Pink Patch

Pink patch has popped up at OSU turfgrass facility. Recently some rather unusual patches developed on 2 year old creeping bentgrass 'Penncross' maintained at fairway height.

Symptoms of pink patch, like those of red thread, often are more or less circular, pinkish red to tan patches, 2-4 inches in diameter. Pink patch, however, spreads much slow than red thread and is less severe. The damage generally is superficial. Individual leaves affected by pink patch become covered with a growth of fungal mycelium. The pink patch fungus does not produce red fungal threads or pink cottony masses of mycelium as does red thread.

Pink patch was once considered a form of red thread disease. The pink patch fungus and the red thread fungus are similar in appearance, and they often develop together. Hosts of the pink patch pathogen include species of bentgrass, fescues, ryegrass and bluegrasses.

The disease is caused by the fungus Limonomyces roseipellis.

The disease is more severe in turfgrass maintained with low nitrogen fertility. The fungus grows at temperatures from 40 to 90°F. Mild temperatures are often ideal especially if there is abundant moisture. The pathogen has a slow rate of growth and is more severe on slow growing stands of turfgrass

The disease is usually managed by increasing the growth rate of the turfgrass. An adequate fertility program based on soil tests is recommended. Many of the fungicides that work on red thread should be considered.

Authors: Joe Rimelspach, Todd Hicks, & Mike Boehm