Trends%20In%20Peanut%20Weed%20Control

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Trends In Peanut Weed Control

• Dr. Eric P. Prostko
• Extension Weed Specialist
• University of Georgia
• Tifton

December 2002
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Trends in Peanut Weed ControlTopics for
Discussion

• tillage
• incorporation
• cultivation
• herbicide use
• reduced rates
• tank-mixes
• weed shifts
• resistance
• R D

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Trends in Peanut Weed ControlTopics for
Discussion

• tillage
• incorporation
• cultivation
• herbicide use
• reduced rates
• tank-mixes
• weed shifts
• resistance
• R D

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Trends in Peanut Weed ControlStrip-Tillage
Production
Source UGA Peanut Production Surveys
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Strip-Tillage Weed Control

• timing of burndown
• paraquat, glyphosate, 2,4-D, Valor
• yellow herbicides?
• Incorporation
• Florida pusley, evening primrose, Texas millet
• perennial weeds?

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Trends in Peanut Weed ControlTopics for
Discussion

• tillage
• incorporation
• cultivation
• herbicide use
• reduced rates
• tank-mixes
• weed shifts
• resistance
• R D

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Trends in Peanut Weed ControlHerbicide
Incorporation
Source UGA Peanut Production Surveys
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Herbicide Incorporation
or
Equally as effective Center-pivot irrigation is
2-7/A cheaper!
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Trends in Peanut Weed ControlTopics for
Discussion

• tillage
• incorporation
• cultivation
• herbicide use
• reduced rates
• tank-mixes
• weed shifts
• resistance
• R D

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Trends in Peanut Weed ControlMechanical
Cultivation
Source UGA Peanut Production Surveys
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Why has mechanical cultivation declined?

• disease management
• better herbicides
• time savings
• strip-tillage increases
• fuel prices

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Trends in Peanut Weed ControlTopics for
Discussion

• tillage
• incorporation
• cultivation
• herbicide use
• reduced rates
• tank-mixes
• weed shifts
• resistance
• R D

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Trends in Peanut Weed ControlSoil-Applied
Herbicides - I
Source UGA Peanut Production Surveys
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Trends in Peanut Weed ControlSoil-Applied
Herbicides - II
Source UGA Peanut Production Surveys
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Trends in Peanut Weed ControlPostemergence
Herbicides - I
Source UGA Peanut Production Surveys
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Trends in Peanut Weed ControlPostemergence
Herbicides - II
Source UGA Peanut Production Surveys
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Trends in Peanut Weed ControlTopics for
Discussion

• tillage
• incorporation
• cultivation
• herbicide use
• reduced rates
• tank-mixes
• weed shifts
• resistance
• R D

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What about reduced rates?

• not labeled but not illegal
• companies will not support failures
• not a guarantee to minimize crop rotation issues
• part of a total program
• future RD and new products

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Reduced RatesDo they work???
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The Response of Weeds to Various Cadre Rates in
Georgia
Applied EPOST (C-2LF)
Webster et al. 1997
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The Response of Weeds to Various Cadre Rates in
Georgia
Applied EPOST
Webster et al. 1997
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Hophornbeam Copperleaf ControlRandolph County,
GA - 2001
Strongarm 0.113 ozs Valor 0.75 ozs/A
Strongarm (0.45 ozs/A)
Valor (3 ozs/A)
Untreated
6 WAT
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Weed control in peanuts with reduced rates of
Strongarm and Valor, 2002.
Untreated
Valor 3 oz/A
Strongarm 0.45 oz/A
Strongarm 0.113 oz/A Valor 0.75 oz/A
Attapulgus, GA 7 WAP
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Reduced rates can work if..

• The weed is susceptible
• good growing/application conditions exist
• the application is timely (small weeds)

Full rates help to overcome variability of
application due to weed size, improper sprayer
calibration, environmental conditions, etc.
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What kind of grower might consider using reduced
rates?
A grower who ...

• regularly calibrates his sprayer
• has irrigation or can predict when it will rain
• gets consistent weed control at full rates
• understands the difference between 2 and 4
• can cover his acreage in a short time period
• is willing to scout his field regularly
• is willing to accept less than 100 weed control
• is not a lawyer or close friends with one

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Trends in Peanut Weed ControlTopics for
Discussion

• tillage
• incorporation
• cultivation
• herbicide use
• reduced rates
• tank-mixes
• weed shifts
• resistance
• R D

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Trends in Peanut Weed ControlTank-Mixes

• herbicides
• fungicides
• insecticides
• foliar fertilizers
• reductions in time and money
• may not be well researched or clearly labeled

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Herbicide/Fungicide Tank-Mixes
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Trends in Peanut Weed ControlTopics for
Discussion

• tillage
• incorporation
• cultivation
• herbicide use
• reduced rates
• tank-mixes
• weed shifts
• resistance
• R D

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Trends in Peanut Weed ControlWeed Shifts
Top 5 Most Common Weeds in GA Peanuts
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Tropical spiderwortCommelina benghalensis

• annual or perennial
• seeds and rhizomes
• above and below ground flowers
• 1600 seeds/plant
• high soil moisture and fertility
• problem weed in other countries (Holms)

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Tropical spiderwortHow bad is it?????
Grady County, GA 2001
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Trends in Peanut Weed ControlTopics for
Discussion

• tillage
• incorporation
• cultivation
• herbicide use
• reduced rates
• tank-mixes
• weed shifts
• resistance
• R D

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Herbicide ResistanceAround the World

• 261 Resistant Biotypes
• 157 Species (95 dicots and 62 monocots)
• over 210,000 fields

Source Heap, I. The International Survey of
Herbicide Resistant Weeds. Online. Internet.
December 2, 2002 .
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Herbicide ResistanceSoutheast
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Glyphosate ResistanceThey said it was unlikely!

• Horseweed
• DE (2000)
• TN (2001)
• Goosegrass
• Malaysia (1997)
• Italian Ryegrass
• Chile (2001)
• Rigid Ryegrass
• Australia (1996)
• California (1998)
• South Africa (2001)

Weed Technology, 1997 11189-198
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Biotechnology Varieties Planted in the US in 2002
SourceUSDA/NASS June 2002
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Herbicide Resistant WeedsStrategies for
Control/Prevention

• prevention is the key!!!
• utilize other weed control tactics (cultivation,
  row patterns, etc).
• rotate herbicides with different MOA
• rotate crops
• scout fields
• prevent seed production
• clean tillage and harvesting equipment

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Trends in Peanut Weed ControlTopics for
Discussion

• tillage
• incorporation
• cultivation
• herbicide use
• reduced rates
• tank-mixes
• weed shifts
• resistance
• R D

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Trends in Peanut Weed ControlR D

• have had a few good years (Cadre, Select,
  Strongarm, Valor)
• peanut is a minor crop
• only 2 products currently in pipeline (Spartan,
  Cobra)
• Will they make it?
• Do we need them?

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The Peanut Weed Control Toolbox
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The Future?My Predictions

• limited new herbicides
• 25 or less on herbicides
• increase in reduced rates and combinations
• new uses for older products
• increases in resistance
• weed shifts
• perennials
• unknowns

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University of Georgia
Extension Weed Science (gaweed.com)