Survey of Giant Ragweed Distribution and Spread in the North Central Region
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Transcript of Survey of Giant Ragweed Distribution and Spread in the North Central Region
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
(1852)
Date of first collection for herbaria
Date of reported herbicide resistance
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
In terms of management, how would you rate giant ragweed?
rMD = correlation with management difficulty, p < 0.05
Management Difficulty
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 .28Cotton: ns
What percentage of noncrop acreage 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 of crop 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
% of respondents answering yes
rMD = .11
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