Cultural Management of Anthracnose Disease on Annual Bluegrass

turfgrass species throughout the world, but is particularly severe on weakened or senescent annual blue­ grass (Poa annua L.) turf. Anthracnose is caused by the fungus Colletotrichum cereale (Manns, Crouch, Clarke, and Hillman), which persists in turf as a saprophyte in thatch or infected plant material. Typically, the fungus can become pathogenic and infect leaf, stem, or root tissue when an environ­ ment of high humidity or extended leaf wetness coincides with plant stress. Symptoms can be observed throughout the year, but they are most intense between June and September in tem­ perate and transitional climatic zones. Annual bluegrass grown on golf course putting greens is a weak peren­ nial species that is known for its prolific production of seedheads, particularly between mid­April and June. Seed­ heads are unsightly, but more impor­ tantly, they also decrease the playability (smoothness and uniformity) of a putt­ ing green and deplete the carbohydrate (food) reserves of the plant by early summer. Consequently, carbohydrate­ starved annual bluegrass plants are thought to be more susceptible to anthracnose once summer conditions become more stressful (e.g., hot, humid, and/or droughty weather). The incidence and severity of anthracnose on annual bluegrass turf has increased in recent years through­ out the United States, particularly along the East Coast and in Midwestern states. In many cases, epidemics were so severe that fungicides have been unable to effectively control the disease when used at label rates and application intervals, resulting in extensive turf damage and major disruption to play, especially on putting greens. It is thought that changes in fungicide use patterns as well as management prac­ tices commonly employed on golf courses may be predisposing turf to anthracnose. It is probable that more than one or various combinations of management factors may be enhancing the severity of this disease and making it more difficult to control. Common manage­ ment practices thought to affect anthracnose severity include N fertili­ zation, mowing, rolling, chemical plant growth regulation, verticutting, top­ dressing, and irrigation. Our research program at Rutgers University has and is currently evaluating various aspects of these important cultural practices. The overall goal of our research is to develop a set of best management prac­ tices (BMPs) for the control of anthrac­ nose disease on annual bluegrass putt­ ing green turf. This article summarizes findings from a trial that evaluated the impact of N fertilization, two chemical growth regulators, verticutting, and the potential interactions of these factors on anthracnose of an annual bluegrass putting green.