Sweet Corn Herbicides

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Sweet Corn Herbicides Variety Sensitivity

• Doug Doohan, Joel Felix and Tim Koch OARDC,
  Wooster

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Focus

• Optimizing weed control
• using herbicides effectively
• varietal sensitivity

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Optimizing Weed Control

• Not depending entirely upon herbicides.
• Why not?
• Lose effectiveness
• Use too much

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Weed shifts / Resistance
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Optimizing Weed Control

• Use a variety of methods (Integration)
• Site Preparation
• Cultural Methods
• Chemical Methods
• Mechanical Methods

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Site Preparation
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Cultural Methods

• Prevention
• Eradication
• Crop Rotation

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Herbicides Options

• PREPLANT
• preplant burn down
• preplant incorporated (PPI)
• PRE - preemergence
• POST postemergence

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PREPLANT

• Preplant burn down
• late seeding following early seed bed preparation
• seeding into sod that wasnt killed previous
  autumn

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PREPLANT

• Preplant burn down
• glyphosate Gramoxone 2,4-D Banvel
• Can tank-mix with PRE herbicides

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PREPLANT

• PPI
• Why?
• Reduce dependence upon rainfall for activation
• Improve control of yellow nutsedge

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PREPLANT

• PPI
• Eradicane, Sutan -
• grasses, nutsedge, some broadleaf weeds
• Dual II Magnum, Frontier, Lasso/Pardner
• annual grasses, nutsedge, some broadleaf weeds

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PRE

• Atrazine max. rate 2.5 lb ai/A.
• Bladex legal until Dec. 31, 2002
• Dual many Dual products, Dual II is safer on
  corn
• Bicep premixes of Dual and atrazine with
  product range and features of Duals

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PRE

• Atrazine Bladex
• mainly broadleaf weeds
• PRE and POST activity
• triazine resistant biotypes
• carryover problems with atrazine
• Bladex can injure corn under plastic and if
  applied POST

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PRE

• Dual II Magnum
• Lasso
• Frontier
• annual grass herbicides, suppress nutsedge
• PRE with very little POST activity
• POST applications can slightly injury sweet corn
• Poor control of mid/late summer grasses

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POST

• Atrazine oil
• apply before crop is 12 inches
• Tank-mix with crop oil concentrate

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POST

• AIM
• weed control
• controls velvetleaf, nightshade, pigweed, annual
  morningglories and lambsquarters
• apply when weeds are 1-4 inches tall

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POST

• AIM
• crop Safety
• apply up to 8 collar stage on corn
• slight injury common
• position nozzles 18 inches above crop
• do not apply within 6-8 hours of rain
• do not spray into the whorl
• GROWER ASSUMES LIABILITY

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POST

• BASAGRAN
• Very safe to crop
• Non-residual
• Controls small broadleaf weed seedlings
• Timing Is Critical
• Suppresses nutsedge and thistles

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POST

• Dual - apply up to 5 leaf stage of the crop and 1
  leaf stage of grasses
• Frontier - apply to 12 inch tall corn but before
  weeds emerge.

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POST

• Permit
• Controls nutsedge, pigweed, velvetleaf, ragweed
  and cocklebur
• Non Ionic Surfactant required
• Cultivar sensitivities occur
• Do Not Apply During Periods of Water Saturated
  Soil
• Grower Assumes Liability

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POST

• Prowl
• controls triazine-resistant weeds and annual
  grasses when applied before emergence
• Plant corn at least 1.5 inches deep
• Apply at the spike stage or up to 12 inches high

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Sweet Corn Herbicides and Variety Sensitivity

• Sulfonyl Urea herbicides
• Accent, Beacon, Peak, Permit
• 1/10 cultivars may be severely injured
• reduced OR compromised detoxification
• Compromised by stress around the time of
  application
• High or low temperatures
• Water-logged soils
• OP insecticides

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Sweet Corn Herbicides and Variety
Sensitivity-OSU Research-

• 3 years of field research with Permit
• 15 cultivars
• injury and yield loss in 1/3 years (2000)
• Why bother?

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Permit(halosulfuron)

• 1 or 2 applications of 1 1/3 oz/A.
• 2/3 oz/A reduced tuber density by 80. (Nelson
  Renner)

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Conclusions - 2000

• Tolerant varieties at 1.33 oz/A included Kandy
  Corner, Ice Queen, Bandit, and Seneca Dancer.
• Tolerant varieties at 0.66 oz/A included Sweet
  Rhythm, Sensor, Extra Tender.
• Sensitive varieties included Fortune, Amazingly
  Sweet, Kandy King, Immaculata, Confection, and
  Silver King.

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2001

• 2000 OSU study was repeated with additional site
  in IN.
• non replicated study in MI

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Conclusions - 2001

• No yield reductions!
• Limited injury symptoms!
• Kandy King (13), Fortune (10)
• Amazingly Sweet, Immaculata, Confection, Sensor
  (trace)

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What to take home?

• Cultivar sensitivity is real and is uncertain
• Dont assume tolerance, use at own risk
• Environmental conditions are very important
• Stay tuned

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Wrap Up

• Optimize weed control and crop safety by
  integrating methods
• chemical, cultural, mechanical
• Herbicide options (preplant, pre, post) driven by
  individual situation analysis
• weed community, site preparation
• Growers assuming more management expertise and
  risk
• university research