Throughout the Midwest, Helminthosporium melt-out is potentially active on Kentucky bluegrass lawns.
This disease initially appears on leaves as small leaf spots with a bleached out center with a purplish border. If disease severity is high, overall symptoms appear as a reddish-orange blighting and thinning of the turf. Optimum conditions for melt-out are cloudy humid/rainy days when temperatures range from 65 to 75 degrees Fahrenheit.
Culturally, the use of resistant cultivars is the most effective means for managing this disease. Other practices include using adequate - not excessive - nitrogen, and reducing the amount of thatch. If the disease is severe, fungicide applications would be warranted.
This article was reprinted from Syngenta's Green Cast TechNotes. For more information, visit www.syngentaprofessionalproducts.com.