NEW HERBICIDES OFFER NEW APPROACHES FOR WEED CONTROL IN DESERT TURFGRASSES. Kai Umeda*; University of Arizona, Phoenix, AZ (144)

Several new herbicide products have become available for use in desert turfgrasses recently or will soon be registered. Aminocyclopyraclor, marketed as Imprelis, has exhibited varying levels of efficacy against dandelion, burclover, black medic, wild celery, and mat chaff-flower at rates ranging from 0.075 to 0.15 lb a.i./A. Imprelis is safe on overseeded perennial ryegrass but is injurious to bermudagrass. Indaziflam, marketed as Specticle, is very effective in giving preemergence and very early postemergence control of Poa annua in dormant bermudagrass. Indaziflam showed a rate response with 0.067 lb a.i./A providing near complete control of P. annua and acceptable control achieved with 0.031 lb a.i./A. Flumioxazin, soon to be marketed as Sureguard is not yet registered for turf use, has been effective for preemergence control of P. annua in dormant bermudagrass. Fall applications of flumioxazin at 0.38 lb a.i./A were very effective against P. annua; however, rates as low as 0.19 lb a.i./A inhibited overseeded ryegrass turf establishment. Flazasulfuron is marketed as Katana for use in turfgrass for controlling purple nutsedge in bermudagrass with sequential applications at 0.047 lb a.i./A. It is also effective for use as a transition-aid herbicide to eliminate overseeded cool-season grasses from bermudagrass in the spring at rates from 0.0078 to 0.035 lb a.i./A. In dormant bermudagrass, it has exhibited efficacy in removing clumpy ryegrass and P. annua. Celsius is a three-way combination product that contains thiencarbazone, iodosulfuron, and dicamba. At product rates of 2.5 to 4.0 oz/A, it gave effective postemergence broadleaved winter weed control plus activity against P. annua and clumpy ryegrass in dormant bermudagrass.