Alternative Weed Control Strategies Talk Overview · Alternative Weed Control Strategies Talk Overview • Why Manage Weeds? • Herbicide costs and beneﬁts • Integrated weed

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



Pepper Harvest in Saginaw MI (Brainard Lab, MSU).

Why Manage Weeds?

• Yield Loss



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


Direct Mortality: Cultivation

“Weed seedbank”


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.




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


Yr 1Results: Weed Coverage




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






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


Herbicides Applied


• 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


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


Manipulating competition: Cover Crops

“Weed seedbank”


Seed dispersal

Crop rotation: Downy brome in wheat

Blackshaw 1994

Seed production

Seed germination


Manipulating weed seed germination

“Weed seedbank”


Seed dispersal

“Stale seed bed”: stimulate germination and kill weeds BEFORE crop emergence

http://www.steamweeding.co.nz/information/index.html

Seed bed preparation

Stimulate weed seed germination

Kill weeds

Plant crop

Too deep for most weed emergence!


2. Cultural

4. Chemical

1. Mechanical

3. Biological

Weeds

Seed production

SeedGermination

Seed mortality

Seedlingmortality

Allelochemicals Seed predation Cover cropsMulch effectsNutrient effects

Seed decay

Davis & Liebman 2003

Red clover effects on weed seed predation “Many little hammers”

2. Cultural

4. Chemical

1. Mechanical

3. Biological

Weeds

• Citrus and other essential oils

• Citric/Acetic acid

• Some have crop restrictions

• All are contact post emergent herbicides

Organic HerbicidesClove Oil

Citric Acid

Thyme and Clove Oil

XPRESS0

2.5

5.0

7.5

10.0

Lev

el o

f W

eed

Con

trol

10

Hig

hes

t

Herbicide

Control RoundupAlldown Matran 2Xpress

Some key points

• Prevention is critical. Easier to avoid seed production than to promote seed predation and decay.

• Knowledge of the biology and ecology of weeds is useful for determining optimal management strategy

• Mechanical control (cultivation) has been foundation of alternative weed management, but has limitations.

• Cultural practices like crop rotation, planting density etc have great potential.

• “Many little hammers” necessary for successful management

MSU ResourcesIntegrated Weed Management: One Year’s Seeding

MSU ResourcesIntegrated Weed Management: Fine Tuning the System

MSU Resources: MSU Diagnostics

http://www.pestid.msu.edu/

Weed Management Talk Wed. 2/19/2014

Acknowledgements

• Krista Buehrer

• Brad Baughman

• Anne Nielsen

• Kristy Morrel

• Grower Collaborators

• Michigan Apple Committee

• US EPA PRIA2

• MSU Project GREEEN

} MSU OPM Lab

Documents

Alternative Weed Control Strategies Talk Overview · Alternative Weed Control Strategies Talk Overview • Why Manage Weeds? • Herbicide costs and beneﬁts • Integrated weed