ABSTRACT
This chapter will focus on common diseases and pathogens of creeping bentgrass, with an emphasis on those most troublesome in golf greens. There are no absolutes in turfgrass pathology. Diseases sometimes occur when not expected if weather conditions shift to favor the pathogen. For example, dollar spot normally appears in mid-to-late spring, but unusually warm night temperatures in early spring or late autumn can trigger the disease out of season. Another example is take-all patch. Take-all patch typically appears in new constructions about 2 years following seeding. The disease may intensify for several years and then naturally decline. There are many cases in which the disease is problematic for only a year or two and others where it persists for 10 years before declining. Diseases can be initiated by a pathogen in spring or even the previous autumn, but symptoms or damage may not become prevalent until the advent of warm and dry weather that stresses plants. These include root diseases like Pythium-induced root dysfunction and take-all patch. Brown patch and Pythium blight generally are most active during warm, wet, or humid periods in the summer, whereas dead spot and fairy ring are most destructive during periods of heat stress and drought. Appreciating the relationship among environmental conditions and season of the year, recognition of symptoms during the early stages of disease greatly facilitates œeld diagnoses and effective management. Invariably, diseases can and often do become problematic when unexpected. Golf course superintendents are cautioned to carefully monitor weather patterns, check “hot spots” where disease usually œrst appears, and use growing degree day or weather prediction models where available in an attempt to get ahead of their most chronic disease problems.
