Gray leaf spot has become a popular topic the past several weeks as it moves north. It is now spreading through parts of Kansas and through the Ohio Valley.
Symptoms are most severe on perennial ryegrass during warm, humid weather. Severe outbreaks of the disease have been associated with prolonged leaf wetness (between 6-24 hours) and high temperature (70-90 degrees) stress. On perennial ryegrass all sward ages are susceptible with young seedlings, especially those receiving increased N, being most at risk.
Disease severity increases with turf under stress such as that brought about by herbicides, soil compaction, drought, and excessive nitrogen. Mowing height also appears to have an influence on disease development, although this factor seems to vary depending upon the region and species of turf.
TechNotes are provided by Sygenta GreenCast.
