BROWN BLIGHT

brown blight of perennial ryegrass	Characteristic	Description
	Host Grass Species	perennial ryegrass
	Month(s) with symptoms	March to May, Sept to Nov
	Stand Symptoms	spots, irregular distribution across turf stand
	Foliar Symptoms - Location/Shape	round or oval leaf spots, blighting of entire leaves
	Foliar Symptoms - Color	brown, yellow, tan
	Root/Crown Symptoms	none
	Fungal Signs	none

 

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

Brown blight is one of several Helminthosporium diseases which survive in thatch during periods that are unfavorable for disease development. These fungi are most active during periods of cool (60 to 65°F) and wet weather. Brown blight is most severe on turf that is growing slowly due to adverse weather conditions or improper management practices. Shaded areas with little or no air movement result in weak turf and extended periods of leaf wetness that favor infection and disease development. Deficient or excessive nitrogen, excessive thatch, extended periods of leaf wetness, drought stress, and mowing heights that are too low or too high encourage the development of Helminthosporium diseases. Certain cultivars of turfgrasses are very susceptible to injury from Helminthosporium diseases while many of the newly released cultivars exhibit good resistance.

CULTURAL CONTROL

Use turfgrass cultivars with resistance to this disease when available. Use of resistant cultivars is one of the best means of prevention. Select cultivars based on regional trials and University recommendations. Use blends and mixtures of cool-season grasses whenever possible. Fertilize to meet the nutritional needs of the turf but avoid over-stimulation and the development of lush, succulent growth. Do not apply more than one pound of nitrogen per 1,000 square feet in a single application. Mowing should be done within the recommended range for each turfgrass species. Keep the mower blades sharp to prevent open wounds through which the fungus can enter. Reduce extended periods of leaf wetness by watering deeply but infrequently to wet the entire root zone. Do not irrigate before sunset or after sunrise, and ensure good surface and soil drainage. Remove unwanted vegetation that impedes air movement and prune trees to allow for light penetration. Power rake or hollow-tine aerify to remove excessive thatch and reduce pathogen survival.

CHEMICAL CONTROL

Brown blight can be controlled on a preventative or curative basis. For best results, fungicides should be applied in the early stages of disease development.