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

Trends in Peanut Weed Control Topics for Discussion u tillage u incorporation u cultivation u herbicide use u reduced rates u tank-mixes u weed shifts u resistance u R & D

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

Strip-Tillage Weed Control u timing of burndown u paraquat, glyphosate, 2,4-D, Valor u yellow herbicides? u Incorporation u Florida pusley, evening primrose, Texas millet u perennial weeds?

Trends in Peanut Weed Control Topics for Discussion u tillage u incorporation u cultivation u herbicide use u reduced rates u tank-mixes u weed shifts u resistance u R & D

Trends in Peanut Weed Control Herbicide Incorporation Source: UGA Peanut Production Surveys

Herbicide Incorporation or Equally as effective Center-pivot irrigation is $2-7/A cheaper!

Trends in Peanut Weed Control Topics for Discussion u tillage u incorporation u cultivation u herbicide use u reduced rates u tank-mixes u weed shifts u resistance u R & D

Trends in Peanut Weed Control Mechanical Cultivation Source: UGA Peanut Production Surveys

Why has mechanical cultivation declined? u disease management u better herbicides u time savings u strip-tillage increases u fuel prices

Trends in Peanut Weed Control Topics for Discussion u tillage u incorporation u cultivation u herbicide use u reduced rates u tank-mixes u weed shifts u resistance u R & D

Trends in Peanut Weed Control Soil-Applied Herbicides - I Source: UGA Peanut Production Surveys

Trends in Peanut Weed Control Soil-Applied Herbicides - II Source: UGA Peanut Production Surveys

Trends in Peanut Weed Control Postemergence Herbicides - I Source: UGA Peanut Production Surveys

Trends in Peanut Weed Control Postemergence Herbicides - II Source: UGA Peanut Production Surveys

Trends in Peanut Weed Control Topics for Discussion u tillage u incorporation u cultivation u herbicide use u reduced rates u tank-mixes u weed shifts u resistance u R & D

What about reduced rates? u not labeled but not illegal u companies will not support failures u not a guarantee to minimize crop rotation issues u part of a total program u future R&D and new products

Reduced Rates Do they work???

The Response of Weeds to Various Cadre Rates in Georgia Webster et al Applied EPOST (C-2LF)

The Response of Weeds to Various Cadre Rates in Georgia Webster et al Applied EPOST

Hophornbeam Copperleaf Control Randolph County, GA WAT Untreated Strongarm (0.45 ozs/A) Valor (3 ozs/A) Strongarm ozs + Valor 0.75 ozs/A

Weed control in peanuts with reduced rates of Strongarm and Valor, Untreated Strongarm 0.45 oz/A Valor 3 oz/A Strongarm oz/A + Valor 0.75 oz/A Attapulgus, GA 7 WAP

Reduced rates can work if…….. u The weed is susceptible u good growing/application conditions exist u 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? u regularly calibrates his sprayer u has irrigation or can predict when it will rain u gets consistent weed control at full rates u understands the difference between 2” and 4” u can cover his acreage in a short time period u is willing to scout his field regularly u is willing to accept less than 100% weed control u is not a lawyer or close friends with one A grower who ……...

Trends in Peanut Weed Control Topics for Discussion u tillage u incorporation u cultivation u herbicide use u reduced rates u tank-mixes u weed shifts u resistance u R & D

Trends in Peanut Weed Control Tank-Mixes u herbicides u fungicides u insecticides u foliar fertilizers u reductions in time and money u may not be well researched or clearly labeled

Herbicide/Fungicide Tank-Mixes

Trends in Peanut Weed Control Topics for Discussion u tillage u incorporation u cultivation u herbicide use u reduced rates u tank-mixes u weed shifts u resistance u R & D

Trends in Peanut Weed Control Weed Shifts Top 5 Most Common Weeds in GA Peanuts

Tropical spiderwort Commelina benghalensis uannual or perennial useeds and rhizomes uabove and below ground flowers u1600 seeds/plant uhigh soil moisture and fertility u problem weed in other countries (Holm’s)

Tropical spiderwort How bad is it????? Grady County, GA 2001

Trends in Peanut Weed Control Topics for Discussion u tillage u incorporation u cultivation u herbicide use u reduced rates u tank-mixes u weed shifts u resistance u R & D

Herbicide Resistance Around the World u 261 Resistant Biotypes u 157 Species (95 dicots and 62 monocots) u over 210,000 fields Source: Heap, I. The International Survey of Herbicide Resistant Weeds. Online. Internet. December 2, 2002.

Herbicide Resistance Southeast

Glyphosate Resistance They said it was unlikely! u Horseweed * DE (2000) * TN (2001) u Goosegrass * Malaysia (1997) u Italian Ryegrass * Chile (2001) u Rigid Ryegrass * Australia (1996) * California (1998) * South Africa (2001) Weed Technology, :

Biotechnology Varieties Planted in the US in 2002 Source:USDA/NASS June 2002

Herbicide Resistant Weeds Strategies for Control/Prevention u prevention is the key!!! u utilize other weed control tactics (cultivation, row patterns, etc). u rotate herbicides with different MOA u rotate crops u scout fields u prevent seed production u clean tillage and harvesting equipment

Trends in Peanut Weed Control Topics for Discussion u tillage u incorporation u cultivation u herbicide use u reduced rates u tank-mixes u weed shifts u resistance u R & D

Trends in Peanut Weed Control R & D u have had a few good years (Cadre, Select, Strongarm, Valor) u peanut is a minor crop u only 2 products currently in pipeline (Spartan, Cobra) u Will they make it? u Do we need them?

The Peanut Weed Control Toolbox

The Future? My Predictions u limited new herbicides u $25 or less on herbicides u increase in reduced rates and combinations u new uses for older products u increases in resistance u weed shifts –perennials –unknowns

University of Georgia Extension Weed Science (gaweed.com)