Red thread/pink patch disease generally occurs when weather is cool, wet and overcast, usually in the spring and fall. These diseases are more pronounced under low soil fertility. The application of a balanced fertilizer can greatly reduce disease severity. However, these diseases can also be troublesome in soils managed under moderate to high soil fertility. In that case, if environmental conditions persist, one to two fungicide applications should minimize the severity of the diseases.
Red Thread is most common to Fescues, Ryegrasses, and Kentucky Bluegrasses. Red Thread gets its name from the pinkish-red threads that form around the leaf blades and bind them together. Eventually, the affected grass will turn brown and the red treads will be most visible when wet.
The best prevention for Red Thread is aerate often and remove thatch. Mowing to proper levels, reduce shade on lawn, follow a regular fertilization schedule. Including potassium in the fertilization program may help mildly cases.
The most common fungicide used on Red Thread is chlorothalonil.
Pathogens: Laetisaria fuciformis and Limonomyces roseipellis
Primary Hosts: Perennial ryegrass, Kentucky bluegrass, creeping red fescue and tall fescue
Environmental Conditions Conducive to Disease Development: Cool, wet, overcast conditions primarily in the spring and fall.
Red thread and pink patch, while caused by two different organisms, generally incite the same symptoms in a lawn. The physical presence of the pathogen causing red thread is described by its name. As the mycelium dries down on the infected turf it forms red sclerotia, or resting structures of the fungus, at the infected tips of the grass. The mycelium of the pink patch fungus tends to have the appearance of cotton candy intertwined within the turfgrass canopy and has a reddish pink color to it.