Integrated Weed Control Strategies in Organic Farming

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Integrated Weed Control Strategies in Organic
Farming

• Jim Shrefler, OSU / WWAREC
• Charles Webber, USDA / ARS
• Warren Roberts, OSU / WWAREC
• Merritt Taylor, OSU / WWAREC
• Lane Agricultural Center

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Cooperators / Collaborators

• OSU Scientists, Specialists
• USDA Scientists
• Growers
• Noble Foundation
• Kerr Center

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While On The Soapbox

• Why do we want to do this?
• What are the problems with non-organic?
• Are we irrationally disregarding valuable
  technology?
• Will organics be problem free?
• Can exploration of organics lead to conceptually
  new ideas?
• What will the bottom-line be ..
• Should we consider multi-generation
  sustainability?

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Weed Control For Organics- Presentation Emphasis
-

• Yes - Crops
• Fruits
• Vegetables
• Herbs
• Row Crops
• No - Other Areas
• Forages
• Turf
• Ornamentals

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What is a Weed?

• Plant whose virtues are yet to be discovered
• A plant out of place
• Regardless, whether wild or cultivated,
  extraneous plants in a crop can reduce yield,
  quality and production cost

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General Management Factors

• Exclusion
• Elimination
• Prevent Establishment
• Removal
• Amelioration

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General Management Factors- Exclusion -

• Field selection
• Prevent new weedy species additions

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General Management Factors- Elimination -

• Prevent weed build-up
• Destroy propagules
• Solarization
• Fumigation
• Eradication For minor infestations of certain
  weeds

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General Management Factors- Prevent
Establishment -

• Herbicides
• Cultivation
• Cover crops
• Grazing
• Mulches
• organic and synthetic

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General Management Factors- Removal -

• Mechanical
• Chemical
• Physical
• flame
• steam

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General Management Factors- Amelioration -

• Crop Selection
• crops that tolerate weeds
• crops that enable control of weeds
• Give crop an edge
• transplants
• planting date

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So, what can we do under the constraints of
organics?
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Weed Management for Organics- Exclusion -

• Field selection
• a good choice
• knowledge needed of sites
• usefulness depends on available certified land
• Prevent weed additions
• critical for Organics
• bring-ins may contain weeds
• Organic mulches
• Raw manures

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Weed Management for Organics- Elimination -

• Prevent weed build-up
• timely cultivation, tillage
• purposeful plantings dont let weeds take over
• Weed population reduction
• perennial management through grazing
• fallow / tillage cycles
• solarization
• fumigants???

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Weed Management for Organics- Prevent
Establishment -

• Preemergence herbicides
• corn gluten meal, mustard meal
• Timely cultivation
• Stale seedbeds
• Cover crop management
• Species important e.g. rye
• Crop sequence (more detail later)
• Grazing
• Mulches
• organic and synthetic

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Weed Management for Organics- Weed Removal
Stop em in their tracks

• Mechanical cultivation
• keep it shallow
• minimize injury to the crop
• Improve the root zone
• Manual
• choose easy-to-use tools

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Weed Management for Organics- Weed Removal
(cont.)Stop em in their tracks

• Chemical vinegar, pelargonate, etc.
• currently just contact activity
• good foliage cover needed
• Physical energy consumers!
• flame
• special equipment, directed flame
• best for small, annual weeds
• steam

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Weed Management for Organics- Amelioration -

• Crop Selection
• use crops that tolerate weeds
• rapid growth, dense canopy
• crops that allow weed control
• sweet corn easily cultivated
• Give crop an edge
• plant date
• transplants

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Specific Examples of Tactics

• Cover crop management
• Preemergence herbicide
• Burn down chemicals

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Cover Crop Management

• Cereal Rye a classic example
• Effective due to
• Biochemical constituents
• Biomass
• Management involves
• Coordination of rye growth with crop plant date
  
• Rye destruction rolling?, tillage?
• Crop planting method

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Preemergence HerbicidesBioherbicides

• Corn Gluten Meal
• Makeup 9 nitrogen (fertilizer?)
• Available as powder, granule, pellet
• Weed control properties
• Certain peptides toxic to germinating seeds
• Works best under drying soil conditions
• Apply to surface or mix very shallowly

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Burn-down Chemicals

• Pelargonic acid is a leading option
• Also called nonanoic acid pelargonate
• Kills living plant tissue within hours
• Contact action not systemic
• Ammonium formulation for organic use
• Control
• Grasses Small before tillering is best
• Broadleafs varies with species
• No crop selectivity

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