Perplexing Perplexing Pigweed Problems Pigweed Problems in 2004 in 2004 Eric P. Prostko Eric P. Prostko Extension Weed Specialist Extension Weed Specialist Department of Crop & Soil Department of Crop & Soil Sciences Sciences University of Georgia University of Georgia Tifton Tifton
Perplexing Pigweed Problems in 2004. Eric P. Prostko Extension Weed Specialist Department of Crop & Soil Sciences University of Georgia Tifton. Pigweed Problems - 2004. Pigweed Problems - 2004. Why such a problem?. species timing a decline in DNA and Cotoran use in cotton - PowerPoint PPT Presentation
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Perplexing Pigweed Perplexing Pigweed ProblemsProblems in 2004 in 2004
Pigweed Response To HerbicidesPigweed Response To Herbicides ““Palmer amaranth more difficult to control than smooth”Palmer amaranth more difficult to control than smooth”
– Gossett and Toler (1999), Weed Technology 13:165-168
““Pendimethalin and trifluralin controlled Palmer amaranth, Pendimethalin and trifluralin controlled Palmer amaranth, redroot pigweed, and tumble pigweed less than other redroot pigweed, and tumble pigweed less than other herbicides”herbicides”– Sweat et al. (1998), Weed Technology 12:315-321
““Significant differences in herbicide control among pigweed Significant differences in herbicide control among pigweed species. Palmer amaranth is more difficult to control.”species. Palmer amaranth is more difficult to control.”– Mayo et al. (1995), Weed Technology 9:141-147
Identification of the Weedy Pigweeds and Identification of the Weedy Pigweeds and Waterhemps of IowaWaterhemps of Iowa– http://www.weeds.iastate.edu/weed-id/waterhemp/
default.htm
Pigweed Identification: A Pictorial Guide to the Pigweed Identification: A Pictorial Guide to the Common Pigweeds of the Great PlainsCommon Pigweeds of the Great Plains– http://www.oznet.ksu.edu/library/crpsl2/s80.pdf
Herbicide TimingHerbicide Timing
Palmer Amaranth Control with Blazer Applied at Palmer Amaranth Control with Blazer Applied at Different TimingsDifferent Timings
99
5748
0
25
50
75
100
3-5" 7-9" 11-13"
Weed Heigh t
Con
trol
(%
)
Source: Mayo et al., 1995 Source: Mayo et al., 1995 Weed Technology 9:141-147Weed Technology 9:141-147
Pigweed Control in RR SoybeansPigweed Control in RR Soybeans
more work is needed in more work is needed in this areathis area
Cadre Rate DilemmaCadre Rate Dilemma
64% of peanut acres 64% of peanut acres labeled use rate is 1.44 labeled use rate is 1.44
ozs/Aozs/A many growers using many growers using
1.0 ozs/A1.0 ozs/A cotton rotation is cotton rotation is
criticalcritical
Corn Production in GeorgiaCorn Production in GeorgiaAcres PlantedAcres Planted
2000
1080
600330
0
500
1000
1500
2000
2500
1974 1984 1994 2004
Year
Acr
es (
X 1
000)
Source: GA Crop Estimates (http://www.nass.usda.gov/ga/cropests/cornall.txt)
Crop Rotations in GACrop Rotations in GAIrrigated Peanuts Following Corn/Grain Irrigated Peanuts Following Corn/Grain
Sorghum or CottonSorghum or Cotton
0
15
30
45
60
75
1993 1995 1997 1999 2001 2003
Year
Acr
es -
%
Corn/Grain Sorghum Cotton
Source: UGA Extension Agent Surveys
Herbicide Resistant Pigweed IssuesHerbicide Resistant Pigweed Issues could be more of a problem could be more of a problem
than we think than we think DNA/IMI resistant DNA/IMI resistant
pigweed in SCpigweed in SC IMI/ALS resistant pigweed IMI/ALS resistant pigweed
in Burke County, GAin Burke County, GA no confirmed pigweed no confirmed pigweed
resistance to glyphosate resistance to glyphosate anywhere in world ?anywhere in world ?– Waterhemp in IA and MO
Final ThoughtsFinal Thoughts
resistant weed surveysresistant weed surveys weed control in reduced tillage systemsweed control in reduced tillage systems timing, timing, timingtiming, timing, timing use residual herbicides in problem fieldsuse residual herbicides in problem fields full rates of Cadre on difficult speciesfull rates of Cadre on difficult species corn rotations if profitablecorn rotations if profitable