Common Name: large patch
Scientific Name: Rhizoctonia solani

Large patch is a new name for an old disease. This disease was formerly called brown patch, the same disease that affects cool-season grasses during hot weather. Other than the fact that they affect different grasses, there are several important differences between brown patch and large patch that necessitated a name change: they occur at different times of the year, produce distinct symptoms, are caused by different strains of the fungus Rhizoctonia solani, and require very different control strategies. Large patch appears in roughly circular patches that are yellow, tan, or straw-brown. The patches are initially 2 to 3 feet in diameter, but can expand in size rapidly up to 10 feet or more in diameter, hence the name “large patch”. Multiple patches may coalesce to encompass even larger areas of turf. When the disease is actively developing, the outer edge of the patches are often red, orange, or bronze in color. Close examination of individual plants reveals the presence of reddish-brown or gray lesions on the leaf sheaths. It may be necessary to peel away the older, dead leaves in order to reveal the lesions on the younger leaf sheaths below.
large patch in zoysiagrass
[Click image to enlarge.]
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Characteristic Description
Host Turfgrass (24)bermudagrass, centipedegrass, St. Augustinegrass, zoysiagrass
Month(s) with symptomsAugust to May
Stand Symptoms (20)patches (1 foot to greater than 3 feet)
Foliar Symptoms - Location/Shape (3)lesions on leaf sheaths
Foliar Symptoms - Color (3)tan, yellow, orange, red
Root/Crown Symptomsnone
Fungal Signsnone
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