Gray leaf spot resistance to fungicides spreading

Gray leaf spot resistance to QoI fungicides (Heritage, Compass, Insignia) has been documented in several locations around the U.S., and on both ryegrass and kikuyugrass-active strains of the fungus. Resistance to these products means that they are no longer effective, and alternative control methods need to be employed (Click here for a listing of effective products and programs for gray leaf spot).

Until a few weeks ago, California’s ryegrass-active strains of gray leaf spot appeared to have escaped the scourge…