We sometimes see Pythium blight in our turfgrasses in Delaware during hot humid and wet weather. The following is more information.
With the recent hot, humid weather, Pythium blight has been reported on golf and landscape turf. Pythium thrives in low or poorly drained areas, especially when the night temperatures are above 68 to 700F. For best results, improve drainage, water in the early morning hours (midnight to 8 am), avoid over-fertilization, and apply Alude, Banol, Chipco Signature, Disarm, Headway, Heritage, Insignia, Koban, Magellan, mancozeb, Prodigy, Quell, Segway, Subdue MAXX, Terraneb SP, or Terrazole, according to the manufacturer’s recommendations. Caution: Koban and Terrazole can be phytotoxic during hot weather, so follow label directions carefully and experiment on a small area before treating large areas if using either product at this time of year.
Lawn infected with Pythium blight. Photo by William M. Brown Jr., Bugwood.org.
Information from Bruce B. Clarke, Ph.D., Specialist in Turfgrass Pathology, Rutgers University from the July 23, 2009 edition of Plant & Pest Advisory, Landscape, Nursery & Turf Edition from Rutgers University.