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Adjusting Herbicide Programs to Emerging Weed Problems in Peanut. Eric P. Prostko Extension Weed Specialist University of Georgia. Why do “new” weed problems occur?. reliance on herbicides decreases in cultivation ecological shifts herbicide resistance.
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Adjusting Herbicide Programs to Emerging Weed Problems in Peanut Eric P. Prostko Extension Weed Specialist University of Georgia
Why do “new” weed problems occur? • reliance on herbicides • decreases in cultivation • ecological shifts • herbicide resistance
New or Unique Weed Problems in Peanuts • tropic croton • dayflower/spider-wort • eclipta • copperleaf • spiderflower • redweed • ALS-resistant pigweed
Tropic Croton (Croton glandulosus) • 3rd most troublesome weed • Cadre is weak • not as competitive as other weeds • PRE - Valor or Strongarm • POST - Ultra Blazer • Cadre/Blazer tank/mixes???
Dayflower/Spiderwort (Commelina spp.) Asiatic • Berrien, Brooks, Grady, Thomas • limited data • Roundup is weak • PRE - Dual (timing) • POST - Basagran • others???? spreading spiderwort
8 7.6 6 Plants/ft2 4 2 2.2 0 Dual No Dual Residual Spiderwort Control in Peanuts with Dual Magnum, Brooks County, GA a b Dual Magnum @ 1 pt/A Applied: July 2, 2001 Rated: August 1, 2001
Eclipta (Eclipta prostrata) • low, moist areas • limited biology data • PRE - Strongarm, Valor, Dual, Outlook • POST - Basagran, Storm, Tough • timing is critical
100 80 60 2" or less Control (%) 3-5" 40 20 0 Storm Cadre Blazer Tough 2,4-DB Basagran Herbicide Eclipta Control in Peanuts with POST Herbicides Grichar, 1997
Hophornbeam Copperleaf (Acalypha ostryifolia) • Randolph, Terrell • limited biology data • PRE - Valor or Strongarm • POST - Ultra Blazer, Storm
Hophornbeam Copperleaf ControlRandolph County, GA - 2001 Untreated Strongarm Valor 6 WAT
Spiderflower (Cleome spp.) • Laurens County • limited data • PRE - Pursuit • POST - Pursuit, Cadre, Ultra Blazer (bloom stage)
Redweed (Melochia corchorifolia) • low, moist areas • hard seed coat • season long germination • PRE - Strongarm, Valor, Zorial • POST - Basagran, Storm, Cadre
ALS-Resistant Palmer Pigweed • Burke County • 2001 • do not use Cadre, Pursuit, Classic, Strongarm • Prowl, Sonalan, Dual, Valor, Ultra Blazer, Storm
Summary • Newer soil applied herbicides will help control some of the unique weed problems. • Combinations of PRE and POST treatments will provide consistent control. • Need more information about biology and competitiveness of newer weed problems in order to make better control decisions.
University of Georgia Extension Weed Science (gaweed.com)