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Trends In Peanut Weed Control. Dr. Eric P. Prostko Extension Weed Specialist University of Georgia Tifton. December 2002. Trends in Peanut Weed Control Topics for Discussion. tillage incorporation cultivation herbicide use reduced rates tank-mixes weed shifts resistance
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Trends In Peanut Weed Control Dr. Eric P. Prostko Extension Weed Specialist University of Georgia Tifton December 2002
Trends in Peanut Weed ControlTopics for Discussion • tillage • incorporation • cultivation • herbicide use • reduced rates • tank-mixes • weed shifts • resistance • R & D
Trends in Peanut Weed ControlTopics for Discussion • tillage • incorporation • cultivation • herbicide use • reduced rates • tank-mixes • weed shifts • resistance • R & D
Trends in Peanut Weed ControlStrip-Tillage Production Source: UGA Peanut Production Surveys
Strip-Tillage Weed Control • timing of burndown • paraquat, glyphosate, 2,4-D, Valor • yellow herbicides? • Incorporation • Florida pusley, evening primrose, Texas millet • perennial weeds?
Trends in Peanut Weed ControlTopics for Discussion • tillage • incorporation • cultivation • herbicide use • reduced rates • tank-mixes • weed shifts • resistance • R & D
Trends in Peanut Weed ControlHerbicide Incorporation Source: UGA Peanut Production Surveys
Herbicide Incorporation or Equally as effective Center-pivot irrigation is $2-7/A cheaper!
Trends in Peanut Weed ControlTopics for Discussion • tillage • incorporation • cultivation • herbicide use • reduced rates • tank-mixes • weed shifts • resistance • R & D
Trends in Peanut Weed ControlMechanical Cultivation Source: UGA Peanut Production Surveys
Why has mechanical cultivation declined? • disease management • better herbicides • time savings • strip-tillage increases • fuel prices
Trends in Peanut Weed ControlTopics for Discussion • tillage • incorporation • cultivation • herbicide use • reduced rates • tank-mixes • weed shifts • resistance • R & D
Trends in Peanut Weed ControlSoil-Applied Herbicides - I Source: UGA Peanut Production Surveys
Trends in Peanut Weed ControlSoil-Applied Herbicides - II Source: UGA Peanut Production Surveys
Trends in Peanut Weed ControlPostemergence Herbicides - I Source: UGA Peanut Production Surveys
Trends in Peanut Weed ControlPostemergence Herbicides - II Source: UGA Peanut Production Surveys
Trends in Peanut Weed ControlTopics for Discussion • tillage • incorporation • cultivation • herbicide use • reduced rates • tank-mixes • weed shifts • resistance • R & D
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 R&D and new products
The Response of Weeds to Various Cadre Rates in Georgia Applied EPOST (C-2LF) Webster et al. 1997
The Response of Weeds to Various Cadre Rates in Georgia Applied EPOST Webster et al. 1997
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
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
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.
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
Trends in Peanut Weed ControlTopics for Discussion • tillage • incorporation • cultivation • herbicide use • reduced rates • tank-mixes • weed shifts • resistance • R & D
Trends in Peanut Weed ControlTank-Mixes • herbicides • fungicides • insecticides • foliar fertilizers • reductions in time and money • may not be well researched or clearly labeled
Trends in Peanut Weed ControlTopics for Discussion • tillage • incorporation • cultivation • herbicide use • reduced rates • tank-mixes • weed shifts • resistance • R & D
Trends in Peanut Weed ControlWeed Shifts Top 5 Most Common Weeds in GA Peanuts
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 (Holm’s)
Tropical spiderwortHow bad is it????? Grady County, GA 2001
Trends in Peanut Weed ControlTopics for Discussion • tillage • incorporation • cultivation • herbicide use • reduced rates • tank-mixes • weed shifts • resistance • R & D
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 .
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 11:189-198
Biotechnology Varieties Planted in the US in 2002 Source:USDA/NASS June 2002
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
Trends in Peanut Weed ControlTopics for Discussion • tillage • incorporation • cultivation • herbicide use • reduced rates • tank-mixes • weed shifts • resistance • R & D
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?
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
University of Georgia Extension Weed Science (gaweed.com)