ABSTRACT
In the desert southwest and other warm-season turfgrass-growing regions of the United States, cool-season turfgrasses like perennial ryegrass and Poa trivialis are overseeded into dormant warm-season bermudagrass during fall. It is extremely important to control weeds prior to the overseeding to have a good stand of cool-season turf. During spring, when the temperatures start rising, herbicides may have to be used to control the cool-season turfgrasses so that the transition of the warm-season turf is not affected. Several herbicides can be used before overseeding and during spring transition, but the sulfonylurea (SU) class of herbicides has proven to be extremely versatile and useful. The SUs and imidazolinone classes of herbicides inhibit the acetolactate synthase (ALS) enzyme in the branched-chain amino acid biosynthesis pathway. These herbicides are extremely selective and can be used very effectively for weed management strategies before overseeding and can be used to control the cool-season turf during spring transition.
