We can help confirm resistance to herbicides and screen for susceptibility to alternative modes of action. Turf managers should collect a minimum of 25 plants for submission to our lab. It is recommended to sample from areas previously treated with a herbicide, particularly areas with segregation from susceptible or dying plants.
Methods. Screenings will be conducted in a greenhouse at the UGA Griffin Campus. Once received, plants will be placed in greenhouse flats and allowed to resume active growth. The traditional method for resistance screening includes dose-response evaluations. We generally apply about ten rates in a broadcast application to plants developed from tillers or seed of the original plants submitted. These are grown individually in separate pots with standard randomizations and replications. Hydroponic screenings are also used for confirmation of target-site resistance in grassy weeds. This system provides faster results than whole plant assays. Herbicides that can be screened hydroponically include ALS-inhibitors, dinitroanilines, and Photosystem-II inhibitors. The suspected resistant plants will be compared to a known susceptible biotype. We will also include another resistant biotype if available. Control is then evaluated at appropriate intervals for the mode of action tested.
Deliverables. Reports will be delivered with a summary of the methodology, results, pictures, and interpretation of the findings. The timeframe for delivering results will depend on the mode of action tested or the requested assay used for the work.
Goosegrass: ACCase-inhibitor resistance (sethoxydim, others)