Weed Control P drou l in Vegetable tiucon

Weed Controll in Vegetable
P duction
Produ
ti
• Richard Smith, Vegetab
ble Crop and Weed
S i
Science
Farm
F
Advisor,
Ad i
M t
Monterey
County
C
t
Why Care about Weeds
• Weeds are not microscopic
m
or
small like fungi and
a insects
• They can always
s be pulled out
• The issue is theiir impact
p
on crop
p
yield and on the economics of
farming
El Pellisco
Hours/Acre to Weed Carrots
Comparison of Orga
anic vs Conventional
Leaf Lettuce Prroduction Costs
System
Cos
sts
$/A
A
Percent of
Growing
C t
Costs
Organic1
257
7
8
Conventional2
132
32
5
1 – Tourte
T
and Smith, 2004; 2 – Tourte and Smith, 2001
Weed
W d Clas
Cl ssification
ifi ti
• Annuals
– Complete lifecycle
e in less than one year
(from seed to seed
d)
• Winter – germinate
e in fall and mature in early
spring
• Summer – May gerrminate in the fall or
spring, but mature in the summer
Winter annuals
Nettle
Groundsel
Shepherds Purse
Sow Thistle
Summer Annuals
Nightshades
Purslane
Nettleleaf Goosefoot
Weed Clas
ssification
• Biennial
– Live longer than on
ne year but less than
two. Often overwin
nter as a rosette and
resume growth in the
t spring
• Perennial
– Live more than one
e year. Can be woody
or fleshy. May have
e survive as tubers,
roots, nutlets, etc.
• Winter – active in th
he winter
• Summer – active in
n the summer
Soil Seed
d Bank
Nondormant
Dormant
Weed seed
d
Microbial
Physical
Physiological
Seed degradation
Germination
& Emergence
Tillage
& other
controls
Seed Death
D
Weed Strategie
es – Crop Areas
• Set Seed Quickly
– Groundsel, Burning Nettle
• Long
L
lived
li d seed
d
– Malva, Burr Clover
• Large
L
Numbers
N b
off Seed
S d
– Purslane & many others
• Set seed in surrounding areas
a
and invade from
the edges
– Groundsel,
Groundsel Sow thistle
Weed Contro
ol Strategies
•
•
•
•
Cultural
Mechanical
Ch i l
Chemical
Biological
– Few effective oth
her than seed
viability
i bilit declinin
d li ing in
i the
th soil
il over
time
Cultural Practice
es for Managing
Wee
eds
• Aggressively controlling weeds in all prior
rotations and during the fallow period over
the winter
eds going to seed
• Zero tolerance of wee
Cultural Practices
s to Reduce Weed
Press
sure
• Field selection
• Avoidance:
– Avoiding weedy fields
– Avoiding weediest
time of the growing
season (i.e. purslane
during
g June to Sept.)
p )
• PrePre-germination of
weeds
• Use of “stale”
seedbeds
• Planting vigorous
varieties on weediest
area
Effects of Preirrigation
No Preirrigation
With Preirrigation
• Reduces the number of weed seed that are ready
to g
germinate in the top
p la
ayer
y of the soil
• Can reduce weed emerg
gence in subsequent
crop by up to 50% (Shem Tov
To and Fennimore)
Stale Bed Technique: Pre-gerrminate and kill flush of weeds
on shaped beds
beds, priorr to planting cash crop
Mulching
Flaming
Cultivation
Liliston
Cultural Practices
s to Reduce Weed
Press
sure
• Control weeds that
aerial disperse from
surrounding areas
• Not letting weeds go
to
t seed
d
• Carrying weeds from
th fi
the
field
ld for
f disposal
di
l
elsewhere
•
•
•
•
•
•
•
•
Crop rotations
Deep
p plowing
p
g
Planting to moisture
p
Use of buried drip
irrigation
Solarization
Mulches
Transplants
a sp a ts
Cover crops
Weeds
Around
Edge of
Field
Source of weed infestation
Carry Weeds
O t off Fi
Out
Field
ld
Purslane in bags
carried to edge
e
of field
Planting to
Moisture
Buried Drip
Irrigation
g
Solarization
Solariz
zation
Colored mulches
Impact of Cover Crops on Weeds
Largest Chickweed Under 3 Co
over Crops at 2 Seeding Rates
(64 Days Aftter Planting)
Legume/Rye
Mustard
Rye
1x
Seeding
Rate
125 lb/acre
3x
Seeding
Rate
10 lb/acre
80 lb/acre
lb/
Use of Tra
ansplants
• Transplants
p
open
p op
pportunities
pp
p
for
mechanical weed control
• Transplants
p
give
g
the crop
p a head start on
the weeds
• Transplants
p
are more
e resistant to p
physical
y
manipulation
• Transplants
p
are easie
er for high
g tech
mechanical weeders to recognize
(distinguish from the
e weeds)
Mechanica
al Controls
• Cultivation
• Plowing
Sttandard
tandard cultivation with
Knives and sweeps
Cultivated Zone
Uncultivated
Zone 4” wide
Cultivated Zone –
80% of the bed
Typically 80+%
of a 40-inch
wide bed can
be effectively
cultivated The
cultivated.
fight with weeds
occurs in the
uncultivated
seedline
Precision Guidan
nce of Cultivators
Guided
G id d by
b the
h Operator
O
t
Effective but Slow
Old Technology
Modern Version
Camera Guidance
S t
Systems
for
f Cultivators
C lti t
4” wide cultivation strip
3” wide cultivation strip
Percent of Weed
ds Controlled at
Different Cultivattion Band Widths
2005 Lettuce
e Trial No. 1
Cultivation Ba
and Width
Hours Per Acre
A
to Weed
Different Cultivattion Band Widths
2005 Lettuce
e Trial No. 1
Cultivation Ba
and Width
Removal of W
Weeds from the
Seed
dline
• High Tech Ideas
Split Knife
D
Dave
Sl
Slaughter,
ht UCD
Lower Tech Ide
eas for Removing
Weeds from
m the Seedline
• In Europe where trransplanting of
vegetables is comm
monly used, there
is
i wider
id use off imp
i plements
l
t that
th t are
capable of removin
ng weeds from the
seedline
Finger Weeders
• This idea originally
g
y came from the US
– was invented by the Buddingh
Company Michiga
Company,
an
• The idea was take
en to Europe and
f h developed
further
d
l
d and
d refined
fi d (now
(
produced by three companies)
• The Europeans cla
aim their designs
can operate at high
her speed
Finger Weeders
W
Two sizes and two levels of hardness
14.5”
Softer
9.5”
Harderr
Kress Co, Germany
Torsion Weeder
F t Corp,
Frato
C
N th l d
Netherlands
Come in Differe
ent Sizes
7 & 9 mm
Transplanted Le
ettuce Trial No. 1
Percent Remo
oval of Weeds
Small Nettle Dominant Weed
100
90
80
70
60
50
40
30
20
10
0
Standard
14.5 orange
14.5 yellow
9.5 orange
9.5 yellow
Torsion 9mm
All cultivation treatments
Improved percent removal
Transplanted Lettuce Trial No. 1
Weeding Time
T
hrs/A
14
12
10
8
6
4
2
0
Standard
14.5 orange
14.5 yellow
9.5 orange
9.5 yellow
Torsion 9mm
Chemical Wee
ed Control for
Vegettables
• Herbicides are an im
mportant tool for
managing
g g weeds in vegetable
v g
production
p
• They greatly reduce the weed population
and make subsequen
nt hand weeding
operations more effic
cient
Types of Herbicides Used
• Preplant
– Fumigants
• Metam Sodium (Vapam
m)
– Burndown material used on beds jjust prior
p
to
planting
• Glyphosate (Roundup
p)
• Paraquat (Gramoxone
e)
• Carfentrazone (Shark))
Types of Herbicides Used
• Preemergence
– Applied prior to the emergence
e
of the weed
– Often applied at seed
ding with the crop
• Pronamide ((Kerb)) on lettuce
l
• Rimsulfuron (Matrix) on
o tomatoes
– Can be applied
pp
prior
p
to transplanting
p
g the crop
p
• Metolachlor (Dual Mag
gnum) on peppers
Types of Herbicides Used
• Postemergence
– Applied after the wee
eds have emerged in the
crop
• Applied as an selectiv
ve over
over--the
the--top application
– Halosulfuron (Sandea)) & rimsulfuron (Matrix) on
tomatoes
– Prometryn
y ((Caparol)
p
) on celery
y
– Oxyfluorfen (Goal) on onions
• Applied as a directed spray to the base of the plant
– Trifluralin
T ifl
li (Treflan)
(T fl ) on tomatoes
t
t
Goal 2XL
Goal Tender
e leaf
1st true
Sh h d Purse
Shepherds
P
1st true leaf
2nd true leaf
Goal Te
ender
Weed Burrn Down
U t t d
Untreated
G l Tender
Goal
T d 1st
1 t true
t
leaf
l f
Challenges for C
Chemical Weed
Control in Vegettable Production
• Fewer new herbicide
es being produced for
vegetables
g
• Loss of older herbiciide due to economic
or regulatory influences
Year of Registtration of Key
Vegetable Herbicides
Trade Name
Chemical
Representative Crop
Year Registered
Lorox
Linuron
Carrots
1966
Dual Magnum
S-metolachlor
Potato, Peppers
1976
Kerb
Pronamide
Lettuce
1972
Dacthal
DCPA
Broccoli, Onions
1958
Devrinol
Napropamide
Broccoli, Tomatoes
1972
Caparol
Prometryn
Celery
1964
Why few new
w herbicides?
Roundup
p Ready
y Corn
C
and Soybeans
y
Why few new
w herbicides?
Resistant weeds may change the situation
New Use for Old
O Herbicides
•
•
•
•
Lorox on Spinach
Goal on Broccoli and
d Onions
Prowl H2O on transp
planted lettuce
C
Caparol
l on C
Carrots
t
Summ
mary
• Weed control in vege
etables is
accomplished
p
by
y a combination
c
of
strategies: Cultural, Mechanical and
Chemical
• Effective use of all th
hese tools assists
growers in achieving
g economical weed
control