LARGE PATCH

large patch sheath lesion in St. Augustinegrass	Characteristic	Description
	Host Grass Species	bermudagrass, centipedegrass, St. Augustinegrass, zoysiagrass
	Month(s) with symptoms	August to May
	Stand Symptoms	patches (1 foot to greater than 3 feet)
	Foliar Symptoms - Location/Shape	lesions on leaf sheaths
	Foliar Symptoms - Color	tan, yellow, orange, red
	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

Large patch begins to develop when soil temperatures decline to 70°F in the fall, but the symptoms do not necessarily appear at this time. The symptoms of large patch are most evident during periods of cool, wet weather in the fall and spring. In many cases, symptoms may not become evident until early spring when the warm season grasses are greening up. 

Large patch is favored by excessive nitrogen in the fall and spring, poor soil drainage, over-irrigation, excessive thatch accumulations, and low mowing heights. Centipedegrass is most susceptible to large patch, followed by zoysiagrass, and then St. Augustinegrass. Bermudagrass, rarely affected by large patch, recovers very quickly when the disease does occur. 

CULTURAL CONTROL

Establishment of a disease-resistant turfgrass species is the most effective means for management of large patch. Bermudagrass rarely sustains significant damage from large patch, and grows of out the symptoms quickly when the disease does occur. In contrast, centipedegrass, St. Augustinegrass, and zoysiagrass often sustain serious damage and recovery can take several weeks or months. Fescues and bluegrasses are immune to large patch and are also an option in areas where cool-season turfgrasses can be maintained.

Do not apply nitrogen to warm-season grasses in the fall and spring. These grasses are growing slowly during this time and do not require a significant amount of this nutrient. In general, nitrogen should not be applied to the warm-season grasses within 6 weeks before dormancy in the fall or within 3 weeks after green-up in the spring. Warm-season grasses vary in their fertility requirements, so refer to local University recommendations for more specific recommendations for timing and rates.

Avoid establishing warm-season grasses in low lying areas that remain saturated for extended periods of time from surface runoff. If this is necessary, install subsurface drainage to remove excess water from the soil. Irrigate only as needed to prevent severe drought stress in the fall and spring. Control traffic patterns to prevent severe compaction, and aerify as needed to maintain soil drainage and aeration. Mow at recommended heights, and power rake or vertical mow as needed to control thatch accumulations. 

CHEMICAL CONTROL

Fungicides are available for large patch control, but must be applied on a preventative basis. Applications should be initiated in the fall when soil temperatures decline to 70°F, regardless of when symptoms have appeared in the past. One or two well-timed applications provide season-long control of large patch in many situations. In severely affected sites, repeat applications should be made on 4 to 6 week intervals as long as soil temperatures are between 40°F and 70°F. Mapping of affected areas in the spring for spot-treatment in the fall can substantially reduce fungicide expenditures.

© North Carolina State University. This information sheet was prepared by Lane P. Tredway, Gail G. Wilkerson, Bridget R. Lassiter, Jenifer J. Reynolds, and Gregory S. Buol. Departments of Plant Pathology and Crop Science, College of Agriculture & Life Sciences, North Carolina State University. Prepared April 29, 2008. Available on-line at www.turffiles.ncsu.edu. This publication was made possible through a grant provided by the Center for Turfgrass Environmental Research & Education (CENTERE) whose purpose is to support worthwhile projects that will benefit both the private sector and the public, and protect the environment.