-cyanic
acid (HCN) in 1886 in California, all non-fumigant pesticides
available (Paris Green, lead and calcium arsenate, oil, sulfur,
lime sulfur, nicotine, rotenone, pyrethrum, etc.) had limited
efficacy by modern standards. At peak use of HCN on citrus in
California (1930-1940), as much as 6 million pounds of liquid
HCN was used in a single season.
This era was also characterized by numerous examples of
rather high quality observational research focused on various
aspects of taxonomy, basic biology, and the ecology of citrus
pests. In addition, classical biological control (returning to
the area of origin to search for and import natural enemies
that co-evolved with the target pest) solved a number of pest
outbreaks caused by the introduction of exotic citrus pests
into California from various regions of the world.
The science and philosophy of classical biological control
originated with the outstanding control of cottony cushion
Photo 1. Vedalia beetle adult,
eggs, and larva feeding on
cottony cushion scale.
Photo by Jack Kelly
Clark, courtesy UC
Statewide IPM
Program.
San Joaquin Valley Navels,
Valencias & Mandarins
Coastal
Lemons
Fig. 1. Major growing regions for
citrus in California.
Southern Interior
Navels & Valencias
Desert
Grapefruit
Photo 2. California red scale infested orange.
Photo by Beth Grafton-Cardwell.
Photo 3. First and second instar citrus thrips
are the stages that damage fruit. Photo by
Jack Kelly Clark, courtesy UC Statewide IPM
Program.
Photo 4. Aphytis melinus wasps parasitizing
California red scale. Photo by Jack Kelly
Clark, courtesy UC Statewide IPM Program.
scale achieved by introducing the vedalia beetle (Photo 1)
and Cryptochaetum fly into Southern California citrus groves
in 1888. This led, in part, to the establishment of strong research units emphasizing biological control of pests of citrus
and other crops at both Berkeley and Riverside within the
University of California system.
The philosophical bias in favor of chemical control of citrus
pests maintained its momentum in California, however, with
the commercial introduction of parathion in 1949, dieldrin
in 1953, and malathion in 1954. Since that time, a number of
other organophosphate and later, carbamate insecticides, were
introduced and relied upon by growers.
The pesticide era
Biologically-based IPM
The second era in the history of citrus pest management in
California, ranging from perhaps 1946 to the mid 1970s, might
be called the “pesticide era” following the introduction of
DDT and other organochlorines, and later, organophosphate
and carbamate insecticides.
DDT was experimentally tested on citrus against California red scale (Aonidiella aurantii) (Photo 2) in 1943, was
released for commercial use in the U.S. in 1945, and was first
used commercially on California citrus in 1946.
Throughout the U.S., the unprecedented level of control
achieved with DDT on a wide range of pest species initiated,
in retrospect, a shift of entomological research from a focus
on basic pest biology to an emphasis on various aspects of
chemical control. As an index of this shift, the percentage
of research papers published in the Journal of Economic
Entomology on the general biology of insect pests and their
biological control dropped from 33% in 1937 to 17% in 1947,
while the percentage devoted to the testing of insecticides
rose from 59% to 76%.
More so than with other commodities, however, research
on basic pest biology, and especially biological control, continued on citrus in California during the pesticide era, due in
large part to the presence and citrus focus of an independent
Department of Biological Control at the University of California, Riverside and Berkeley campuses (at the time, this
was a single department).
Although we use the date of the introduction of DDT on
citrus in California in 1946 as the start of the pesticide era,
DDT use on citrus in the state had a limited lifespan. One
of its main uses was for control of citrus thrips (Scirtothrips
citri) (Photo 3), but resistance to DDT appeared in this species in 1949 (and is still present), resulting in reduced use in
the following years.
The third era, which we might call the “biologically-based
integrated pest management era” has a less discrete beginning on citrus in California and continues to evolve to the
present day.
Here we define the biologically-based IPM approach
as the combined use of selective chemical, biological, and
cultural controls. The biologically-based approach includes
regular monitoring of pest and natural enemy species, augmentative release of biological control agents such as Aphytis
melinus (Photo 4) for control of California red scale, and use
of economic thresholds which limit pesticide applications to
an “as-needed basis”. The choice of selective pesticides and
the timing and method of their application is made in a way
that minimally interferes with endemic and augmentatively
released natural enemies.
Biologically-based IPM emphasizes the use of biological
control and minimizes the use of pesticides that would
be harmful to natural enemies. This is done by the careful
selection of which pesticides are used and/or when and
how they are applied. It requires the input of a supportive
grower and a knowledgeable pest control advisor who
carefully tracks pest and natural enemy populations. Such
a system must be responsive to the appearance of new pest
species and the year-to-year variability in pest and natural
enemy populations.
Origins of biologically-based citrus IPM in California
A major tenet of biologically-based citrus IPM is a recognition of the importance of maintaining endemic (natural)
biological control through minimal use of broad-spectrum
pesticides, minimization of dust caused by vehicular traffic, and
suppression of ant species which interfere with natural enemies.
In California, the appreciation for biological control was
stimulated, in part, by classical biological control successes on
citrus in Southern California. Following the example of cottony cushion scale, as new citrus pest species were introduced
into the state, foreign exploration programs were initiated with
the aim of introducing effective natural enemies of these pests.
Many of these programs were initially unsuccessful but
eventually led to control of the target or other non-target
pests through the accumulation of a complex of natural enemy
species or the introduction of a key natural enemy species.
In Southern California, 13 exotic pests have been controlled biologically. Successes include the complete control
of citricola scale (Coccus pseudomagnoliarum) in Southern
California, where it is almost never seen presumably due to
natural enemies introduced to control black scale (Saissettia
oleae).
Other classical biological control successes include control
of purple scale (Lepidosaphes beckii), Comstock mealybug
(Pseudococcus comstocki), citrophilus mealybug (P. calceolariae), longtailed mealybug (P. longispinus), citrus mealybug
(Leptomastidae abnormalis), Japanese bayberry whitefly
(Parabemesia myricae), citrus whitefly (Dialeurodes citri), and
cloudy-winged whitefly (D. citrifolii).
Many other arthropod pests of citrus in California are
partially controlled in one or more of the growing regions in
California by introduced or endemic natural enemies.
In addition to classical biological control, the practice of
augmentatively releasing biological control agents has a long
and successful history on California citrus. The Fillmore Citrus
Protective District (FCPD) was established in 1922 in coastal
Southern California, mainly as a grower cooperative to assist
with control of California red scale. In 1926, citrophilus mealybug, first introduced into the state in 1913, became a serious
problem for FCPD growers and led to the construction of
an insectary for rearing and annual release of the mealybug
destroyer (Cryptolaemus montrouzieri).
In 1937, the FCPD insectary began rearing and releasing
Metaphycus helvolus (Photo 5) for black scale control and, in
1960, Aphytis melinus rearing began for control of California
red scale in grower-member groves. Unfortunately, a declining
Valencia orange market and conversion of groves to other
uses resulted in closure of the FCPD and its insectary in 2003.
Augmentative biological control is the practice of rearing and releasing large numbers of a natural enemy species
to “augment” the impact of other natural enemies that are
present. In the San Joaquin Valley, predators and parasitoids
attack California red scale but without augmentation, their
impact is usually insufficient to maintain red scale below
economic levels.
During the pesticide era, growers and pest control advisors in coastal and interior citrus growing regions of Southern
California, often working in cooperation with researchers
from the Citrus Experiment Station (CES) at Riverside, experimented with and implemented reduced pesticide input
pest management programs. Many of these programs were
coupled with the release of newly imported natural enemies
or with insectary-reared natural enemies.
Southern California growers started relying heavily on
biological control after the mid-1960’s once the introduced
Photo 5. Metaphycus helvolus parasitizing a soft scale.
Photo by A. Kapranas.
parasitoid A. melinus started suppressing California red scale
below levels of economic concern. Many growers in coastal
areas started using twice annual (spring and fall) oil sprays to
maintain key pest species such as California red scale, citrus
bud mite (Eriophyes sheldoni), and others below economic
levels, and were thus able to avoid the use of other pesticides.
By the mid-1970’s, several progressive pest control advisors in coastal and interior Southern California had developed
a biologically-based citrus IPM program which emphasized
pest monitoring, selective pesticide use, and augmentative
releases of insectary-reared A. melinus for California red
scale control.
Development of a biologically-based IPM program for
SJV citrus
During the latter period of the pesticide era, citrus production in the San Joaquin Valley (SJV) relied heavily on
broad-spectrum pesticide use. Despite repeated attempts by
pest control advisors and CES scientists to introduce various
facets of biologically-based citrus IPM into the SJV, growers
showed limited interest in reducing broad-spectrum pesticide
use, and in the context of these treatments and the extremes
of summer and winter temperatures, natural enemy effectiveness was limited.
In the mid-1980’s, a group of UC Experiment Station
scientists, Cooperative Extension advisors, and pest control
advisors from both Southern California and the SJV (with
funding provided by the Citrus Research Board, UC Statewide
IPM Program, California Energy Commission, and the USDA
Office of International Cooperation and Development) developed and tested a biologically-based citrus IPM program at
the Crown Butte Ranch in Tulare County using methodologies
and concepts originally developed in Southern California.
After several years of research and evaluation, this IPM
program was disseminated as a model that might be used on
citrus throughout the SJV. The program consisted of specific,
intensive monitoring methods, intervention thresholds, and
selective insecticide recommendations for each of the major
arthropod pests found on SJV citrus at that time.
Key among these were use of sabadilla (Veratran D; at the
time, other selective options were not available), a botanically
derived insecticide mixed with sugar or molasses as an attractant for citrus thrips control, various formulations of Bacillus
thuringiensis (Bt) for ”orangeworm” control, narrow range
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oil for citrus red mite, low rates of chlorpyrifos (Lorsban)
for katydid, citricola scale, and initial red scale knockdown,
and management of California red scale through augmentative releases of 50,000-100,000 insectary-reared A. melinus
parasitoids per acre per year.
The Aphytis were released every two weeks beginning
mid-February and ending mid-November each year, for a total
of 20 releases of 2,500-5,000 wasps per acre per release. Low
rates of chlorpyrifos were used to reduce California red scale
levels prior to initiating the A. melinus releases.
This program was shown to result in reduced pesticide use
and similar, if not higher, fruit quality and economic returns
compared with the conventional broad-spectrum pesticidebased program.
Several earlier research advances from the UC Riverside
Entomology Department and UC IPM Program were key
for the development of the SJV biologically-based citrus
IPM program. Guidelines proposing economic thresholds
and sampling methods for the lepidopterous pests on citrus,
which are collectively referred to as “orangeworms”, were
developed. T.S. Bellows and J.G. Morse determined the toxicity and persistence of commonly used pesticides to important
citrus natural enemies, thus facilitating the choice of selective materials that could be used in the program. J.D. Hare
documented that citrus red mite (Panonychus citri) economic
thresholds used in Southern California were too low for application in the SJV and that SJV populations seldom resulted
in reduced yield. D.S. Moreno and R.F. Luck documented
the efficacy of augmentative releases of A. melinus against
California red scale in Southern California, setting the stage
for augmentative release strategies in the SJV. Working with
FMC Corp., G.P. Walker, Morse, and M.L. Arpaia adapted
technology from South Africa and Israel and showed that a
high-pressure postharvest washer was effective in removing
California red scale from fruit, thus allowing the economic
threshold of this key pest to be elevated.
Although research efforts were critical, the biologicallybased IPM program would not have been adopted in the San
Joaquin Valley without extension education (Photo 6) and
the dedication of many progressive citrus growers and pest
control advisors.
Photo 6. Tulare County UCCE Farm Advisor Neil O’Connell
conducting a field day training on citrus IPM. Photo by Beth
Grafton-Cardwell.
Photo 7. UCR Entomologist Dr. Robert Luck (second from left) teaching growers and PCAs about biologically-based IPM.
Photo by Beth Grafton-Cardwell.
A number of grower meetings were held at the Crown
Butte ranch in the late 1980s to present and discuss progress
in development of the IPM program (Photo 7). Throughout
the 1990s, yearly workshops were held to teach pest control
advisors how to recognize the life stages of California red
scale, their parasitoids, and how to determine if biological
control was successful. Field days and video tapes on citrus
thrips and orangeworm monitoring were produced.
In addition, yearly roundtable discussions were jointly
sponsored by UC Extension Specialist E.E. Grafton-Cardwell
and the Association of Applied IPM Ecologists. In these discussions, pest control advisors shared information about pest
pressures, monitoring methods, control tactics, and the level of
success of biological control they had achieved. Smith-Lever
and Citrus Research Board funds supported demonstration
projects in Kern and Tulare counties that sampled pest and
natural enemy densities in orchards utilizing biologicallybased versus pesticide-reliant strategies.
Data on pest densities, natural enemy levels, degree-days,
and the consequences of various pest management strategies
in these orchards were discussed by extension personnel in
grower meetings, provided as a newsletter, and posted on
a citrus entomology Web site at the Kearney Agricultural
Center. Organizations such as Paramount Citrus took a lead
role in studying and transferring high-pressure postharvest
washer technology from South Africa to San Joaquin Valley
packinghouses. All of this activity helped to increase grower
adoption of biologically-based IPM methods.
Adoption of the biologically-based citrus IPM program in
the SJV was initially slow but was accelerated by the development of pesticide resistance in two key pest species. Citrus
thrips has a history of developing resistance to broad-spectrum
pesticides used extensively for its control and, following the
appearance of dimethoate resistance in 1980, formetanate
resistance in 1986, and cyfluthrin resistance in 1996, growers
became increasingly motivated to use a biologically-based
approach in managing this pest.
Of greater impact, however, was the appearance of
California red scale resistance to organophosphate and
carbamate insecticides in the SJV in 1990. Because no new
effective chemical options were available to growers with
pesticide-resistant California red scale, and because multiple
applications of organophosphates and carbamates were so
costly (ca. $160/acre per treatment), grower adoption of the
biologically-based citrus IPM program accelerated in the early
1990s and reached a peak in 1997 with participation of an
estimated 10-25% of SJV growers (this estimate varies based
on who one talks to and what one considers the threshold for
“participation”, i.e. does one include only those that relied
very heavily on Aphytis releases to help manage red scale
with only very occasional pesticide use).
Impediments to adoption of biologically-based IPM;
shifts in insecticide use change the status of some pests
In 1998, because of increasing problems with California
red scale resistance, the insect growth regulators pyriproxyfen
(Esteem or Knack) and buprofezin (Applaud) were made
available to SJV citrus growers through a Section 18 Emergency registration with full registration in 2000 and 2002,
respectively.
Pyriproxyfen was extremely effective against California
red scale, but unfortunately was initially quite disruptive to
coccinellid predators such as the vedalia beetle (critical to
cottony cushion scale control) and Rhyzobius (Lindorus)
lophanthae, an important predator of California red scale.
In South Africa, pyriproxyfen use led to mealybug flare-ups
in untreated groves located near groves where it was used
(the pesticide was sufficiently active to suppress mealybugs
in treated groves but coccinellid predators which normally
maintained mealybugs below economic levels were suppressed regionally).
Similarly, in California, dramatic cottony cushion scale
flare-ups were observed starting early in 1999 in biologicallybased citrus IPM blocks near groves using pyriproxyfen
because of its toxicity to vedalia beetles. Unfortunately for
California growers, malathion, methidathion (Supracide), and
carbaryl (Sevin) were the only effective insecticides available
for cottony cushion scale control, and these materials are
highly toxic to natural enemies, such as A. melinus, needed
for control of other pests.
Based on experience from Israel and South Africa, California researchers were aware of the potential for secondary
pest upsets if pyriproxyfen was used on California citrus. In
May 1996, at the Seventh International Citrus Congress in Sun
City, South Africa, a number of citrus growers and researchers
listened to an impassioned talk by V. Hattingh and B.A. Tate
describing upsets of mealybugs and cottony cushion scale
which resulted from pyriproxyfen treatments in South Africa.
Subsequently, six meetings of growers, pest control advisors, and researchers were held in 1997 at various sites in the
SJV to discuss the likely benefits and detriments of requesting
the Section 18 use of pyriproxyfen. Despite concerns raised
about possible secondary pest upsets, the consensus at those
meetings was that this insecticide was needed to deal with
increasing populations of California red scale and the escalating use of organophosphate insecticides.
As predicted, severe cottony cushion scale outbreaks were
experienced in 1999-2000. Subsequent research by GraftonCardwell on vedalia beetle activity demonstrated that it is
most effective in the spring and activity declines with summer
heat. She then trained growers to delay use of pyriproxyfen
until after vedalia had completed its springtime control of
cottony cushion scale. Cottony cushion scale is now a sporadic secondary pest because of careful use (timing) of what
Photo 8. Third instar katydid nymph on a new fruit, ready to
begin feeding. Photo by Beth Grafton-Cardwell.
otherwise can be a highly disruptive insecticide.
The availability of pyriproxyfen, a very effective red scale
control material, dramatically lessened interest in adopting
the biologically-based IPM program for SJV citrus because,
initially, this insecticide could be applied for red scale control
every second or third year if red scale levels were not high.
This is quite common when a new and effective pesticide is
introduced – initially, it can be remarkably effective (e.g., DDT
against many pests, parathion-red scale, dimethoate-citrus
thrips). In addition, there is a perception that use of biological
control is riskier and more difficult to employ compared with
a traditional chemical control program.
For the present, many growers will continue to rely on
pyriproxyfen for California red scale control, but we are beginning to see the early stages of resistance in some areas. In 2008,
spirotetramat (Movento) was registered for California red
scale control, and rotating its use with pyriproxyfen will help
with managing resistance to either product. Both pyriproxyfen
and spirotetramat are soft on parasitoids such as Aphytis, so
they have allowed more natural biological control of California red scale to occur, minimizing the frequency of use of
either product and providing longer term control of this pest.
Soft insecticides release secondary pests from control
At about the same time that pyriproxyfen and buprofezin
were registered for California red scale control, spinosad was
registered for citrus thrips control. All three of these insecticides showed greater safety for most natural enemies (other
than coccinellids-pyriproxyfen and buprofezin) and greatly
improved worker safety because of their specificity for certain pest groups because they replaced organphosphate and
carbamate insecticide use.
There was a problem, however, with greater selectivity
allowing several secondary pests to become primary pests.
Citricola scale and forktailed bush katydid (Scudderia furcata) (Photo 8) were quite susceptible to organophosphates.
They were easily suppressed by treatments for citrus thrips
and California red scale during the “pesticide era”. The insect
growth regulators used for red scale are not very effective
against citricola scale. The spinosad treatment (and later
spinetoram [Delegate]) for citrus thrips has a relatively short
residual period of activity and thus is not effective in years
with a prolonged hatch of katydids or when used against the
larger katydid instars. With the reduction in organophosphate
and carbamate use, these insects have become chronic pests.
In the San Joaquin Valley, biological control agents for these
pests do not keep them below economic levels.
In response to increased katydid densities (Photo 9), growers are tank-mixing low rates of pyrethroids or organophosphates with the spring spinosad or spinetoram treatment for
citrus thrips control. Low rates of broad-spectrum insecticides,
applied in low water volume (100-200 gpa) to the outside of
the tree during spring, are fairly well tolerated by most natural enemies. Thus, these treatments can control katydids and
minimize the impact on biologically-based IPM.
The insect growth regulator diflubenzuron (Micromite)
and stomach poison cryolite (Kryocide) are slow-acting, but
they are selective and can be used before petal fall to control
katydids prior to their causing damage on fruit. Cyantraniliprole (Altacor) was also recently registered and is fairly
selective. Thus, katydids can be managed through low rates
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of a broad-spectrum material or via selective insecticides.
Citricola scale has become a serious problem in the San
Joaquin Valley because of inadequate biological control (except in groves with brown soft scale) and the low threshold
for the economic damage it causes (lowered yield and sooty
mold production). This scale has only one generation per year
and long periods of time when citricola scale size is too small
for use by several species of parasitic wasps that devastate
the scale in Southern California. In addition, most areas of
the San Joaquin Valley appear to lack alternative hosts of the
parasitoids such as black scale and brown soft scale.
Initially, growers managed increases in citricola scale
(Photo 9) in the SJV biologically-based program with low rates
of chlorpyrifos (Lorsban). Many natural enemies of citrus
pests have developed tolerance to low rates of organophosphates, especially chlorpyrifos, due to repeated exposure, and
thus, these treatments are now considered fairly compatible
with IPM if they occur relatively infrequently (no more than
once a year).
However, as citricola scale became a common pest of citrus
in the 2000s, continued use of chlorpyrifos led to resistance in
about 40% of citricola scale populations, with even high rates
of chlorpyrifos failing to suppress the scale below economic
levels for more than a single year.
Growers began to use foliar neonicotinoids (imidaclo-
Photo 10. UCR Extension Specialist Beth Grafton-Cardwell
utilizes a mobile laboratory to teach about scale pest
management. Photo courtesy of Beth Grafton-Cardwell.
prid [Provado] and acetamiprid [Assail]) for citricola scale
control; however, this chemical group is highly toxic to most
natural enemies, reducing the success of the biologicallybased program. Growers also used imidacloprid systemically
to control citricola scale and reduce the impact on natural
enemies. That formulation, however, is also toxic to natural
enemies and only weakly suppresses citricola scale. The IGR
buprofezin (Applaud) can be effective against ctiricola scale
and is soft on parasitic wasps, thus it is a selective insecticide.
However, both foliar neonicotinoids and buprofezin require
direct contact to kill the scale, and thus coverage is critical.
These insecticides do not reduce scale densities to levels as
low as the organophosphates did before resistance became
a problem, and they need to be used every one to two years.
The current trend is that growers alternate selective
insecticides (pyriproxyfen, buprofezin, and spirotetramat)
for California red scale control with an organophosphate or
neonicotinoid insecticide treatment for citricola scale so as
to minimize costs and reduce the impact of broad-spectrum
treatments on natural enemies.
Ideally, a selective pesticide is one that reduces the target
pest population below economic levels with limited impacts
on important natural enemy species. In some cases, nonselective pesticides can be used in a selective manner based
on when or how they are used.
Photo 9. Heavy populations of citricola scale reduce yield of
trees and produce honeydew that fosters sooty mold. Photo
by Beth Grafton-Cardwell.
Changes in pesticide practices have caused a shift in pest
pressures in the San Joaquin Valley. The softer insecticides
used for California red scale and citrus thrips have resulted
in a decline of these pests. Citricola scale is now the most
common and most difficult pest to control, requiring the use
of broad-spectrum insecticides that disrupt the biologicallybased IPM program. New selective insecticides for citricola
scale are needed to allow natural enemies affecting other
pests to flourish.
Meanwhile SJV growers continue to be educated in monitoring methods, using treatment thresholds, and are averaging
three to four pesticide treatments per year. Again, University
of California extension programs and Citrus Research Board
education in the form of grower seminars, field days, a mobile
laboratory (Photo 10), Citrograph articles, online courses
(http://classes.ucanr.org), and Web sites (www.ucanr.org/sites/
KACCitrusEntomology/, http://www.ipm.ucdavis.edu/PMG/
selectnewpest.citrus.html and www.citrusresearch.org) help
growers and PCAs to stay informed and maintain biologicallybased IPM if they are interested in that approach.
In spite of all of the recent pest and program changes, a
number of growers and pest control advisors continue to use
the biologically-based IPM program in the SJV, often adapting
it based on their experience and the local situation. Based on
sales information provided to us confidentially by producers
and suppliers of Aphytis melinus, we estimate that ca. 1,410.8
million and 1,338.5 million Aphytis were sold to SJV users
in 2010 and 2011, respectively. Practitioners likely used a
minimum of 20,000 Aphytis per acre per year (in this case to
augment mostly chemical red scale control) and as many as
130,000 Aphytis per acre per year (on organic citrus). If we
estimate that the mean per acre Aphytis use is somewhere
between 40,000 and 80,000 wasps per acre per year, then the
above sales figures translate to between 17,246 - 34,492 acres
in the San Joaquin being treated on average per year with
Aphytis over the 2010 and 2011 seasons.
Exotic pest introductions disrupt biologically-based IPM
A second problem for growers using biologically-based
citrus IPM in the SJV (and anywhere else for that matter) is
the introduction of new (exotic) pest species (Table 1). The
rate of new introductions appears to be increasing, partially
because of greater movement of people and plant material
between states and countries but also because of reduced
vigilance at border entry points brought about by an emphasis
on facilitating trade.
When exotic pests enter a new region, they often arrive
without the full complement of natural enemies present in
their native range. Thus, chemical control is often needed to
maintain damage below economic thresholds until the full
natural enemy complex is introduced and provides adequate
control.
An example of a recent exotic invader is the glassy-winged
sharpshooter (GWSS). GWSS live on citrus, as well as many
other hosts, and vector various strains of the bacterium Xylella
fastidiosa that cause Pierce’s Disease in grapes, almond leaf
scorch, alfalfa dwarf, oleander leaf scorch, and several other
diseases such as citrus variegated chlorosis and phony peach
disease that are not yet present in California.
Because this pest is so destructive to the grape industry,
citrus growers are asked to control GWSS in their plantings
to reduce the potential movement of Xylella into nearby
grapes. The insecticide group of choice for this pest is the
neonicotinoids, which can potentially disrupt natural enemies.
The current GWSS treatment program attempts to reduce the
impact of the neonicotinoids by applying them systemically
or if as a foliar spray, waiting until late in the season.
Other arthropod pests have also entered the state recently, and many of them require insecticide treatments, at
least initially. The red imported fire ant (RIFA) (Solenopsis
invicta) was found in February 1997 in Kern County, and
eradication with soil treatments of pyrethroids has been
attempted. Since then it has also shown up in large areas of
Southern California. At present it is unclear whether RIFA
populations will be eradicated in the SJV, but it is possible
that this pest may eventually become established and spread
into citrus groves there.
The citrus leafminer (Phyllocnistis citrella) was discovered in Imperial County in southernmost California in
January 2000, spread to Riverside Co. in 2002, and is now
found throughout much of California. The citrus peelminer
(Marmara gulosa) is well established in parts of California
but has changed its habits, likely due to the recent introduction of a new biotype from Mexico in the late 1990s, and can
cause extensive fruit damage to susceptible citrus varieties
such as pummelos, grapefruit, and various navel oranges
(especially Fukumoto, Atwood, and TI). Fortunately, the
potential for biological control by parasitoids of citrus
leafminer and citrus peelminer on bearing citrus is good,
and thus these pests have not caused a major increase in
insecticide use. For citrus leafminer, young plants require
multiple insecticide treatments to maximize growth. Pheromone disruption methods are being developed to manage
citrus leafminer in nurseries.
Diaprepes root weevil (Diaprepes abbreviatus) was discovered in Southern California in 2005, and the larval stages are
known to be a threat to the root systems of citrus and other
crops, largely because they worsen the impact of soil diseases
such as Phytophthora. Eradication of Diaprepes was initially
attempted, but in part due to the State’s fiscal situation, this
was discontinued in 2008. If it spreads to commercial citrus
production areas, it will require several treatments a year,
including several broad-spectrum insecticides such as pyrethroids and neonicotinoids, potentially disrupting IPM and
Table 1. Exotic pests recently invading California citrus.
Common name
Scientific name
Damage
Detection in California
Glassy-winged sharpshooter
Homalodisca coagulata
Vector of Pierce’s Disease in neighboring grapes Reduced fruit production in citrus exposed to extremely high densities
Mid 1990s
Red imported fire ant Solenopsis invicta
Damage to young plantings of citrus
Human health hazard
1997
Citrus peelminer (Mexican strain) Marmara gulosa
Reduction in pack-out due to mining of the rind of susceptible varieties
1998
Citrus leafminer
Phyllocnistis citrella
Attacks new foliage, can reduce growth of plants in nurseries and new plantings
2000
Diaprepes root weevil
Diaprepes abbreviatus
Larvae attack the root system of citrus trees making trees more vulnerable to pathogens
2005
Asian citrus psyllid
Transmits the bacterial pathogen that causes huanglongbing
2008
Diaphorina citri
greatly increasing costs to growers.
The impacts of the above exotic pests are likely to appear mild in comparison to the Asian citrus psyllid (ACP), in
particular if the bacterial disease it vectors, huanglongbing
(HLB), is found in California.
HLB is moving northward towards California from
Mexico and was recently discovered in commercial citrus in
Texas. This disease has had serious impacts on citrus production in China, Brazil, Florida, and elsewhere and has been the
subject of many recent Citrograph articles. Thus, we will not
address ACP and HLB in detail here other than to say that
experience in Florida has clearly shown that to-date, the most
effective strategy of managing HLB is via effective, regional
insecticide treatment programs for ACP, which ideally include
all commercial growers in the region.
We still have much to learn about adapting the experience with ACP and HLB management from other states and
countries for optimal use in California. In the long term, we
are optimistic that research will develop a practical solution to
ACP and HLB management that does not require continual
broad-spectrum pesticide applications and maximizes the
use of biological control of ACP to the extent that is feasible.
Because of the severity of HLB, in the interim, we may go
through a rocky period as we learn how to best deal with ACP
and determine what sort of chemical program will cause the
least impact on natural enemies and the upset of secondary
pests that often results. If we can weather the ACP-HLB storm,
we believe biologically-based IPM holds tremendous promise
regarding the future of citrus pest management.
It is important to note that the level to which a particular
grower and/or pest control advisor adopts biologically-based
citrus IPM varies tremendously across the SJV and, in reality, there is a spectrum of adoption varying from those who
emphasize biologically-based IPM by severely limiting the use
of pesticides which impact natural enemies to those who rely
heavily on chemical control and are not as concerned with the
occasional use of broad-spectrum pesticides.
Most growers and pest control advisors are in the middle
of this spectrum and would adopt biologically-based IPM
to a greater degree if some of the more difficult challenges
to this approach were solved (e.g., selective management of
citricola scale, citrus peelminer on some varieties, and ACP
once it enters the SJV).
Conclusions
Successful Biologically-Based IPM and Impediments to
its Adoption and Success:
1. The success of the program depends on intensive
sampling of pest and natural enemy populations in order
to maximize the effectiveness of soft pesticides and natural
enemy populations.
2. Developing the required level of knowledge and training
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needed to successfully conduct biologically-based IPM for a
crop system as complex as citrus takes years of experience
and input from knowledgeable pest control advisors and
supportive growers.
3. There is a learning curve associated with the adoption
of biological-based IPM in the SJV, and the “system” does not
stabilize for a year or two after the conversion from an IPM
program based more on pesticide use. To make the program
work effectively, a commitment to biologically-based IPM
is needed by knowledgeable growers and their pest control
advisors.
4. The biologically-based citrus IPM program is both
sustainable and dynamic, due to changes in pesticide registrations, pest complexes, and the introduction of exotic species.
Research, extension, and management programs have to be
equally dynamic to respond to those changes.
For the immediate future, further adoption of the biologically-based citrus IPM program in the SJV depends on the
motivation of growers and PCAs who are interested in this
approach. Unfortunately, this approach is likely to become
more difficult, rather than easier, once the industry has to
deal with the presence of ACP (and hopefully much later,
HLB) in the SJV.
For some people, an IPM program emphasizing chemical
pest control appears to be a simpler pest management solution, and this approach may be absolutely essential to effectively dealing with ACP and HLB. However, experience with
citrus has shown that this approach is not sustainable over the
long term (pesticide resistance being one recurring problem)
and is more costly than biologically-based IPM.
Acknowledgments
Development of the biologically-based citrus IPM program for SJV citrus would not have been possible without
the input and assistance of a large number of individuals and
agencies. Robert F. Luck; Harry Griffiths and Joe Barcinas of
Entomological Services, Inc.; Frank Marshall of Central Valley
Management, Inc.; Neil O’Connell, UC Cooperative Extension, Tulare County; Craig Kallsen, UC Cooperative Extension
Kern County; Lisa Forster, Phil Haney, and Alan Urena of UC
Riverside; the UC Riverside Entomology staff at the Lindcove
Research and Extension Center (Ashley Derr, Janine Lee,
Janet McClain, Melissa O’Neal, Yvonne Rasmussen, and Chris
Reagan) and the Kearney Ag Center (Ping Gu, Greg Montez,
Yuling Ouyang, Becky Striggow, and Stacy Vehrs); and Jim
Stewart and Jim Gorden of Pest Management Associates,
Inc. were all instrumental in helping to develop this program,
as was funding provided by the California Citrus Research
Board, the UC Statewide IPM Program, Smith-Lever funds,
the California Energy Commission, and the USDA Office of
International Cooperation and Development.
This article is an update of a 2006 article that was published
in the UC Plant Protection Quarterly.
Dr. Joseph G. Morse is a Professor of Entomology with
the Department of Entomology, University of California
Riverside. Dr. Beth Grafton-Cardwell is a University of California Extension Specialist and Research Entomologist. She
is a Citrus IPM Specialist in the Department of Entomology
at UC Riverside and also serves as Director of the Lindcove
Research and Extension Center. l
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What are the University of California sources for
citrus integrated pest management information?
Beth Grafton-Cardwell
T
he University of California Integrated Pest Management Program
(UC IPM) provides hundreds of
pages of excellent information in print
form and on the Web that explains how to
recognize and manage pests and diseases
of citrus.
Below I discuss the three major components of these guidelines and their uses.
While the citrus manual and guidelines
have been around for decades, and most
growers and PCAs are familiar with
them, the Year-Round IPM Program for
Citrus approach is less well-known, but
extremely useful, especially for those
who are new to citrus. I encourage you to
explore these pages.
Citrus IPM Manual - NEW THIRD
EDITION Available March 2012!
The previous edition of the Citrus
IPM Manual was published in 1991. The
new edition incorporates changes in our
knowledge of various endemic vertebrate,
weed, nematode, insect and mite pests
and diseases and introduces a number of
recently invading species.
During the past 15 years, glassywinged sharpshooter, citrus leafminer, a
new strain of citrus peelminer, diaprepes
root weevil and Asian citrus psyllid have
established in California. In addition, the
manual provides photos of a number of
diseases that have not yet reached California, including citrus bacterial canker,
huanglongbing, citrus variegated chlorosis
and citrus leprosis.
The new edition emphasizes photorecognition of citrus pests and diseases and
is an essential manual for the library of anyone with an interest in citrus management.
Fig. 1. A snapshot showing a portion of the available information in the UC
IPM Citrus Pest Management Guidelines. http://ucipm.ucdavis.edu/PMG/
selectnewpest.citrus.html
UCIPM Citrus Pest Management
Guidelines http://www.ipm.ucdavis.
edu/PMG/selectnewpest.citrus.html.
The UCIPM citrus pest management
guidelines provide information on all of
the significant pests and diseases of citrus
(Figure 1). For each pest or disease, the
guidelines describe its lifecycle, the damage it causes to citrus, natural enemies that
attack it, monitoring methods, organically
acceptable methods of control, selectivity
Fig. 2. A snapshot of the first page of the year-round IPM program for Central
Valley citrus. http://ucipm.ucdavis.edu/PMG/C107/m107yi01.html
of pesticides, resistance issues and pesticide
treatment choices.
It is an excellent reference source for pest
control advisors and growers to make decisions about when to treat and what to treat
with. The guidelines also have important
links to pages such as “mandatory intervals
between application, reentry (REI), and
harvest (PHI) and hazards to bees”. This
section is very helpful as a quick check for
which pesticides are registered for citrus as
well as their use restrictions.
UCIPM Year-Round IPM Program for
Central Valley Citrus
http://www.ipm.ucdavis.edu/PMG/C107/
m107yi01.html
In 2008, University of California farm
advisors, extension specialists and researchers worked with UC IPM to develop a “YearRound IPM Program for Central Valley
Citrus” (Figure 2). The year-round program
provides perspective on when activities
should occur during the year (pre-bloom,
bloom, petal fall, fruit development and fall).
For example, during the pre-bloom
period, PCAs are advised to monitor for
California red scale, mites, cottony cushion
scale, earwigs, katydids and brown garden
snails. They are also advised to watch for
Fig. 3. The annual checklist for the citrus year-round IPM program. http://
ucipm.ucdavis.edu/PMG/C107/citrus-checklist.pdf
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Fig. 4. The forms and photo identification pages for the citrus year-round IPM
program. http://ucipm.ucdavis.edu/PMG/C107/m107yiformsphotos.html
diseases such as bacterial blast, brown rot,
dry rot, and Phytophthora as well as survey
winter weeds and search for signs of vertebrate pests.
For each of these pests or diseases, the
details of how to monitor are provided using
links to text, photos, and monitoring forms.
The photos and monitoring forms (Figure
4) are easily downloaded and printed. The
monitoring forms are especially helpful for
PCAs new to citrus, providing consistent
methods of sampling that allow orchard pest
and disease populations to be compared.
The Citrus Year-Round IPM Program
also includes an 8-page annual checklist
that can be printed out and used throughout
the year. The checklist is an excellent way
to demonstrate to regulatory agencies and
employers that you are using integrated
pest management tactics to manage pests
and diseases.
A University of California Extension
Specialist, Dr. Beth Grafton-Cardwell is a
Citrus IPM Specialist in the Department of
Entomology at UC Riverside and serves as
the Director of the Lindcove Research and
Extension Center, Exeter. l
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CRB 2011 Annual Report
Ted Batkin, President
T
he 2011 fiscal year brought about several
changes and also some degree of stability.
First, the program changed the fiscal year
from 1 November to 1 October. This resulted in an
11-month year, so many of the figures in the budget
report are a bit different from a normal 12-month
year. Second, the Operations program is in its third
year, so there is a level of stability in that program and
the work is going smoothly. The Operations program,
which is funded through a contract with the Citrus
Pest and Disease Prevention Program (CPDPP),
remains focused on maintaining a strong Asian citrus
psyllid detection program in commercial groves and
laboratory testing for HLB.
For the research program, advances were made in
the development of an ACP trap with some level of
attractant. This work is now at the field-testing stage,
and several of the compounds are showing promise
to improve the traps. In the area of diagnostics, the
year brought notable progress in the VOC detection
system and the Lateral Flow Microarray device. Both
of these platforms are moving towards commercialization and should be available to the industry within
the next two years. ACP control still is a focus of the
research agenda, and several new projects were initiated to help with field efficacy issues.
The Jerry Dimitman Laboratory in Riverside is
now fully certified by USDA-APHIS and processing
both leaf samples and ACP samples for the presence of the bacteria associated with huanglongbing.
In addition, the Board completed an expansion of
the facilities to improve the capacity for sample
processing and to provide room to conduct methods
development from CRB-funded research projects.
The Board welcomes your comments and observations to the Citrus Research Program. The
following table lists the audited financial statement
for the 2011 fiscal year. A complete copy of the audit
is available for viewing at the CRB office at 217 N.
Encina, Visalia, CA. You are welcome to visit us at
any time to discuss any elements of the program and
see what we are doing. This is your program, and we
look forward to hearing from you. l
CITRUS RESEARCH BOARD
November 1, 2010 through September 30, 2011
INCOME
2010-2011 FY Assessment Income................ 5,928,276
Prior Season Income......................................... 144,197
Investment Interest Income................................. 26,527
Investment Dividend Income............................... 21,087
Rent..................................................................... 2,117
Citrograph Advertising........................................ 27,874
Conference Registration Fees............................. 11,183
Outside Income................................................. 125,000
Grower Seminar Registration................................ 8,770
Reimbursed Expenses...................................... 137,500
CPDPC Reimbursement Income..................... 2,744,585
TOTAL FUNDS AVAILABLE...........9,177,116
EXPENSES
RESEARCH PROGRAM
Plant Management
DMS VOC Sensor for Citrus............................... 270,000
Bio Sensor Development for
Citrus Disease Diagnosis.................................. 114,887
Determination of Timing...................................... 28,000
Total Plant Management................................ 412,887
New Varieties
Citrus Rootstock Evaluation............................... 111,191
Variety Evaluation for Trueness........................... 71,823
New Citrus Breeding......................................... 163,406
Evaluation of Desert Lemons............................... 13,006
Unforbidden Fruit: Preventing Citrus Smuggling...... 4,884
Total Plant Improvement............................... 364,310
Plant Pathology
Septoria Spot of Citrus.........................................45,375
Small RNA for HLB Plant Response....................104,769
Investigation of Seedling Yellows Cross................69,540
Identification of Spiroplasma citri.........................58,600
Investigating Important Disease...........................82,249
Integrated Low Cost Nucleic Acid.......................151,448
Development, Validation & Deployment..............245,000 Rapid Identification of Unknown Viroid.................75,217
Avoiding Economic Losses in CA Citrus................48,092
Total Plant Improvement............................... 880,290
Entomology
Pest Management Infrastructure....................... 187,871
Management of Thrips........................................ 69,692
Assessment of Systemic Neonicotinoid............. 128,502
Molecular Systematics of Diaphorina.................... 8,092
Optimization of Imidacloprid Application Rates.... 36,700
Host Specificity Testing of Tamarixia................... 74,929
Preparation for Citrus Leprosis............................ 25,205
Evaluation of Oils.................................................. 6,250
ACP Attractants................................................. 288,853
Development of Pathogen Dispenser to
Control ACP...................................................... 114,400
Optimizing Chemical Control of ACP in CA......... 102,603
Maintenance of Foundation ACP............................ 8,226
Total Entomology......................................... 1,101,323
Post Harvest
Treatment Evaluation.......................................... 47,250
New Technologies to Minimize P.H. Decay........... 50,000
Ethyl Formate Studies for Bean Thrips................. 63,945
Breaking Citrus Trade Barriers............................ 26,243
Assessing Factors Influencing Post Harvest Quality. . 55,758
Total Post Harvest.......................................... 243,196
TOTAL RESEARCH PROGRAM...................... 3,002,006
COMUNICATIONS PROGRAM Core Grower Education Program..........................33,543
Citrograph.........................................................103,848
Website.................................................................9,109
CPDPP Outreach Program..................................674,164
Salaries & Benefits - Communications...............181,456
Supplies................................................................1,051
Travel....................................................................1,559
TOTAL COMMUNICATIONS PROGRAM......... 1,004,730
Field
Salaries & Benefits – Field................................ 192,127
Contracts (Outside Personnel)............................... 8,108
CASS Staffing................................................... 479,335
Trap Readers...................................................... 92,406
Travel & Mileage . .............................................. 15,153
Fuel.................................................................... 93,870
Vehicle Repairs & Maintenance........................... 35,571
Equipment Repair & Maintenance......................... 4,652
Supplies............................................................. 99,058
Phone................................................................. 16,493
Postage................................................................ 2,824
Total Field.................................................... 1,039,597
Administrative Support....................................................91,667
TOTAL OPERATIONS PROGRAM................... 1,731,260
PAYROLL EXPENSE – Communications, Operations & Admin................... 93,144
CALIFORNIA CITRUS QUALITY COUNCIL (CCQC)
CCQC Administration......................................... 251,310
Registration Projects........................................... 20,660
International Issues........................................... 152,450
Other Projects..................................................... 11,466
TOTAL CALIFORNIA CITRUS QUALITY COUNCIL (CCQC)............................................. 435,886
CONFERENCES..........................................29,620
GENERAL AND ADMINISTRATIVE
Salaries & Benefits – Administration................. 522,615
Audit Fee............................................................ 12,817
Equipment Repair & Maintenance......................... 3,613
Equipment Rental................................................. 1,916
CITRUS CLONAL PROTECTION PROGRAM
Information Services........................................... 37,898
Core Citrus Clonal Protection Program...............386,403 Insurance & Bonds.............................................. 19,829
LREC Positive Pressure Greenhouse...................144,772
Workman’s Compensation Insurance.................. 10,458
TOTAL CITRUS CLONAL Office Supplies................................................... 20,479
PROTECTION PROGRAM................................. 531,175
Postage................................................................ 5,711
Printing............................................................... 10,496
OPERATIONS PROGRAM
Rent & Storage................................................... 21,400
Data Management
Research Consultant........................................... 10,000
Salaries & Benefits – Data Management........... 140,685
Meeting Costs..................................................... 37,269
Travel & Mileage................................................... 1,343
Telephone........................................................... 17,844
Training................................................................ 1,495
Travel & Mileage – Consultant................................. 935
Information Services......................................... 121,505
Travel & Mileage – Members.............................. 45,541
Supplies.................................................................. 834
Travel & Mileage – Staff...................................... 57,146
Phone................................................................... 2,166
Vehicle Maintenance & Fees.................................... 663
Total Data Management................................. 268,028
CDFA – Bureau of Marketing............................... 52,558
Laboratory – Riverside & Visalia
CDFA – Handler Audit.......................................... 23,625
Building Repairs................................................... 2,456
Salaries & Benefits – Lab.................................. 151,773
Property Taxes...................................................... 4,840
Travel & Mileage................................................... 4,422
Utilities............................................................... 10,538
Equipment Repairs............................................. 10,215
Depreciation..................................................... 180,660
Supplies........................................................... 100,197
Utilities............................................................... 14,121
TOTAL GENERAL & ADMINISTRATIVE............1,111,307
Phone................................................................. 14,158
TOTAL EXPENSES.................................7,939,137
Postage................................................................... 179
TOTAL
CASH
RESERVES...................................2,756.653
Rent.................................................................. 36,911
TOTAL ASSETS.......................................................5,160,450
Total Laboratory – Riverside & Visalia........... 331,976
Citrus Roots
Preserving Citrus Heritage Foundation
California Citrus
Spurred Colonization–
Help! Can you identify the
packer and the location?
Aided Through the
University of California...
Richard H. Barker
Your Foundation through the work of Tom Pulley
is compiling a list of citrus brands of each packer… A FIRST! We have listed 6,870 so far, and we
are still going. We want to match a packinghouse
photo to the majority of the packers on this list,
and that is where you enter!
WE NEED YOUR HELP IN FINDING PHOTOS
OF CITRUS PACKERS IN
Delano
Dinuba
Dixon
Edison
Exeter
Fairoaks
Hamilton City
Ivanhoe
Lemon Cove
Lindsay
Orange Cove
Orosi
Oroville
Palermo
Porterville
Rocklin
Seville
Strathmore
Terra Bella
Visalia
Woodlake
Check out our website…
www.citrusroots.com
Our “Mission” is to elevate the awareness of
California citrus heritage through publications, education, and artistic work.
We are proud of our accomplishments as a volunteer organization, which means each donated
dollar works for you at 100% [for we have no
salaries, wages, rent, etc.]. All donations are tax
deductible for income tax purposes to the full
extent allowed by law.
Citrus Roots – Preserving Citrus
Heritage Foundation
P.O. Box 4038, Balboa, CA 92661 USA
501(c)(3) EIN 43-2102497
The views of the writer may not be the same as this foundation.
50 Citrograph March/April
March/April2012
2012
Commendation is given to the University of California’s College of Agriculture for the work of E. W. Hilgard
and for the Demonstration Trains “California Agriculture
Special”and “Frost Education Special”. The latter provided
the opportunity of promoting the Experimental Station for
citrus research… All due to the help of the Southern Pacific
Company... s a prologue, our focus will start when Eugene W.
Hilgard first came to the University of California
in the mid-1870s. He brought a background in geology, mineralogy, chemistry, zoology and botany coupled with
experiences in the central states and Spain.
One would conclude that he was uniquely suited for his
30-year career at the university. As F. Slate described his
personality in his “Biographic Memoir of Eugene Woldelmar
Hilgard (1833-1916)”, “Many have marveled that a fighting
exponent of personal views in the public arena can be radiant of unassuming gentleness at home.”
Eugene Hilgard is remembered because of his pioneering work in California relative to soils -- “alkali-soil” and
“arid fertility.” His initial landmark “call to fame” was his
scientific study presented by soil maps, which were published as part of the 1880 U. S. Census.
As Richard J. Orsi built the “case” in his book “Sunset
Limited - The Southern Pacific Railroad and the Development of the American West 1850-1930”, the University of
California’s College of Agriculture did not have the financial
means, the capacity, or the capability of amassing the data of
this scale, and it was the Southern Pacific which opened their
immense collection for Hilgard to utilize in compiling these
soil studies.
Further, Orsi mentioned that the railroad company
sent a young civil engineer, Norman J. Willson, to work with
Hilgard, and for over three months he conveyed a handcar
over most of their route collecting over 400 specimens and
samples for this study.
Had it not been for the support of the Southern Pa-
A
cific, these maps could not have been completed in such
exactitude. The University’s College of Agriculture would
not have been credited with this exemplary work, and the
Southern Pacific would not have had these noteworthy documents to support their land promotions.
From Hilgard’s successful work, the rail company took
every opportunity to maximize their efforts from his findings. They concluded on having local irrigated demonstration gardens spotlighting trees, shrubs, and other plants
which were adaptable to the soil and climate of each location. The selection was focused on beauty as a means of
market appeal, though most importantly the highlighted
horticulture example they chose to plant had a potentiality
of becoming a high-traffic commodity.
These “gardens” were located in key station areas and
their various hotels. Supporting horticultural material on
behalf of the University of California and the Southern Pacific Company was available at each “garden site.” Those
“gardens” were successful in furthering colonization and
development; one only needs to look at the citrus development in Southern California, the pioneering of citrus in the
Central Valley, cotton in the area of Roseville, alfalfa in the
Imperial Valley, etc.
In the photo of the Southern Pacific Park (garden) in
Pomona, in support of the above, when the train stopped
for loading and unloading the passengers had a short opportunity to stroll and view this narrow, block-long park
and enjoy the beauty of the flowers, the targeted scheme
of planted shrubs, the citrus varieties and other fruit trees.
Brilliant marketing resulted when the University of California, Southern Pacific Company, and the community worked
together.
Politics and the UC budget
Now, with the background of the Prologue, we can turn
our attention to the period of 1900 to 1917, our nation’s
Progressive Period (the interval of Presidents were Theodore Roosevelt to Woodrow Wilson). It was a time when
the middle-class Americans believed that they needed to
restore the government to the hands of the people. Government should be in the interest of the many rather than just
the few. (The aforementioned keeps echoing -- history does
repeat itself!)
Further, one percent of the population owned 50 per-
The Southern Pacific Railroad Park in Pomona. Travelers
could stroll through the narrow, block-long park and view
the special trees, shrubs, and other plants adaptive to the
soil and climate. Various citrus varieties were on-site.
cent of the country’s wealth. With this setting, we can now
obtain a better understanding of the public attitude and
their emotional feelings toward any sizable organization.
Large institutions were looked upon with distrust. The
Southern Pacific Company stood out as the largest corporation in the West.
The University of California was looked upon as powerful -- and as an elitist -- hence, its budget was slashed. These
budget cuts drove the University and the College of Agriculture to Southern Pacific, for each had common-like goals to
develop farm commodities. The programs of the university
to advance “scientific farming” were being totally ignored.
The Southern Pacific Company offered to help by having their local station agents distribute agricultural bulletins and assist in advertising the university forums offered
to farmers. The company even developed programs under
which farmers could take advantage of drastically reduced
fares to attend these meetings offered by the university.
Bringing the farmers to the University of California’s College of Agriculture did not work! The University became
convinced that it had to go directly to the farmer.
A ‘university on wheels’
This was conceived as a “university on wheels” by
Benjamin I. Wheeler, president of the University. He also
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CITRUS ROOTS ... OUR LEGACY
Volume III of III
(Fed. Tax ID # 43-2102497)
Keeping citrus heritage alive in the minds of those living in California through publications, educational exhibits and artistic works
named it “An Evangel Train.” The Southern
Pacific Company mapped the itinerary, made
schedules, worked with community businesses,
farm organizations, etc. Additionally, the rail
agents publicized each visit. The Company also
provided food and sleeping cars plus paid the
bills as reported by historian Orsi in his book
mentioned earlier, “Sunset Limited The Southern Pacific Railroad and Development of the
American West 1850-1930”.
The rolling of the “California Agriculture
Special” demonstration trains covered three
seasons: 1909-1910, 1910-1911, and 1911-1912.
In 1911-1912, which was the peak, the train
traveled between 4,000 and 5,000 miles, made
238 stops, and attracted 102,000 visitors.
This “California Agriculture Special” train
visited practically every town of importance
within the citrus belt of Southern California. G.
Harold Powell gave a presentation at many of
Benjamin I. Wheeler, president of the University of California, is at the
the stops on citrus pests, spraying methods, and center of the group (middle row, fifth from left).
predatory insects used to control insects; additionally, experiments were conducted on new and better Southern California citrus industry was under siege and
hoping for survival! Some estimated a 39 percent loss of
varieties of oranges and lemons.
The “trains” were most important in helping modern- crop, and the total tree loss was very high.
The Southern Pacific and the University of California
ize California agriculture. During the latter tours, women
professors from the Department of Home Economics gave proactively came together, and the cars rolled again, this
discussions on food preparation, labor-saving devices, and time as the “Frost Education Special” to the help of the
grower to minimize long-term damage and to prepare them
public health issues.
The public resentment changed from this spotlighted at- for another, future freeze. The help was through giving adtention. Further, the California legislature took a more posi- vice as to pruning, irrigation, fertilization, and other importive attitude, which resulted in greater allotments of funding tant recommendations.
The schedule included 24 cities starting on February
for programs and buildings.
13th and continuing to February 18th, from 9:00 a.m. to 9:00
A special frost education train
p.m. Newspapers carried very positive wrap-ups of the tour.
During the end of December 1912 and January 1913, a As reported by the Los Angeles Times (February 12, 1913),
devastating freeze struck the citrus areas. The $175 million present were: T. F. Hunt, dean and director; H. J. Webber,
director of the Citrus Experimental Station; E. J. Wickson, ex-dean
and director; W. T. Clark, superintendent of Farmers’ Institute; J. E.
Coit, professor of citriculture; J. S.
Burd, chemist in charge of fertilizer control; and, J. B. Neff, conductor of Farmers’ Institutes for
Southern California.
President Wheeler of the University became a regular speaker,
and General Manager Powell of
the California Fruit Growers Exchange was a party during part
of the trip. Again, all was paid for
by the Southern Pacific Railroad
Company.
Now, what made this a special
opportunity was the fact that the
population of growers widely attended these 24 stops. This gave
the University a perfect audience
to sign a petition and a resolution
calling for the passage of a bill
Railcar exhibit area. One of many.
then pending in Sacramento, the legislation to appropriate
$385,000 to establish a University Experimental Station for
citrus research.
A “golden opportunity” and a “golden ending”! On
December 14, 1914, the University of California approved
Riverside as the site selection. The Mission Inn rang its bells,
and the electrical plant blew its steam whistle for 15 minutes.
This is just another positive story involving two major
players working together to advance the California citrus
industry.
(The complete L.A. Times, Feb. 12, 1913, article on the
“Frost Education Special” will be posted on the Foundation’s website.)
Richard H. Barker is the founder and president of the
Citrus Roots-Preserving Citrus Heritage Foundation. For
a number of years, he has been leading a drive to bring
about a higher awareness of the role citrus played in developing California. Dick is a retired investment banker and
was a third generation Sunkist grower. He has published
four volumes on citrus heritage.
All illustrations for this article were sourced by the author, who writes that he is especially indebted to the staff at
the Bancroft Library at UC Berkeley for their perseverance
in searching their archives for photographs. The photo of the
Southern Pacific Park in Pomona is from the Pomona Public
Library. l
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CRB Funded Research Reports
Research Project Progress Report
Reagentless detection of citrus pathogens using
differential mobility spectrometry (DMS)
Alexander A. Aksenov, William Cheung, Weixiang Zhao, Hamzeh Bardaweel,
Federico Martinelli, Oliver Fiehn, Abhaya M. Dandekar and Cristina E. Davis
H
uanglongbing (HLB) and tristeza (caused by Citrus
tristeza virus [CTV]) are both destructive citrus diseases capable of severely limiting citrus production.
To date, millions of trees throughout the world have been destroyed due to CTV infection alone. In certain areas of south
Florida, the majority of trees in some orchards are known to be
affected by HLB. As such, both diseases represent a significant
burden to the citrus industry across the world, reducing the
quality and the total amount of citrus production annually.
The primary goal of this project is to develop an early-stage, rapid, and non-invasive means of detecting these
pathogens via analysis of the volatile organic compounds
(VOCs) emitted by citrus plants as their metabolism changes after infection. This approach would complement existing
HLB and CTV detection techniques such as real-time polymerase chain reaction (RT-PCR), electron microscopy and
serological testing already in use.
The VOCs emitted by plants are typically associated
with the distinctive aroma of the specific plant species and/or
varietals (e.g. fresh smell of pine forest, jasmine, basil, mint).
The “fresh citrus” smell is mostly
due to presence of terpenes, a class
of organic compounds that are derivatives of the isoprene pathway.
VOCs an indicator of plant health
man nose (e.g. we don’t smell them, but they are still present
at very low amounts). The application of a highly sensitive
method to conduct VOC screening, which will allow us to
detect and identify those trace level VOCs, will open a new
avenue for monitoring overall plant health in many different
biological systems.
Our first approach was to examine this in citrus, given
the acute need of the industry to diagnose and track HLB
spread across infected orchards.
Plants respond to the presence of a pathogen by hostpathogen interactions that result in changes in metabolic activity; some of these changes will affect volatile metabolites,
which in turn will result in an alteration of the emitted VOC
profile. Some VOCs may undergo down- or up-regulation,
and certain metabolites may be associated with particular
stages of the pathogen’s life cycle within the plant host.
Stimulation of VOC production is often described by
use of the term “induced VOC” (IVOC). The detection of
the entire IVOC profile in a fast, reliable and reproducible
manner that will allow the monitoring of plant health will
provide a very valuable tool for the
agricultural industry in general and
the citrus industry in particular.
At the same time, this poses a
formidable challenge. Application
of certain analytical techniques for
VOC detection may be limited due
to low sensitivity, insufficient resolution, high cost, or a lack of portability, which is essential for realtime and in-field measurements.
Differential mobility spectrometry (DMS) is also commonly
known in scientific circles as high
f ield asymmetric waveform ion mobility spectrometry (FAIMS). It is
a very suitable technology for the
outlined challenges associated with
VOC detection in agriculture mentioned previously.
The released VOCs are closely
associated with plant metabolism,
therefore serving as an indicator
of plant health status. The changes
in VOC production can occur due
to a variety of conditions, including changes in environment, water
stress, nutrient status, or the presence of pathogens.
The VOCs typically must be
present in relatively high concentration to reach our human “olfactory
threshold” to be detected by the human nose but in lower concentration
for a dog’s nose. Out of thousands
of chemical compounds released
Use of DMS technology
by plants, most will be present at
The micro-machine DMS is a
concentrations significantly below
very small and portable device that
the olfactory threshold of the hu- Fig. 1. Sampling of VOC using portable DMS unit. has great sensitivity and specificity
and a relatively low power consumption. It functions to de- cation of the DMS has only been around for about 10 years,
tect a large number of volatile and semi-volatile compounds, and a constant stream of developments have already lead to
even at very low concentrations — from parts-per-million the development of units that are briefcase size (Figure 1a)
down to parts-per-trillion thresholds. The DMS technology that can be easily carried by a person. However, the actual
belongs to the family of other ion mobility (IM) chemical size of the “guts” of the DMS sensor is only few millimeters,
detection methods which exploit differences in gas-phase so the potential for further miniaturization is significant.
behavior of ions under various applied electric fields.
In conjunction with portable computing devices such as
The drift time ion mobility spectrometry (DT-IMS) is a the smartphone (e.g. iPhoneTM or DROIDTM) technologies,
very well established technology that is used extensively for the actual field unit may be reduced to a hand-held size in
security applications (e.g. airport screening for explosives and the near future. These units could be easily taken into an
narcotics), military applications (e.g. detection of chemical orchard and used for an on-site measurement by growers,
warfare agents), and other trace compounds detection needs. managers, or regulators.
An additional advantage of the DMS sensing method
The DMS technology utilizes differences in ion behavior
under low and high field conditions for various ionic chemical is its portability. The PCR-based assay for identification of
species, unlike the DT-IMS method where ions are driven by HLB-associated bacteria, which is currently the method of
relatively weak electric fields. In the DMS system we employ choice for the HLB detection, requires sophisticated instruin this study, volatiles are sampled through low-pressure in- mentation and sample processing that can only be done at
the appropriately equipped
let (“sniffing”), ionized, then
regional laboratory. In conpassed between two small
trast, DMS measurements
metal electrodes using an apcan be done on-site and
propriate sampling “carrier”
streamlined with the use of
gas (e.g. dried room air).
dedicated equipment.
A specifically-shaped
For example, an autoradio-frequency (RF) elecmated GPS-controlled rotric field waveform is applied
botic platform carrying sensacross the electrode pair. If
ing unit(s) could be set up
the mobility of a sampled
to scout orchard acreage for
chemical is different under
diseased trees and map their
high- and low-field condilocation with minimal need
tions, the chemical will exfor an operator and/or laboperience net displacement
ratory personnel interactions.
toward one of the electrodes
We have initiated DMS
and will be neutralized (i.e.,
studies of trees infected with
we cannot “see” it). An additional direct current (DC) Fig. 2. An example of DMS data for VOCs produced by orange one of two citrus pathogens,
tree leaves. The left panel shows detected positively charged
voltage, called a “compensa- ions; the right panel shows detected negatively charged ions. Liberibacter spp. and CTV,
using the portable DMS
tion voltage” (CV), is applied
to the RF electrode to offset ion displacement and allow a units. For the HLB studies, the infected or diseased and preparticular chemical species to pass through the device — ef- sumed healthy Hamlin orange trees located in the orchard
at the Citrus Research and Education Center (Lake Alfred,
fectively acting as a filter.
Each chemical species has a unique dependence of its FL) were visually selected by human scouts and confirmed
mobility due to the electric field (chemical signature); there- to be healthy/infected by PCR.
In order to sample a tree, leaves on a branch were placed
fore the differences in ion mobilities under high- and lowin front of the DMS unit’s inlet (Figure 1b) to draw the air
field conditions can be used to identify specific chemicals.
Variation in the amplitude of the asymmetric waveform off the leaf surfaces and into the unit. The chemicals were
will alter ion behavior and may result in different CV. Thus, pre-concentrated on a sorbent trap for a set period of time.
using such amplitude scan in addition to the CV monitor- After that, the trap was heated and desorbed chemicals were
ing allows a significant enrichment of information from each introduced into GC column followed by DMS analysis. The
measurement. This is a critical advantage of the DMS method resultant GC/DMS trace reflects the total IVOC fingerprint
compared to the DT-IMS for the discrimination of extremely for a particular tree (Figure 2).
We have collected DMS data from infected citrus
complex samples such as VOCs off-gassed by citrus trees.
In addition, the DMS can be coupled with other separa- throughout the year to account for seasonal differences in
tion methods such as gas chromatography (GC/DMS), fur- VOC production by the trees. Currently, the data are being
ther increasing diagnostic capability. In a GC/DMS experi- analyzed, and our diagnostic algorithms are being fine-tuned
ment, each chemical can be separated and characterized by for the detection of disease-related volatile “biomarker”
their respective CVs and retention times, both indicative of compounds.
a particular chemical species.
Potential for miniaturization
An important advantage of the DMS technology is its
potential for further miniaturization. The commercial appli-
Data analysis and model development
This year-round sampling period included significant
fluctuations in weather conditions from extremely hot temperatures with high humidity in summer to freezing temperMarch/April 2012 Citrograph 55
atures with lower humidity in winter. A number of trees with
symptoms varying from very mild to severe were included in
the study (health status confirmed by PCR in all cases). This
will allow us to assess feasibility of the DMS-based chemical sensing for early-stage asymptomatic disease detection.
The collected data are being analyzed, and a mathematical
model is currently being developed for the differentiation of
HLB-sick and healthy trees based on our data.
We ultimately seek to identify the chemical compounds
produced by citrus trees and then link the response of our
DMS unit to variations in the production of these particular compounds. To do this, we also sample citrus VOCs using
solid phase micro extraction (SPME) and TwisterTM devices,
in parallel to the portable GC/DMS units.
The SPME and Twister devices have a different design,
but both operate in a similar fashion to each other – offgassed citrus VOCs are adsorbed onto a polymer coating
when the collection devices are exposed to a tree leaf for a
predetermined period of time. Upon heating, the adsorbed
chemicals can be desorbed and introduced into laboratorybased traditional gas chromatography mass spectrometry
(GC/MS) instruments.
This lab analysis will allow us to identify differences in
VOCs production due to pathogen infection and identify
specific “biomarker” compounds using the MS data. An
example of how we perform unique confirmatory chemical
identification using MS is shown in Figure 3.
In the final phase of our study, we are working to link the
production of VOCs to specific gene activity in citrus plants
that is associated with specific chemical signatures or IVOC
biomarkers. Specific genes can be up- or down-regulated in
response to a certain pathogen that in turn result in selected
alterations of citrus metabolism and of the emitted VOCs
that we can observe as off-gassed by the trees. By comparing
healthy and infected trees it is possible to determine when
particular genes were up- or down-regulated. Since one gene
corresponds to a specific protein or an enzyme, it is possible
to conceive of this as an entire network of metabolic activity leading to the production of certain end-product VOCs
based on previously classified metabolic networks.
To date, we have collected leaf samples for deep transcription level sequencing, and these transcriptome analyses
will be carried out along with DMS and GC/MS experiments.
Project Leader Dr. Cristina Davis is an Associate Professor in the Department of Mechanical and Aerospace Engineering, University of California Davis. Co-Project Leader
Dr. Abhaya M. Dandekar is a Professor in the Department of
Plant Sciences, UC Davis, and Co-Project Leader Dr. Oliver
Fiehn is a Professor with the UC Davis Genome Center and
Bioinformatics Program. Dr. Alexander Aksenov is a development engineer, Dr. William Cheung is a postdoctoral fellow, Dr. Weixiang Zhao is an associate specialist, and Dr.
Hamzeh Bardaweel is a postdoctoral researcher, all in the
Bioinstrumentation and BioMEDs laboratory directed by
Prof. Davis. At the time of this work, Dr. Federico Martinelli
was a postdoctoral fellow in the Dandekar laboratory, UC
Davis Department of Plant Sciences.
CRB research project reference number 5100-135. l
Sabinene
Fig. 3. Identification of chemical compounds from GC/MS data. The top panel shows a fragment of a typical gas
chromatogram (GC) recording. The mass spectrum for the peak flagged on gas chromatogram is shown on the bottom
panel. The mass spectrum corresponds to a specific terpene compound called sabinene that is commonly found in citrus.
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COPYRIGHT © JANUARY 2012 ORO AGRI INC. • ALL RIGHTS RESERVED • TRANSFORMER AND LIQUID RIPPER ARE PROPRIETARY TRADEMARKS OF ORO AGRI
Celebrating Citrus
Farm Show concession for Boys & Girls Club
serves up a ‘citrus-y slaw’ and fresh-squeezed juice
Jim Gorden
C
abbage is an amazingly versatile
and healthy vegetable. The use
of cabbage in various forms is
common in many cultures of the world.
Here in the USA, one of its most common uses is in the quintessential American picnic green salad, coleslaw.
I enjoy its versatility and durability
for making green salads. I have hauled
it on 10-day mule pack trips into the
mountains of Baja California. There,
I prepared cabbage salads for the trip
participants and the cowboys/muleskinners of Baja who all enjoyed its
freshness after a long day in the saddle.
Interestingly, the cabbage maintained
its quality with only the cooling provided by a moist bean sack and in spite
of temperatures well into the 80s.
I have prepared my citrus-y slaw
for thousands of patrons of the Boys
and Girls Clubs food concession at the
World Ag Expo, aka “The Farm Show”,
held every February in Tulare, California.
At the inception of the food concession, we featured fresh navel orange juice. Now, we also offer a blend
of navel and blood orange juice as well
as fresh made lemonade. Many Farm
Show visitors were at first put off by
the blood orange juice, as it was new to
them. But after a few years of its becoming familiar, we find people coming
back and saying things such as “it’s really the Farm Show now as I’ve had my
glass of blood orange juice”.
About ten years ago, I started preparing coleslaw for the lunch plates
served at the concession. Initially, we
dressed the slaw with a rather traditional mayonnaise style dressing. I wanted
to offer something a little different,
featuring more citrus. Thus, I concocted
a Meyer lemon vinaigrette dressing,
which is a beautiful complement to the
cabbage. We make the dressing fresh
Bottom left: The B&GCS concession is famous for its special blend of navel and
blood orange juice. In the background are volunteers Emily Lowry and dad, Sonny.
Bottom right: She may be in charge, but there’s no getting out of dishwashing
duty for Mary Gorden. Photos by Chris Brooke.
each day with locally produced olive
oil and Meyer lemons.
The super citrus-y version of the
slaw includes diced orange, tangelo,
or mandarin tossed into the salad. The
citrus and cabbage complement each
other very nicely when prepared this
way. This salad may also be varied by
adding other ingredients to change its
character. Toss in a handfull of bacon
bits and a bit of hot curry into the vinaigrette for a hint of the Far East. Add
some chopped cilantro for a south-ofthe-border effect or a little chopped
fresh mint for a Moroccan touch.
For “feeding the masses” at the
Farm Show, we start each day with
at least 100 pounds of freshly shredded cabbage, two cups of finely grated
Meyer lemon zest, and three quarts of
vinaigrette.
But for a smaller crowd, like maybe
six, try the following:
Super citrus-y slaw for 6
• ½ head of cabbage, finely shredded
• Finely grated zest from a small to
medium size Meyer lemon
• Peel and dice an orange, tangelo
or mandarin
Meyer lemon vinaigrette dressing
• Combine in a small jar with a tight
lid, and shake to emulsify:
• 3 Tablespoons Meyer lemon juice
• 3 Tablespoons olive oil
• 1 Tablespoon sugar
• ½ Teaspoon salt
Combine the cabbage, zest and
diced citrus and toss with just enough
of the dressing to coat the cabbage.
Season to your taste with additional
salt and pepper, and enjoy.
Note that you can also use other
citrus zest in salads for a different effect. Minneola tangelo—or for that
matter almost any mandarin or orange—gives great flavor to salads. I
use a micro-plane grater to remove
the zest from a medium-size lemon
with a few easy strokes. You may
wish to adjust the acidity or sweetness of the vinaigrette, which you
can do by adding or reducing the
sugar proportion; or, if the Meyer
lemons are too sweet as they may
get toward spring, substitute some
regular lemon juice. Extra vinaigrette may be stored in the refrigerator for a week or more but will
need to warm up a bit before use as
the oil will solidify.
The backstory …
Based in Exeter, the Boys & Girls
Clubs of the Sequoias (B&GCS) serves
more than 7,000 kids a year at their afterschool programs at 17 sites throughout Tulare County. For their World Ag
Expo fundraiser, teams of volunteers
contribute more than 2,000 man-hours
of effort every year in staffing the concession, working from 6 a.m. to 6 p.m.
daily.
Gorden reports that his wife, Mary,
who serves on the B&GCS board of
directors, “carries the bulk of the load
for the overall planning and direction”
of the concession while he’s more involved with the food prep, which includes making the beans and the slaw
as well as overseeing the cooking of the
meat and the juicing operation. They
go through six bins of oranges, he says.
Lemon Cove grower Jim Gorden,
here with son Milo, is the immediate
past chairman of the Citrus Research
Board and continues to serve as an
active member of the Board.
CRB stakes out new territory
at World Ag Expo
A
fter years of occupying booth
space inside Pavilion A at the
World Ag Expo, the Citrus Research
Board moved to an outdoor space for
this year’s “Farm Show”, allowing the
program to expand the exhibit.
The new location is on a northsouth street just east of Pavilion B.
The number one advantage to the
outdoor space is that it’s large enough
to accommodate the mobile laboratory that Dr. Beth Grafton-Cardwell
and her team use in the field to train
members of the industry and the general public about management of citrus
pests. The microscopes inside the lab
provide close-ups of insect life stages.
Facing the mobile lab, on the opposite side of the “lot”, a tented area
housed a fresh fruit display, a demonstration of the CPDPP’s invasive pest
mapping website, and a demonstration
of the Nomad hand-held data loggers
used in the field in the Asian citrus
psyllid trapping program.
As for CRB’s former space in
Pavilion A, it’s now home to the CPDPP’s public education and outreach
program on ACP and huanglongbing.
...continued on next page
2012 World
Ag Expo
Continued from p. 59
Photo by Lynn Sanderson
Asian Citrus Psyllid Cooperative Project
California, Arizona, Baja California, and Sonora
United States
Department of Agriculture
SAN
BENITO CO
FRESNO CO
MONTEREY
CO
Animal and Plant
Health Inspection Service
INYO CO
TULARE CO
Navajo Co
KINGS CO
NV
Mohave Co
SAN LUIS
OBISPO CO
Coconino Co
KERN CO
Yavapai Co
SANTA
BARBARA CO
CA
LOS
ANGELES CO
VENTURA CO
Gila Co
SAN
BERNARDINO CO
San Miguel Santa Santa Anacapa
Island
Rosa Cruz Island
Island Island
San Nicolas
Island
La Paz Co
RIVERSIDE CO
Graham Co
Maricopa Co
Santa
Barbara
Island
Santa
Catalina ORANGE CO
Island
AZ
SAN
DIEGO CO
Pinal Co
IMPERIAL CO
San
Clemente
Island
Yuma Co
Pima Co
Legend
ACP_Regulatory Incidents_2011 thru Feb, 2012_CA & AZ
(
!
Asian Citrus Psyllid, CA_2012 thru 3-12-12 (4,302 records)
(
!
Asian Citrus Psyllid, CA_2011 (13,550 records)
!
(
(
!
Asian Citrus Pysllid, AZ_2011 (3 records)
(
!
Asian Citrus Psyllid, Mexico_2011 (614 records)
Santa
Cruz Co
Baja
California
Sonora
Asian Citrus Psyllid, Mexico_2012 thru 3-2-12 (82 recrods)
Quarantine for Asian Citrus Psyllid, CA (1/26/2012)
Quarantine for Asian Citrus Psyllid, AZ (12/7/2009)
USDA, APHIS, PPQ
GIS Specialist -- California
650 Capitol Mall, Suite 6-400
Sacramento, CA 95814
Coordinate-System:
CA Teale Albers, NAD 83
Date Printed: 3/15/2012
Time Printed: 07:47 hrs PT
Data Source:
CA Dept of Food & Agric.
AZ Dept of Agriculture
USDA, APHIS, IS
TeleAtlas Dynamap
o
0 10 20
40
60
80
The U.S. Department of Agriculture's Animal and Plant Health Inspection Service
collected the data displayed for internal agency purposes only. These data may
be used by others; however, they must be used for their original intended purpose.
Map of Asian citrus psyllid detections in California and neighboring portions of Arizona and Mexico through 3/12/12.
Miles
100
Please support the Harry Scott Smith
Biocontrol Scholarship Fund
at UC Riverside
A special message from
invasive species researcher Mark Hoddle
I
nvasive species are an ever-increasing problem in California agriculture, and
obviously citrus is no exception. One tool that can be used to combat invasive
species is biological control. The science of biological control – the use of a
pest’s natural enemies to suppress its populations to less damaging densities – was
pioneered in Southern California. This new discipline in entomology was in large
part driven by the citrus industry’s need to control invasive species, especially the
cottony cushion scale which was devastating citrus in the late 1880s.
The phrase “biological control” was first used by Harry Scott Smith in 1919 at
the meeting of Pacific Slope Branch of the American Association of Economic Professor Harry Scott Smith
Entomologists at the Mission Inn in downtown Riverside. In 1923, Smith, who
had been working on the biological control of gypsy moth with USDA, moved to
the University of California Riverside to form the Division of Beneficial Insect
Investigations, a unit separate and distinct from the Department of Entomology.
Prof. Smith, affectionately known as “Prof. Harry”, went on to create and
chair the Department of Biological Control at UCR, which offered the only
graduate degrees in biological control in the world. He is considered the “father”
of modern day biological control. Prof. Harry brought recognized entomological
training in biocontrol to California for the first time, encouraging work on the
applied and practical aspects. Under Prof. Harry’s supervision, the science of
biological control was developed in Southern California, and, naturally, a major
research focus was the biological control of citrus pests.
The Harry Scott Smith Biological Control Scholarship Fund in the Entomology
Department at UCR was started with a small gift from Prof. Harry, and regular
fundraising is necessary to maintain and grow the fund. The sole purpose of the
fund is to attract the brightest students to UCR to study biological control. To
do this, awards are made annually to provide assistance to students studying
biocontrol so they can attend conferences to present the results of their research
or to participate in training workshops.
With an ever-increasing number of production challenges facing the citrus
industry, biological control is still one of the best tools available for reducing
economic damage from invasive pests, and projects on Asian citrus psyllid and
Diaprepes root weevil are attempting to do this.
If you are interested in supporting the Harry Scott Smith Biological Control
Scholarship Fund at UCR, tax deductible donations made payable to the “UC
Foundation” can be mailed to Mark Hoddle, Department of Entomology, University of California, Riverside, CA 92521. More information on the Scholarship,
past awardees, and a list of donors can be reviewed at http://biocontrol.ucr.edu/
hoddle/harrysmithfund.html.
Any level of financial support you can provide for the Harry Scott Smith Mark Hoddle collecting Asian citrus psyllid
Biological Control Scholarship Fund at UCR will be greatly appreciated.
natural enemies in the Punjab of Pakistan.
Thank you,
Dr. Mark S. Hoddle
Director, Center for Invasive Species Research
UC Riverside
DPR honors Sunwest Fruit with
IPM Innovator Award
S
unwest Fruit Company, Parlier,
has been singled out by the California Department of Pesticide
Regulation as one of four organizations
receiving DPR’s 2011 IPM Innovator
Awards.
Ranch managers Greg Thonesen
and Brian Fien accepted the honor on
the company’s behalf at a Jan. 26 ceremony held at the Sacramento headquarters of the California Environmental Protection Agency. Sunwest
President Martin Britz was in attendance as was his son, Brett Britz.
The awards are presented annually
for leadership in reducing pesticide use.
Honored this year along with Sunwest
were the city of Palo Alto, Gallo’s Sonoma Vineyards, and Marin County.
Announcing the winners, DPR
noted that Sunwest, a privately owned
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grower/packer/shipper of stone fruit
and citrus, “uses a variety of innovative
IPM practices”.
DPR reported that the company
“grew the first citrus and stone fruit
certified by Protected Harvest, a nonprofit organization that promotes sustainable agricultural practices, and sold
under Zeal, an eco-label targeting socially and environmentally conscious
consumers.
“Sunwest has eliminated the use
of simazine, diuron and other herbicides known to contaminate ground
and surface water. It allows native vegetation to grow between trees, which
reduces erosion and soil compaction
and increases organic matter in the
soil. Other practices include modifying
tractors and adding enclosed cabs with
carbon air filters to reduce applicator
35-60 Horsepower Requirement
15-600 Gallon per Acre Capability
Maneuverable Ten ft. Long Chassis
Weight & Height Adjustment
Penetrating Spray from Twin Fans
Save 20-30% in Chemicals
Identical Spray Pattern Each Side
85% Droplets are 50 Micron Size
200-500 Gallon Tank
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
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
“Heavyweight Performance! Lightweight Price!”
exposure and provide a safer, more
comfortable work environment.
“The company traps and tracks
red scale populations with global positioning system mapping and partnered
with Agrian, a Fresno-based software
firm, to develop an iPad application to
Brian Fien and Greg Thonesen of Sunwest
Fruit Company. Photo by Alyssa Nichols,
courtesy of California Citrus Mutual.
capture the data. It uses pheromone
disruption for pests in stone fruit using dispensers known as puffers and
installed bio-filters in the Tivy Creek
watershed to filter runoff and prevent
pesticides and other pollutants from
entering the creek. “
DPR reports that since the IPM Innovator Awards were initiated in 1994,
more than 100 California organizations
have been recognized for their efforts
to reduce risks associated with pesticide use and for sharing their knowledge and methods with others. Nominees are evaluated in seven categories:
innovation, value, effectiveness, supports research, organizational education, outreach, and leadership. l
THE ANSWER
HELP WANTED
What happened in California 40 years ago that still impacts
pest management operations today (Do You Know, page 5)?
In the spring of 1972, the California Department of Agriculture
unveiled proposed regulations “that will place persons recommending agricultural pest control methods under strict licensing and registration requirements.”
As reported in the June 1972 issue of Citrograph, “The proposed
regulations set up procedures for licensing by the State Director of
Agriculture and registration with the agricultural commissioner of
every county in which the pest control advisers operate. To get an
agricultural pest control adviser’s license, the applicant must pass
a comprehensive test of his knowledge of laws, regulations, safety,
pests, pest control methods, and environmental effects of pesticides.
“Each agricultural pest control adviser will be required to place
all recommendations in writing and provide copies for the grower,
dealer, and applicator...”
Duarte Nursery is now hiring container growers specializing in citrus.
Salary commensurate with experience, all levels of formal education welcome to apply. For
more information, please contact Michael Vietti at (209)
531-0351 or [email protected].
Successful growers like
Mark Campbell of Willits &
Newcomb cover their Citrus
with Agra Tech Greenhouses.
Agra Tech is here to help
your crop stay healthy and
protected from Psyllids.
A FOLLOW-UP NOTE… In our grower profile
of John J. Gless (January/February 2012), we neglected to include something that obviously should have been mentioned
and that’s his work with California Citrus Mutual. He has
served on the CCM board of directors since 2003 and is an
active member of their marketing committee.
CITRUS
3LHGPRQW:D\3LWWVEXUJ&$
-LP%HUJDQW] 6DOHV(QJLQHHU
MLPEHUJDQW]#DJUDWHFKFRPZZZDJUDWHFKFRP
– AVOCADOS – OLIVES
Friends Day
May 4th 2012 • 9 am - 2 pm
• Tradeshow
• Tours
• Presentations
• Wine Tasting
• Lunch
For more information contact:
Sara at [email protected]
1555 Baldwin Rd.
Hughson, Ca. 95326
1 - 800 - GRAFTE D

IPM practitioner Joe Barcinas with IPM researcher Joseph Morse

Transcription

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