Submitted to: Gordon Research Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 2/1/1999
Publication Date: N/A
Technical Abstract: The role of environmental temperature on the efficacy of the herbicide pyrithiobac was investigated. In field experiments it was determined that the efficacy was optimized when the temperature at application was between 20 and 35 deg C. Efficacy was significantly reduced when application temperature exceeded 35 deg C. Laboratory analysis of the thermal dependence of the inhibition of the herbicide's target enzyme, acetolactat synthase, indicated that the inhibition was thermally dependent. The temperature range for optimal inhibition of the enzyme by the herbicide was similar to that observed for herbicide efficacy in the field. It is proposed that the thermal dependence of the kinetics of the inhibition of acetolactate synthase by pyrithiobac may contribute to observed thermal limitations on herbicide efficacy.