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YOUTH & FAMILIES AGRICULTURE HEALTH ECONOMY ENVIRONMENT ENERGY COMMUNITIES
Cheatgrass Control in Winter Wheat;
What Works
Aaron Esser
WSU Extension Agronomist,
Lincoln-Adams Area
210 W Broadway
Ritzville, WA 99169
(509) 659-3210
Ritzville Chemical Grower Meeting Ritzville, WA. February 27, 2008
Welcome
http://lincoln-adams.wsu.edu
agriculture
http://lincoln-adams.wsu.edu
agriculture
Maverick applied to Group 2 SUSCEPTIBLE downy brome
Maverick applied to Group 2 RESISTANT downy brome
Trends
• Higher Wheat Prices
– Higher input costs • Herbicides
– Greater return to herbicide input • Weeds losses cost more
– Crop injury greater cost
– Herbicide persistence greater cost
– Integrated management still provides best sustainable return
Yenish, et al.
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agriculture
Focus, “back to the basics”
• Cheatgrass Ecology – Root and plant development
– Seed production
– Yield reduction
• Cultural control with the
goal of improving
herbicide efficacy – A number game
– Residue mgt
– Herbicide efficacy, herbicide
resistance mgt
http://lincoln-adams.wsu.edu
agriculture
Life with Group 2 Herbicides [Acetolactate synthase (ALS) inhibitors]
Diesel
$3.00/gal
Glyphosate
$20.00/gal
Maverick Olympus Olympus Flex Osprey Beyond
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agriculture
Life BEFORE Group 2 Herbicides
Diesel
$0.75/gal
Glyphosate
$100.00/gal
Lexone Fargo Sencor
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agriculture
Life BEFORE & WITH Group 2 Herbicides
http://lincoln-adams.wsu.edu
agriculture
Cheatgrass Ecology
• Downy Brome (Bromus
tectorum L.)
– aka cheatgrass
– Winter-annual grass
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agriculture
Cheatgrass Ecology
• Downy Brome (Bromus
tectorum L.)
– Germinates primarily
in the fall
– Root system grows
throughout at soil
temperatures just
above freezing
0- 15”
3’- 4’
90%
370 F
H2O NH4
wheat cheat
http://lincoln-adams.wsu.edu
agriculture
Cheatgrass Ecology
• Downy Brome (Bromus
tectorum L.)
– Seed can be produced
from spring germinating
plants
– Seed production is more
prolific on fall germinating
plants
– Rapid development from
heading to seed make it
difficult to prevent seed
production
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agriculture
• Downey Brome Seed Production
– Dense infestation = 500# Seed/ac (250,000 in 1 #)
– 400 seeds per plant
– Require short after-ripening period
• Little dormancy remains
– Seed germination often exceeds 95% for seed
buried within 2 inches of the soil surface
– Viable in soil for 2 to 3 years
Cheatgrass Ecology
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agriculture
• Losses due to downy brome infestations vary
widely.
• Research in the PNW has shown moderate
infestation emerging within 10 days of wheat
emergence can reduce winter wheat yields by
around 1/3
Cheatgrass Ecology: Wheat Yield Loss
Source: PNW 0509, Managing Downy Brome Under Conservation Tillage Systems in the Inland Northwest
Cropping Region.
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agriculture
Cheatgrass Ecology: Wheat Yield Loss
Percentage winter wheat yield loss due to downy brome emerging 0 to 14 and 21 to
35 days after winter wheat. (P.W. Stahlman and S.D. Miller, 1990. Weed Science
38:224-228)
0
5
10
15
20
25
30
0 20 40 60 80 100
Downy Brome Population (plants /sq. yd)
Wh
eat
Yie
ld L
oss (
%)
Dow ny Brome emergence 0-14 days after w heat
Dow ny Brome emergence 21-35 days after w heat
Source: PNW 0509, Managing Downy Brome Under Conservation Tillage Systems in the Inland Northwest
Cropping Region.
http://lincoln-adams.wsu.edu
agriculture
0
20
40
60
80
100
0 20 40 60 80 100
Downy Brome Population (plants /sq. yd)
Va
lue
of
Wh
ea
t L
os
s (
$/a
c)
Downy Brome emergence 0-14 days after wheat
Downy Brome emergence 21-35 days after wheat
50 bu/acre wheat@ $8.00/bu
Cheatgrass Ecology: Wheat Value Loss
http://lincoln-adams.wsu.edu
agriculture
Cultural control with the goal of improving herbicide efficacy
http://lincoln-adams.wsu.edu
agriculture
A number’s game: Culture control to improve herbicide efficacy
3’
3’ 3’
3’
100 plants/yd2 20 plants/yd2
http://lincoln-adams.wsu.edu
agriculture
A number’s game: Culture control to improve herbicide efficacy
3’
3’
3’
3’
90% control with herbicide application
10 plants/yd2 2 plants/yd2 4,000 seeds 800 seeds
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agriculture
