Common Name: summer patch
Scientific Name: Magnaporthe poae

The symptoms of summer patch appear in circular patches or rings, ranging from 6 inches to 3 feet in diameter. Turf within these patches is initially off-colored, prone to wilt, growing poorly, or sunken in the turf stand. Over a period of one to two weeks, the turf continues to decline, turning yellow or straw brown and eventually collapsing to the soil surface. The outer edges of the patch are usually orange or bronze when the disease is actively developing. Affected plants are easily pulled up from the turf, and visual examination reveals that the roots, crowns, and rhizomes are black and rotten. The patches recur in the same spot annually, and expand at a rate of 2 to 4 inches per year. Resistant grasses, such as creeping bentgrass, fescues, or weedy species, are often present in areas damaged by summer patch. In temperate climates, creeping bentgrass is resistant to summer patch and often remains completely healthy when surrounding annual bluegrass is attacked. Creeping bentgrass can become prone to the disease when grown in high-pH soils (>7.0) and subjected to persistent heat stress. Several cases of summer patch have been documented on bentgrass putting greens in the transition zone of the United States.
summer patch
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Characteristic Description
Host Turfgrass (1)creeping bentgrass, annual bluegrass, Kentucky bluegrass, fine fescue
Month(s) with symptomsJune to September
Stand Symptoms (10)spots, circles, patches (4 inches to greater than 3 feet), rings
Foliar Symptoms - Location/Shapedieback from leaf tip, blighting of entire leaves
Foliar Symptoms - Color (4)tan, yellow, orange
Root/Crown Symptoms (1)roots, stolons, rhizomes, and/or crowns dark brown or black
Fungal Signsnone
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