RED THREAD

red thread sclerotia	Characteristic	Description
	Host Grass Species	Kentucky bluegrass, tall fescue, fine fescue, perennial ryegrass
	Month(s) with symptoms	March to June, September to December
	Stand Symptoms	spots, circles, patches (4 to 12 inches)
	Foliar Symptoms - Location/Shape	dieback from leaf tip, blighting of entire leaves
	Foliar Symptoms - Color	red, pink, tan
	Root/Crown Symptoms	none
	Fungal Signs	thread-like sclerotia

 

Note: Still not sure if this is the right disease? The Turfgrass Disease Identification program may be helpful. Or consult the experts at the Turf Diagnostics Lab. Check the TurfFiles glossary for definitions of unfamiliar terms.

FACTORS AFFECTING DISEASE DEVELOPMENT

The red thread fungus is able to cause disease at temperatures ranging from 40 to 80°F, but develops most rapidly at approximately 70°F. Red thread affects grass that is growing slowly for any reason: inadequate fertilization, drought stress, cool weather, low light intensity, excessive traffic, or many other pest or environmental stresses.

Red thread is most severe in the spring and fall, when extended periods of cool, wet, and overcast weather slow growth of the turf and favor growth of the pathogen. Because of its wide temperature range, red thread can develop at any time of year when a slow-growing host and sufficient leaf wetness are available.

CULTURAL CONTROL

Fertilize to meet the nutritional needs of the turf and maintain vigorous growth. Submit a soil sample for nutrient analysis regularly, and apply recommended amounts of phosphorus, potassium, and lime. Apply nitrogen based on University recommendations to prevent weak, thin turf; however, avoid overstimulation and the development of lush, succulent turf.

Irrigation should be performed between midnight and 6 AM to prevent prolonged periods of leaf wetness. Never irrigate in the late afternoon or early evening. Apply a sufficient amount of water to wet the entire root zone, then reapply when the entire root zone is no longer moist. Prune or remove trees, shrubs, or other barriers to increase air movement and sunlight penetration. Remove clippings from affected areas when the disease is active to reduce spread of the disease, and wash infected clippings from equipment before entering uninfected areas.

CHEMICAL CONTROL

Fungicides are available for control of red thread, but are usually not necessary if proper cultural practices are implemented.