Paraquat-Resistant Horseweed Identified in the Mid-Atlantic States
- Mark J. VanGessel *,
- Barbara A. Scott and
- Quintin R. Johnsona
In 2003, a small percentage of horseweed (Conyza canadensis) plants survived sequential paraquat applications in a research trial conducted in a commercial field. This research project focused on determining if this horseweed population was resistant to paraquat. The susceptible biotype required a paraquat application of 0.03 lb ai/acre to reduce biomass by 50%, while the suspected-resistant biotype required 0.7 lb ai/acre. This consists of a 22-fold difference in response between the two biotypes. This is the first documented case of paraquat-resistant horseweed in the Mid-Atlantic states and the second reported case in the United States for this species.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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