3. Botryosphaeria_Michailides - Cooperative Extension Contra Costa

Understanding and Managing Walnut
Botryosphaeria/Phomopsis Canker and Blights
(Influence of El Niño on the Sleeping Giant)
Themis J. Michailides
D. Morgan, J. Moral, D. Felts, R. Puckett, M. Luna
U N IVE RS ITY OF CALI FO R N IA
Kearney Agricultural Research and Extension Center &
University of California Cooperative Extension
Quad-County Walnut Institute, Stockton – 15 March 2016
Cooperators: J. Hasey, R. Buchner, B. Coates, K. Pope, K. Anderson, J. Grant,
and D. Lightle: UCCE Sutter/Yuba/Colusa, Tehama, San Benito, Yolo/Solano, Stanislaus, San
Joaquin, and Butte/Glenn counties, respectively
El Niño winters in California (1982 through 2015)
Winter 1982-1983 “El Niño storms”
Winter 1994-1995 “winter storms”
Winter 1997-1998 “El Niño storms”
The Bot disease started in 1983, probably in the oldest
pistachio orchard in the State (Butte Co., CA)
El Niño winters in California (1982 through 2015)
Winter 1982-1983 “El Niño storms”
Winter 1994-1995 “winter storms”
Winter 1997-1998 “El Niño storms”
1995
El Niño winters in California (1982 through 2015)
Winter 1982-1983 “El Niño storms”
Winter 1994-1995 “winter storms”
Winter 1997-1998 “El Niño storms”
Bot epidemic of 1998
… because of Botryosphaeria blight
Winter 2015-2016 “El Niño?
Botryosphaeria /Phomopsis of walnuts in Spain
Symptoms we expect to see in walnut orchards
in an El Niño year in California
Latent infection of fruit:
Blighted fruit and pathogen isolation from kernels of walnut fruit
inoculated with Lasiodiplodia citricola
120.0
Lasiodiplodia citricola
Infection (%)
Brighted fruit
100.0
80.0
Isolation from kernel
a
ab
abc
bc
Blighted fruit
abc
bc
60.0
A
c
A
40.0
20.0
A
AB
B
B
B
B
infected kernels
0.0
%
5/12 5/22 6/1 6/11 6/21 7/1 7/11 7/21 7/31 8/10 8/20 8/30 9/9
May
120.0
Sept.
B
Neofusicoccum parvum
blighted fruit
a
100.0
Isolation from kernel
bc
80.0
c
c
c
bc
ab
Infection of intact fruit in the orchard
All Botryosphaeria
& Phomopsis
species
Fruit
Fruit
Peduncle
Infect spurs/shoots
Spurs with cankers covered
with sporulation (pycnidia)
Susceptible walnut cultivars
Ashley
Chandler
Howard
Tulare
Vina
Serr
Hartley
Payne
Dixon
Livermore
Botryosphaeriaceae
Phomopsis
Distribution of
“Botryosphaeria” spp.
in walnut orchards
N. mediterraneum =
widespread
Botryosphaeria dothidea
Neofusicoccum spp.
Diplodia seriata
Lasiodiplodia spp.
Neoscytalidium**
Perithecia
Pycnidia
Oozing pycnidia of Botryosphaeria on walnut spurs
water
water
0
Rain:
Oozing pycnidia
The majority of spores will be
released within 30 minutes
Spores of Botryosphaeria
they germinate within 1.5 hours wetness!
Germination under adverse (wet/dry/wet)
conditions and surviving mechanisms
Botryosphaeria spread
 rain & moving water in the orchard +++++++*
 air (airborne ascospores)
++
 pruning equipment
 insects
*rain, dew, sprinkler irrigation
+
?
Conditions for infection events
 Presence of inoculum
 Rain: at least 1/4”
 Temperature: ≥ 50°F
 Presence of susceptible tissues
Cankers associated with pruning wounds
Average canker length (cm)
Susceptibility of pruning wounds of 1-, 2-, 3-, & 416 year-old wood to infection by Bot
14
a
ab
12
abc
10
bcd
abc
bcd
8
cd
cde
6
de
4
a
e
b
b
2
Post-pruning inoculation date
16 w
eek
8 we
ek
4 we
ek
3 we
ek
2 we
ek
1 we
ek
12 w
eek
Pruning on 9 & 10 Feb 2015
3 day
0 day
contr
ol
0
Prune branch
Walnut branch
Walnut branches
Average canker length (cm)
Susceptibility of pruning wounds to infection by Bot
as affected by age
16
Pruning on 9 & 10 February 2015
14
a
5-6 inches
a
12
10
8
6
4
up to 2 inches
b
b
2
0
1 year
2 year
3 year
4 year
Age of inoculated shoots
Treatment of pruning wounds with fungicides and
then inoculation with Neofusicoccum parvum
10
Neofusicoccum parvum
8
ab
6
ab
b
4
b
2
Meri
vo
A bou
nd
n+Vi
tiS
eal
n
Meri
vo
Quad
ris
Top
0
Cont
rol
Average canker length (cm)
a
Wounds in the field during 1) the season,
2) at harvest and 3) postharvest
Leaf scars
*
Peduncle
scars
*
Canker
*
Fruit scars when walnuts drop
Infection Courts of Botryosphaeria and Phomopsis
During the season:
At harvest:
 Wounds from hail, freeze,
sunburn, wood peckers

 Pruning wounds
Scars from peduncles
 Fruit wcars
Postharvest:
 Leaf scars
 Scalewounds
Peduncle scars
 Mechanical wounds
 Walnut
lesions
 blight
Leaf scars
 Husks (remaining on the tree)
 Pruning wounds
 Wounds from freeze damage
 Injuries from wood peckers
 Other type of injuries
Leaf scar infections
Injuries (wounds) by walnut scale & Botryosphaeria
walnut scale
Injuries from scales
Necrotic lesions
More than 50% of necrotic
lesions had Botryosphaeria spp.!
Management of Botryosphaeria canker
and shoot blight:
 1. Assessment of Bot inoculum risk:
BUDMON, or CANCERED SPURS (… in progress).
 2. Cultural control: Sanitation: prune infected
shoots to remove cankers and reduce spore inoculum;
avoid wetting the tree canopy.
 3. Chemical control: Apply fungicide sprays.
Best control…
 Integrated disease control: Use all of the above
(1 + 2 + 3).
BUD MONitoring (= BUDMON) Technique
BOT
BOT
Bud collection:
February/March
Results in 6-7 days
% of buds with Bot
Sanitation by pruning
Walnut prunings
Presence of pycnidia with viable
Viability
%spores
Bot survival in chipped wood
120
100
80
60
40
20
0
Unchipped
Chipped
c/o Katherine Pope, UCCE Yolo /Solano
Botryosphaeria …………. 40%
Phomopsis ……………….. 30%
Botryosphaeria + Phom.…. 20%
No pycnidia……………..…..10%
90%
Compost
Botryosphaeria ……..…0%
Phomopsis …………….. 0%
Botryosphaeria + Phom.. 0%
Effects
of fungicides
on Botryosphaeria
Chandler
Montgomery
fungicide
efficacy 2014 in
seasons
walnut shoots/spurs
(Butte Co.) - 2014
– all treatments
SPRAYS: May 8, June 12, and July 10
a 4X
a
a
a
a
ab
ab
ab
ab
ab
ab
ab
ab
ab
ab
ab
Merivon
Quash
Ph-D + Tebucon
K Phite
Fontelis + OR009
K Phite + Latron
EXP 1 + EXP 3
EXP1 + EXP 2
Luna Sensation 7.6 oz
EXP 1
Pristine
Luna Experience 10 oz
Fontelis + Tebucon
Luna Experience 6 oz
Badge + Manzate
Ph-D
Fontelis
Quadris Top
Viathon
Luna Sensation 5 oz
Control
0
2
4
abc
abc
abc
6
bc
8
Blighted
Blightedshoots
spurs (%)
(%)
c
10
12
14
Nuts at harvest
No discoloration
Brown kernels
Isolations on agar media
Black kernels
Expe
rienc
e
rol
Cont
a
8
Blackkernels
kernels
Black
6
4
ab
2
0
ab
ab
b
b
b
b
Botryosphaeria spp. (%)
10
b
0
Cont
rol
Luna
Expe
rienc
e (1)
Luna
Expe
rienc
e (2)
Quad
ris T
op (1
)
Quad
ris T
op (2
)
Meriv
on (1
)
Meriv
on (2
Font
)
elis+
Tebu
con (
1)
Font
elis+
Tebu
con (
2)
Luna
(1)
Expe
rienc
e (2)
Quad
ris T
op (1
)
Quad
ris T
op (2
)
Meriv
on (1
)
Meriv
on (2
Font
)
elis+
Tebu
con (
1)
Font
elis+
Tebu
con (
2)
Luna
Botrysphaeria spp. (%)
Effects of fungicides on Botryosphaeria in Chandler
walnut (black and brown kernels) (Colusa Co.) - 2014
8
a
Brown
kernels
Brown kernels
6
4
2
ab
ab
b
ab
ab
ab
b
b
Efficacy of four calendar sprays of fungicides in a Chandler
walnut orchard in Butte Co. (Sacramento River) - 2015
SPRAYS: May 12, Jun 11, Jul 10, Aug (4X SPRAYS)
Pristine
Ph D + Tebuconazol
Fontelis + Abound
Font-Teb>QuadTop>Font-Teb>QuadTop
Indar
Fontelis + Vintre
Luna Experience
Viathon
Quadris Top
Fontelis + Tebuconazol
Quash
Luna Sensation
Ph D
Badge-Manzate Pro Stick
Fracture
Merivon
Fontelis
Control
a
ab
ab
ab
ab
ab
abc
abc
abc
abcd
a
abcd
abcd
abcd
abcd
bcd
bcd
bcd
cd
d
0
1
2
3
4
5
6
Blighted spurs (%)
7
8
9
Leaf wetness model (LWM) where rain exceeded
threshold in a Chandler walnut orchard in Butte
County
Leaf wetness, hours
60
sprayed
50
April 8-9 (8 mm)
40
High Risk
sprayed
April 24-25 (18 mm)
sprayed
30
Sept. 16-17 (3 mm)
20
Medium Risk
10
Low Risk
0
5
10
15
Temperature, °C
20
25
Various timings of Merivon® fungicide in a Chandler
walnut orchard in Butte Co. - 2015
Merivon: bloom, May, June, July
Bloom + Standard calendar
a
Merivon: April 9, 26; Sept 17--leaf wet
Leaf wetness model
ab
Merivon: May, June, July, post-harvest
4X
3X
Standard calendar+postharvest 4X
bcd 1X
abc
Merivon: post-harvest
Merivon: May, June, July
Standard calendar 3X
cde
Merivon: bloom, May, June, July, post-harvest
cde
5X ?
Merivon: bloom, post-harvest
cde
2X
Merivon: bloom
de
1X
Control
e
0
SPRAYS:
Calendar: May 12; Jun 12; Jul 10 = 3X
1
2
3
4
5
6
7
8
9
Blighted spurs (%)
Bloom: Apr 9 = 1X; Postharvest: Nov 3 = 1X
Best-timing of a single spray of Merivon® in a
Chandler orchard in Butte Co. - 2015
5.0
ab Bloom
Blighted spurs (%)
4.5
4.0
ab
3.5
Postharvest (PH)
ab
Best
timing
ab
a
3.0
Nonsprayed = 8%
2.5
2.0
a
1.5
Meriv
on: p
ost: h
a
rvest
gust
Meriv
on: A
u
Meriv
on: J
uly
Meriv
on: J
une
n: Ma
y
Meriv
o
Meriv
on: b
loom
1.0
SPRAYS: Apr 9 (bloom); May 12; Jun 12; Jul 10;
Aug 10; Nov 3 (PH)
www.ipm.ucdavis.edu
Efficacy of registered fungicides against Botryosphaeria
canker and blight of walnut
Fungicide
Active ingredient
Efficacy
Quash…………
Merivon…….…
Pristine ……….
Quadris Top…..
Switch…………
PhD…..……….
Viathon………..
K-Phite ……….
Luna Experience
Luna Sensation
Fontelis
Manzate
metconazole
++++
fluxopyroxad+pyraclostrobin ++++
boscalid + pyraclostrobin
+++
difenoconazole + azoxystrobin+++
cyprodinil + fludioxonil
++++
Polyoxin-D
+++
tebuconazole + phosphite
+++
Polyphosphite
++++
fluopyram + tebuconazole
+++
fluopyram + trifloxystrobin
++
penthiopyrad
+++
copper-mancozeb
++
Efficacy: + = poor: ++++ = excellent
http://www.ipm.ucdavis.edu
Scenarios for sanitation & sprays
 Orchards - Heavy infection (>50%): Prunings need to be chipped and they may be
left in the orchard; apply 3-5 fungicide sprays ((bloom, May, Jun, July, and postharvest).
 Orchards - Moderate infection (21% - 50%): Prune or hedge these orchards first
and then move into heavily infected orchards; prunings need to be moved out of the
orchard; at least 3 sprays (bloom and June spray, & July – depending on weather
conditions).
 Orchards – Light infection (6% - 20%):
Prune or hedge these orchards first and then move into more infected orchards;
prunings need to be moved out of the orchard; two sprays (bloom and mid June to early
July).
 Orchards – Very light infection (1% - 5%): Prune infections and destroy them out
of the orchard; no spray(s) needed, unless it rains.
 Orchards – No infection: no Botryosphaeria yet (0%): Prunings can be chipped
and left in the orchard; no spray(s) are needed.
CONLCUSIONS
 For best management we need all: a) assessment of
inoculum risk; b) sanitation; and c) fungicide sprays.
 Sprays during May through July/August reduce
Botryosphaeria (confirmed in 2014 & 2015).
 Bloom sprays and postharvest sprays seem to reduce
disease (we need to repeat in 2016).
 Sprays after a rain/infection event seem to be very effective
(we need to repeat in 2016).
 The best-timing spray seems to be around mid-June to
early/mid July (we need to repeat in 2016).
Acknowledgments
UC Kearney Agricultural
Research & Extension
Center
David Morgan
Dan Felts
Yong Luo
Ryan Puckett
Juan Moral
& farm advisors
Thank you
Percentage of walnut branches infected
Effect of walnut scales on infection of walnut
by Botryosphaeriaceae (cv. Vina)
20%
18%
Shoots w/
scales
a
16%
Inoculation
Without wounding – spore suspension
Shoots w/
scales
14%
Shoots w/
scales
a
12%
a
10%
8%
6%
W ith s c ales
No s c ale
b
b
b
4%
2%
0%
L as iodiplodia
c itric ola
Neofus ic oc c um
parvum
Neofus ic oc c um
mediterraneum
C ontrol
Treatment
60-75% more shoots were infected when scales were
3 weeks after inoculation
present than when scales were not present