Available at: https://digitalcommons.calpoly.edu/theses/88
Date of Award
MS in Agriculture - Plant Protection Science
Horticulture and Crop Science
Terry L. Vassey
White clover (Trifolium repens) is a common and difficult weed to control in turfgrass as it is a highly visible and unsightly weed that disrupts the uniformity of the turfgrass surface. This weed is a serious problem in the turfgrass industry in California and there is a need for better methods of control. With more regulations on pesticides and less information about efficient application techniques, controlling white clover with available herbicides can be difficult.
Compatibility trials were conducted during the summer of 2005 to determine the compatibility of the herbicides and adjuvants planned for use in subsequent greenhouse and field trials. A greenhouse trial was conducted in the spring of 2006, followed by field trials in fall of 2006 and spring of 2007 to determine the efficacy of two herbicides on white clover when combined with each of three adjuvants and two nozzles. Results showed the nozzles to have no significant effect on phytotoxicity to white clover in the greenhouse trial, while some of the herbicides and adjuvants significantly increased phytotoxicity to white clover. In the field trials, adjuvants had no effect on phytotoxicity, while some herbicides and nozzles significantly increased phytotoxicity to white clover, perennial ryegrass and common bermudagrass. Information about the combination of herbicides, adjuvants and nozzles will help turfgrass managers to improve their management of white clover in turfgrass.