Matt Grieshop 1 , Daniel Brainard 2 , Erin Haramoto 2 1 MSU Entomology 2 MSU Horticulture Michigan State University Alternative Weed Control Strategies Talk Overview • Why Manage Weeds? • Herbicide costs and benefits • Integrated weed management • Weed management tactics • Weed management resources at MSU Why Manage Weeds? • Yield Loss • Harvest Interference • Pest Interactions Estimates of average crop yield losses due to weeds range from 12-25% (Pimentel et al 2000; Parker and Fryer 1975). Organic asparagus—Oceana County, MI Why Manage Weeds? • Yield Loss • Harvest Interference • Pest Interactions Pepper Harvest in Saginaw MI (Brainard Lab, MSU). Why Manage Weeds? • Yield Loss • Harvest Interference • Pest Interactions Meadow Voles girdling dwarf trees Herbicide Use >60% Total Applied Pesticides!!!
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Alternative Weed Control Strategies Talk Overview · Alternative Weed Control Strategies Talk Overview • Why Manage Weeds? • Herbicide costs and benefits • Integrated weed
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Transcript
Matt Grieshop1, Daniel Brainard2, Erin Haramoto2
1MSU Entomology2MSU Horticulture
Michigan State University
Alternative Weed Control Strategies Talk Overview• Why Manage Weeds?
• Herbicide costs and benefits
• Integrated weed management
• Weed management tactics
• Weed management resources at MSU
Why Manage Weeds?
• Yield Loss
• Harvest Interference
• Pest Interactions
Estimates of average crop yield losses due to weeds range from 12-25% (Pimentel et al 2000; Parker and Fryer 1975).
Organic asparagus—Oceana County, MI
Why Manage Weeds?
• Yield Loss
• Harvest Interference
• Pest Interactions
Pepper Harvest in Saginaw MI (Brainard Lab, MSU).
Why Manage Weeds?
• Yield Loss
• Harvest Interference
• Pest Interactions
Meadow Voles girdling dwarf trees
Herbicide Use
>60% Total Applied Pesticides!!!
Herbicide Costs and Benefits
• Can be Cheap!
• Low Labor!
• Broad Spectrum!
• Can be expensive
• Crop Damage
• Human Health Risk
• Resistance Susceptible
Pros Cons
Herbicide Crop Damage
• Overspray: Roundup on apples
• Drift: Dicamba on tomatoes http://www.omafra.gov.on.ca
http://extension.missouri.edu/
Herbicide Resistance Integrated Weed Management
• Apply knowledge of pest life cycles to identify and target weak points
• Prevention better than treatment
• “Many little hammers”: Use multiple tactics to maximize effectiveness and minimize risks
Seed production
Seed germination
Establishmentand growth
Annual weed life cycle
“Weed seedbank”
EmergenceSeed burial
Seed dispersal
0
50
100
150
200
250
300
350
0 1 2 3 4 5 6 7 8 9 10
Years after seed input
Em
erg
ence
(se
edli
ng
s/m
2)
05,00010,00030,00060,000
Future costs of seed production
Seed input
(seeds/m2)
Brainard 2002
“One year’s seeding, seven years weeding”
Pig
wee
d
“Many little hammers”
2. Cultural
4. Chemical
1. Mechanical
3. Biological
Weeds
Rotary Hoe Inter-row cultivation
Mechanical/Physical: Cultivation
Seed production
Seed germination
Establishmentand growth
Direct Mortality: Cultivation
“Weed seedbank”
EmergenceSeed burial
Seed dispersal
Methods: Preliminary Exp.
• Sites cultivated once per month May-August
• Sparta and Flushing sites cultivated with a Wonder Weeder implement
• Potterville site cultivated with a grower built implement
• Monthly weed measurements on 3 rows cultivated & 3 rows grower standard practice
• Also collected soil samples in June and August, leaf nutrient samples in June, mite counts in July and terminal growth of trees
“Wonder Weeder” Yr 1Results: Weed Coverage
• Cultivation greatly reduced ground cover compared to no treatment
• Cultivation was comparable to burn down herbicides
• Pre-emergent herbicides had less ground cover
0
20
40
60
80
100
05/12/10 05/28/10 06/10/10 08/06/10 09/06/10
% B
are
Gro
und
Flushing Cult. Flushing No Cult. Potter. Cult. Potter No. Cult.Sparta Cult. Sparta No Cult.
• Cultivation greatly reduced ground cover compared to no treatment
• Cultivation was comparable to burn down herbicides
• Pre-emergent herbicides had less ground cover
0
20
40
60
80
100
05/12/10 05/28/10 06/10/10 08/06/10 09/06/10
% B
are
Gro
und
Flushing Cult. Flushing No Cult. Potter. Cult. Potter No. Cult.Sparta Cult. Sparta No Cult.
Yr 1Results: Weed Coverage
• Cultivation greatly reduced ground cover compared to no treatment
• Cultivation was comparable to burn down herbicides
• Pre-emergent herbicides had less ground cover
0
20
40
60
80
100
05/12/10 05/28/10 06/10/10 08/06/10 09/06/10
% B
are
Gro
und
Flushing Cult. Flushing No Cult. Potter. Cult. Potter No. Cult.Sparta Cult. Sparta No Cult.
Yr 1Results: Weed Coverage
• Cultivation greatly reduced ground cover compared to no treatment
• Cultivation was comparable to burn down herbicides
• Pre-emergent herbicides had less ground cover
0
20
40
60
80
100
05/12/10 05/28/10 06/10/10 08/06/10 09/06/10
% B
are
Gro
und
Flushing Cult. Flushing No Cult. Potter. Cult. Potter No. Cult.Sparta Cult. Sparta No Cult.
Herbicides Applied
Yr 1Results: Weed Coverage
• Biomass significantly reduced compared to no herbicides
• Biomass comparable to herbicide treatments
0
0.2
0.4
0.6
0.8
1.0
Flushing Pottersville Sparta
Dry
Bio
mas
s o
z.
CultivatedNot-Cultivated*
Cult.vs Untreated
Yr 1Results: Weed Biomass
Cult.vs. Herbicides
“Many little hammers”
2. Cultural
4. Chemical
1. Mechanical
3. Biological
Weeds
• Select competitive resistant varieties
• Provide optimal growing conditions
• Irrigate and fertilize crop, not weeds
• Transplant to give crop head-start
• Increase planting density and planting uniformity
Cultural Weed Control
Seed production
Seed germination
Establishmentand growth
Manipulating competition: Cover Crops
“Weed seedbank”
EmergenceSeed burial
Seed dispersal
Crop rotation: Downy brome in wheat
Blackshaw 1994
Seed production
Seed germination
Establishmentand growth
Manipulating weed seed germination
“Weed seedbank”
EmergenceSeed burial
Seed dispersal
“Stale seed bed”: stimulate germination and kill weeds BEFORE crop emergence