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Survey of Giant Ragweed Distribution and Spread in the North Central Region. Regnier, E., C. Holloman, S. K. Harrison, M. Loux , R. Venkatesh , R. Ford, R. Taylor*, & F. Diekmann Ohio State University, Columbus, OH *Texas A&M University, Temple, TX. BACKGROUND.
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Survey of Giant Ragweed Distribution and Spread in the North Central Region Regnier, E., C. Holloman, S. K. Harrison, M. Loux, R. Venkatesh, R. Ford, R. Taylor*, & F. Diekmann Ohio State University, Columbus, OH *Texas A&M University, Temple, TX
BACKGROUND North American native riparian species Increasing problem in crop fields in the last 30 years
Hypothesized steps in spread of GRW • Spread from E to W • Adaptation from riparian to upland habitats • Spread from non-crop borders into crop fields • Evolution of prolonged emergence period • Facilitated by reduced tillage and POST herbicide
Survey of North Central States • Certified crop advisors • Distributed online by ASA • July 2013 • Exploratory data analysis • Mapping • Correlation analysis
Management Difficulty rMD = correlation with management difficulty, p < 0.05
Has herbicide-resistant GRW been suspected or confirmed (to ALS-inhibitors, to Glyphosate, to both)? Yes, confirmed Yes, suspected
Has herbicide-resistant GRW been suspected or confirmed? Management Difficulty Yes, confirmed Yes, suspected Corn, soybean, wheat: rMD = .19 to .28 Cotton: ns
What percentage of noncropacreage has giant ragweed present? rMD = .22
What percentage of crop acreage has giant ragweed present? rMD = .22
How long ago was GRW first observed in areas outside ofcrop fields? rMD = ns
How long ago was GRW first observed in crop fields? rMD = ns
In which non-crop environment did giant ragweed first appear?
In which non-crop environments have you observed giant ragweed?
Number of checked non-crop environments rMD = .18
Presence of giant ragweed in waterways rMD = .19 % of respondents answering yes
Presence of giant ragweed in fencerows rMD = .11 % of respondents answering yes
Correlation of GRW presence in non-crop habitat and resistance
When does giant ragweed first emerge as seedlings? rMD = -.22
Giant ragweed emergence period (months) rMD = .19
On what percentage of crop acreage is each of the following practices used?
Correlation of herbicide practice with GRW management difficulty
Correlation of perceived GRW resistance source with management difficulty
SummaryHypothesized steps in spread of GRW • Spread from E to W – from center outwards • Movement from crop borders into crop fields • Railroads, fencerows, ditch-banks, waterways • Adaptation to upland habitats – for over 20 yrs • Evolution of prolonged emergence period • Earliness and duration of emergence associated with increased management difficulty • Facilitated by reduced tillage and POST herb. • Reduced tillage associated with increased difficulty • POST – no association with management difficulty
Thank you to all those who reviewed our survey questions and participated in the survey! Funded by USDA - NCIPM