Organic weed management: proven and new approaches

Organic weed management in field crops Proven and new approaches

Dr. Joel Gruver Western Illinois University

j-gruver@wiu.edu

PRECISION

Currently only available upon request Will soon be downloadable

from our website

http://www.wiu.edu/cbt/agriculture/farms/organic/

High tech precision vs. attention to detail

In 2012, I witnessed a new level of attention to detail

Why is there rapeseed on the edge of this bean field?

Prior to working with Gary, I was under the impression that cultivation had limited ability to control in-row weeds and

wondered if in-row cover crops might be of value

Steel in the Field shows how today's implements and

techniques can control weeds while reducing—or

eliminating—herbicides.

In practical language, Steel in the Field presents what

farmers and researchers have learned in the last 20 years about cutting weed-control

costs through improved cultivation tools, cover crops and new cropping rotations.

Row crop farmer profiles

STEEL in the FIELD

Dryland farmer profiles

The shovels leave soil roughly ridged with some incorporation of residue. The pass exposes roots of fall

growing weeds such as quackgrass and field bindweed to winter’s wrath. He makes a second fall pass if weeds begin to

regrow, or if quackgrass is a problem.

Weed control, however, starts in October. “The last cultivation in fall is our first weed management for

spring,” Jacobson says. He uses 4- inch beavertail shovels (pointed at the bottom, wide at the top) on his chisel plow.

To stimulate weed growth, he harrows in late April as soon as soil dries out.

His Herman stiff-tine harrow has round tines about 5/16ths of an inch in diameter..

He controls the subsequent weed flush with a field cultivator outfitted with 9-inch sweeps. He makes a second pass if weed pressure is heavy and if he can

delay planting.

Terry uses a Seed-Right hoe drill

Crop Rotation on Organic Farms: A Planning Manual provides an

in-depth review of the applications of crop rotation-including

improving soil quality and health, and managing pests, diseases, and

weeds. Consulting with expert organic farmers, the authors share

rotation strategies that can be applied under various field

conditions and with a wide range of crops.

Crop Rotation on Organic Farms is most applicable to farms in the Northeastern United States and

Eastern Canada but is worth a look

3 broad goals of ecological

management

Activation

Augmentation Conservation

Suppression

A nice flush of weeds ready for termination

What can we do to maximize this flush?

Not all tillage operations have the same effect

Terminating spring planted oats with a soil finisher ~ 3 weeks before planting corn

GOAL = biological activation and weed suppression

Planting into poorly digested red clover residues

Corn seed was planted into moisture but ~ 25% of one hybrid and > 50% of another

was lost to seed rot and insect feeding

We had near perfect stands in every other field

Are you familiar with the fence post principle?

Zone of maximum biological activity and rapid residue decay

Deeper burial does not optimize decay but sends weed seeds into deep dormancy and brings deeply dormant

weed seeds to the surface where they germinate slowly

Who is sleeping in your soils?

Do any of you have experience with flame weeding?

Dennis Leutke in MN and Larry Shrock in MO are experts

Terminating weeds without awakening sleeping seeds

Cropping system strategies vs.

Direct control strategies

Effective strategies disrupt weed life cycles

Cropping system strategies

Crop rotation Tillage rotation Cover cropping

Crop management Fertility management Manure management

Field/equipment/seed sanitation

Optimizing crop growth to maximize crop competitiveness

-Select a well adapted variety (maximum leafiness and rate of canopy closure) -Delay field work (soil must be warm enough for rapid crop emergence) -Prepare a good seed bed (start out clean) -Reduce row spacing and increase populations -Row fertilizer?

Preventive management

• Flush soil seed bank with fallow periods

• Walk crops

• Employ alternative equipment for mowing, pulling weeds

• Weedy crops -> forage or cover crops

Hopefully it doesn’t really take 15 years for preventative management to pay

Well established fall planted small grains are very competitive

against weeds

Do you see a cover crop?

Do you see a cover crop?

Frost seeded clover

the most tried and true cover cropping system in the Midwest region

Sweet clover

Mustard

Frost seeding options

Klaas and Mary Martens, organic innovators in Central

NY State, are reporting excellent results with frost-

seeded confectionary mustard ahead of dry beans

Preceded by radish :-<

Results would probably be opposite during a normal or wet year

Where are the soybeans??

Traditional organic weed management often comes up short during wet years

A strong stand of cereal rye was incorporated ~ 2 weeks before these soybeans were planted

Pioneering work by Jeff Moyer at the

Rodale Institute

has sparked considerable interest

in organic no-till across the country

Innovation all across the US

Innovative farmers have built lots of

interesting looking rollers

Some times its best to make do with what you already have

Cultimulcher Front mounted Rodale roller

October 2008

Cereal rye drilled at 60 lbs/a in late August

Our experience is that a strong stand of rye is much more important than roller design

Early June 2009

1 week later

~2 weeks after planting

July

August late September

Early November 2009

No-till, bio-strip-till and conventional till plot averages ranged from 51.6 to 58.6 bu/ac

No significant differences between systems

We planned a ridge-till vs. no-till comparison for 2010

May 2010

July 2010

We drilled into standing rye without rolling on 6/7 because of a very narrow window between rains.

We ended up knocking down the ridges and were not able to plant these plots until 7/4 due to excessive wetness

November 2010

Plot yields ranged from 42-52 bu/ac

Significant foxtail pressure but almost no broadleaf weeds

June 2011

August 2011

November 2011

The NT bean plots yielded ~10 bu more than the best

tillage system plots

April 2012

Planting into 5-6’ tall rye on May 11

Double drilled with 4” offset

June 2012

Our 2012 NT bean yields ranged from ~ 30 to ~ 60 bu/a

60-70 bu/a

In July 2012, we undercut several fields of small grain stubble using a Hinniker no-till cultivator and a tractor with RTK guidance

Fallow strip Cover crop cocktail no-till drilled after

undercutting

Triple S mix Sunflowers, Soybeans & Sunn hemp

We started growing sunflowers in 2010 when >300% of normal precip in May, June and July kept us out of

the fields planned for corn

July 17 planting

We could hardly believe it but this field of sunflowers planted on 7/29 actually matured.

Sunflowers are now a weed clean-up crop in our rotations

Precision Mechanization

Vehicle control

Steering (Autosteer)

Steering

(assisted steering)

Implement control

Steering

(passive)

Steering

(active)

Planter row unit control

230 bu/ac in 2010

Strip intercropping

Jacob

Exciting developments are happening but the foundation of successful weed management in organic row crops will continue to be healthy crops and healthy soil