This is a slightly edited version of a presentation that I shared at the Organic Farming Conference in La Crosse WI on Friday 2/24/2012

1. Systems strategies for organic
weed management
Crop
Joel Gruver (309) 298 1215
WIU Agriculture J-gruver@wiu.edu

2. Who is sleeping in your soils?

4. Which weeds would emerge if you
brought soil inside right now?

5. The soil bud bank
Besides seeds, other dormant meristems, propagules, may
accumulate in the soil in large numbers:
-bulbs
-bulbils (aerial bulb; e.g. lillies)
-buds on rhizomes (e.g. quackgrass)
-corms (enlarged, rounded, underground stem)
-tubers (e.g. jerusalem artichoke)
-buds on rootstocks (e.g. common milkweed, hemp dogbane)
Difference between bud and seed banks:
-buds are clonally reproduced, and as such are of the same genotype
successful in leaving buds in the soil
-seeds buried in the soil are potentially new genotypes, potentially
untested; exception: self-pollinated weed seed species

6. Does an inform your
understanding weed
of seed/bud management
dormancy decisions?

7. Seed rain Are you
managing
Seedlings
the whole
cycle?
Predation Active
Seed-
Dormant bank
seedbank
Senescence
&
Decay
Death

8. 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

9. Conservation Activation
Suppression
3 broad goals of
ecological Augmentation
management

10. Direct control strategies
vs.
Cropping system strategies

11. ABCs of mechanical and
cultural weed management
Page 11 – Steel in the Field
A. Give the crop the advantage.
B. Keep weeds on the defensive.
C. Accept weeds that don’t really
matter.
Excellent reference describing
equipment for direct control of
weeds

12. Cropping system strategies
Crop rotation
Tillage rotation
Cover cropping
Fertility/manure management
Field/equipment/seed sanitation
Crop establishment and management

13. Optimize crop establishment to maximize
competitive advantage
-Select well adapted varieties (maximum
leafiness and rate of canopy closure)
-Delay planting (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?

14. Preventive management
• Flush soil seed bank with fallow periods
• Walk crops
• Employ alternative equipment for mowing,
pulling weeds
• Weedy crops -> forage or cover crops

16. Ridge-till is a great example of a time-tested
“cropping system” strategy for reducing weed pressure
Why aren’t more organic
farmers using ridge-till? Direct control

17. Long-term controlled traffic before GPS

18. No pre-plant tillage intended for this experiment
Ridge till and No-till
soybean strips
should require no pre-plant
tillage this spring

19. Terminating spring planted oats with a soil finisher
~ 3 weeks before planting corn
GOAL = biological activation and suppression

20. No one hammer is likely to provide
acceptable weed control
Effective
Integration of
organic weed =
many little hammers
management
Direct control strategies are much
more likely to provide acceptable
weed control if cropping system
strategies have reduced weed
pressure

21. Effective strategies consistently and
persistently disrupt weed life cycles

22. Successful organic
farming takes a high level
of skill and will!

23. 15 interviews
completed
2
1
3
5
3

24. 15 interviews completed (14 farmers, 1 consultant)
organic
Name Location years farming acres livestock
beef, hogs, chickens,
Earl Hafner Panora, IA ~35/12 1800 tilapia
Paul Mugge Sutherland, IA 35/13 300 none
Scott Shriver Jefferson, IA 17/13 1800 none
Jack Erisman Pana, IL >40/22 ~2500 beef
Ted Weydert Dekalb Cty, IL 36/12 285 none
Marvin Manges Yale, IL 34/25 1000 beef
Clay Nielsen Atkinson, IL 22/7 75 beef
Jeff Glazik Paxton, IL 15/8 400 beef
Mike Findley Caro, MI 40/15 2200 none
Steve McKaskle Braggadoccio, MO 39/21 1700 none
Larry Shrock Middleton, MO 38/17 650 beef
David Munsterman Montrose, MO 25/14 560 beef
Lynn Brakke Moorhead, MN 31/19 ~2200 beef
Lee Thomas Clay Cty, MN 30/10 1160 sheep, chickens
8 farms > 1000 acres & 3 farms > 2000 acres

25. Basic biographical and background info:
Name:
Educational background:
Farm location:
Years farming: Years farming organically:
Organic crops and acreage:
Conventional crop and acres if applicable:
Livestock enterprises:
Organic certifying agency:
Standard crop rotation(s) for organic crops:
Standard tillage practices for organic crops:
Most challenging weeds in organic fields:

26. Questions about direct weed control tactics:
o What cultivation tools do you use on your farm? Please
briefly describe how you use each tool (crops, timing,
adjustment, ground speed, mechanical or GPS
guidance…) and your level of satisfaction.
o Do you have any experience with flame weeding? If so,
please explain.
o Do you have experience with any “organic” herbicides?
If so, please explain.
o Is manual labor (e.g., walking beans) part of the weed
management on your farm? If so, please explain.

27. Questions about cropping system strategies for reducing weed
pressure:
o What role does primary tillage play within your overall approach
to organic weed management?
o What role does crop rotation play within your overall approach to
organic weed management?
o What role do cover crops play within your overall approach to
organic weed management?
o Do you use any specific methods of depleting the soil seed bank
(e.g., fallow, stale seed bedding…? If so, please describe.
o Do you have any specific clean-up strategies following weed
control disasters?
o Do you specifically select crop varieties/hybrids for competitive
advantage over weeds?

28. Additional questions:
o How are your standard organic weed management practices affected by
extended wet conditions? Have you developed any effective techniques for
controlling weeds organically during wet conditions?
o How different are your weed management practices from other organic grain
farmers you know?
o Do you know any organic farmers who seem to be particularly skillful weed
managers? If so, what do you think gives them the edge?
o What are your sources of information about organic weed management? (e.g.,
books, conferences, other farms, websites, and etc.)
o Are you considering any new weed management strategies? If so, please
explain
o Are there any specific aspects of organic weed management that you think
need more research? If so, please describe?
Do you have any additional comments to share about organic weed
management that might benefit other organic farmers?

29. Are there other
questions that we
should be asking?

30. Nearly all farmers delay planting until they
have killed one or more flushes of weeds
What can we do to maximize this flush?
Not all tillage operations have the same effect

31. Establishing a good stand is key!!

33. Nearly all of the farmers use rotary hoes
30’ rotary hoe

34. About half of the farmers use tine weeders

35. Rotary hoes and flex-tine weeders
are most effective when the soil has a crust
Some crop damage is inevitable but care should be
taken to avoid times when crop is most fragile

36. More than half of the farmers
regularly use a flame weeder
Terminating weeds without awakening sleeping seeds

37. All use inter-row cultivation

38. JD 730 Air-Disk drill on Jack Erisman’s farm in Pana, IL
Jack uses this rig to drill soybeans on 6" rows (~ 280,000/ac) while
also dropping about 2 bushel of rye and some micronutrients

39. Some of the farmers using rolling baskets and other
alternative cultivation tools

40. 2 of the farmers use mechanical
guidance and 3 use GPS guidance to
increase accuracy and reduce operator
stress during cultivation

41. Scott Shriver (Jefferson, IA)
We have 4 tractors that can run in the crop and at times
all four are in use. Two of these are set up with RTK
Guidance. We plant with the Guidance which makes our
rows more straight, which in turn makes the cultivating
easier and allows us to set equipment tighter. Cultivating
with the guidance is not completely automatic, but
allows us to run faster and look behind more without
doing as much damage to the crop. Another thing I
highly recommend is a hydraulic 3rd link on your tractor.
This makes changing cultivator depth, rotary hoe and
tined weeder pressure adjustments much easier, thus
they can be done more frequently and on the go.

42. Mike Findley (Caro, MI)
He has 2 Orthman single sweep cultivators, which had
16” sweeps before he used RTK guidance on his tractor.
He is on 22” row crop spacing and with GPS guidance
can cultivate as fast as 5 mph using 18” sweeps leaving
only 2” on either side of the crop to get weeds close to
the crop. He feels that having a 16 row mounted
planter (on 3 point hitch) also helps keep the planter
from moving off a straight line especially on rolling
ground, which helps make cultivating even more
successful. A 60’ wide tine-weeder is used about 4 days
after planting to control small weeds. He also made a
double rotary hoe a couple years ago that is used for
weed control.

43. Lynn Brakke (Moorhead, MN)
He plants on 22” rows and can cultivate within 1 ½” on
each side of the crop row using RTK guidance and
mechanical guidance on the cultivator that allows the
cultivator to move side to side independently. He can
cultivate as fast as 10 mph. He may use a rotary hoe for
weed control up to 4 times if needed. A Melroe spring
tooth harrow is sometimes used, especially when the
weeds are too big for the rotary hoe and if grass is too
abundant. This tool can be used on soybeans as tall as
10”.

44. Essentially all of the farmers plant small grains

45. Frost seeded clover
the most tried and true
cover cropping system
in the Midwest region

46. Where are the soybeans??
Traditional organic weed management often
comes up short during wet years

47. Days Suitable for Field Work
http://agebb.missouri.edu/mgt/fieldwork.htm
Timely field operations are especially
important in organic farming systems
The past 3 seasons
have had far fewer
days suitable for field
work than normal

49. September October
Tillage System Experiment at the WIU organic research farm
November January

50. Options for rolling cover crops
Rodale design Our roller in 2010
Cultimulcher

51. Early June
1 week later

52. ~2 weeks after planting

53. July
August late September

54. Early November
Plot yields ranged from 51.6 to 58.6 bu/ac
No significant differences between systems

55. November 2010
Significant foxtail pressure
but almost no broadleaf weeds
Plot yields ranged from 42-52 bu/ac

56. Early June 2011
We planted before
rolling in one set of plots

57. 15’ wide roller built by a local farmer

58. Mid-June 2011

59. Early July 2011

60. Our conventional-till beans are
looking good, right?
Unfortunately, there were lots of in-row weeds :-<

61. August 2011

62. November 2011
No-till bean plots averaged 43 bu/a
~ 10 bu/a higher than then next
highest treatment in this experiment

63. 7/17/2010 planting
After ~ 300% of normal rain in May, June and
July 2010 we ended up planting sunflowers on
most of our acres planned for corn

64. Both 2010 planting dates matured with an average yield 7/29/2010 planting
> 1500 lbs/a. We planted sunflowers on 7/7 in 2011 and
plan to continue using sunflowers as a strategy for
cleaning up fields with high weed pressure.

65. Cereal rye inter-seeded with soybean for in-row
weed control at the Allison Farm
No significant differences in yield between 20 and 40 lbs/a
of rye in row vs. 60 lbs broadcast vs. control
(all trt means > 40 bu/a)
Cereal rye and several other CC species that require
vernalization will be planted over soybeans rows using the
insecticide boxes on our planter in 2012

66. Do all parts of your farming systems contribute
to effective weed management?