2003 Season Review: Turfgrass Diseases

Richard Latin, Professor, Botany & Plant Pathology, Purdue University

A cool wet spring and moderate summer temperatures with two periods of heavy precipitation defined the turfgrass disease season for 2003. During the early spring, yellow patch (cool season brown patch) and necrotic ring spot were more prevalent than at any time during the past 5 years on creeping bentgrass/annual bluegrass golf greens. Outbreaks of melting out were common in lawn and low budget athletic turf during April and May. Turf managers normally to not address these diseases with fungicides, although there was at least one instance where a superintendent targeted a fungicide treatment towards necrotic ring spot. On golf courses, conditions during the first 3 weeks in May favored the establishment dollar spot on creeping bentgrass greens and fairways. Because of the relatively mild summer conditions, superintendents who did not avoid serious outbreaks in May seemed to battle dollar spot throughout the entire summer. Brief outbreaks of Pythium blight followed the heavy rains and high temperatures during the first week in July. The disease did not threaten again for the remainder of the summer. Initial outbreaks of brown patch also occurred shortly after the July 4 holiday; and the disease continued to develop intermittently through the Labor Day weekend (also marked by heavy rains). Brown patch symptom expression on creeping bentgrass fairways was quite severe compared to the previous 4 or 5 years.

Spring and summer of 2003 were also notable for the low incidence of summer patch and anthracnose on bluegrass species, and the absence of any confirmed reports of gray leaf spot on perennial ryegrass. Confirmed autumn diseases included leaf rust and dollar spot, both of which remained active into early November.