Herbicide Resistant Weeds

Uptake and translocation of [14C]MSMA in cotton and MSMA-resistant and -susceptible cocklebur.

Keese, R. J. and N. D. Camper. 1994. Uptake and translocation of [14C]MSMA in cotton and MSMA-resistant and -susceptible cocklebur. Pesticide Biochemistry and Physiology. 49: 138-145.

Common cocklebur (Xanthium strumarium) is a competitive weed which interferes with cotton production throughout the southeastern United States. A MSMA-resistant X. strumarium biotype was identified in S. Carolina. Absorption and translocation studies were conducted under laboratory conditions to compare MSMA-resistant (R) and -susceptible (S)-X. strumarium with tolerant cotton cv. Coker 315 using [14C]MSMA. Radioactivity was distributed throughout all plants and av. recovery from plants after 1, 3, and 5 d was 98, 70 and 85%, resp. The greatest concn of 14C activity was located in the treated leaf, with both acropetal and basipetal translocation occurring. There were no significant differences in radioactivity recovered from the 3 plant types. X. strumarium absorbed more MSMA than did cotton; most 14C activity was removed from the treated cotton leaf in the 1st water rinse. It was suggested that the cotton leaf cuticle plays a part in the MSMA tolerance mechanism. No significant 14C root exudations or 14CO2 evolution from intact plants was detected.