Red Thread

Disease

Laetisaria fuciformis


Red thread is a disease of slow growing turf. Red thread is easily recognized by the red to coral-pink fungal strands (stromata) produced on leaf blades and sheaths. When turf is wet, the fungal stroma looks gelatinous and fleshy. As the grass dries, the stroma also dries and becomes thin and thread-like. Infected turf often appears to be suffering from lack of water, often times symptoms resemble dollar spot. Under close examination of the grass blades reveals red to coral-pink stromata. Under conditions of high humidity, pink cottony flocks of arthroconidia can be seen in the patches.

Red thread occurs is favored by high humidity at temperatures between 60°-90° F (15.5° and 32° C). Cool, drizzly days of spring and fall are ideal for the development, and the disease spreads from plant to plant by growth of the stromata. These can be spread by wind, and mechanical equipment.

  • Crops Affected: Turfgrass

    Damage

    The location of this disease is home lawns and golf courses. General symptoms are a spot, patch, or irregular coloring. Foliar symptoms are browning. This can occur during the months of March, April, May, June, July, August, September, and October. Hosts of the disease are Kentucky Bluegrass, Perennial Ryegrass, Fine Fescue, Creeping Bentgrass, and Annual Bluegrass.

    Management

    Adequate nitrogen fertility is important in managing red thread (Variations exist among turfgrass species in nitrogen fertilizer recommendations). Adequate nitrogen levels should be applied, particularly during the summer months, so that in the fall, turfgrass will be less susceptible to red thread. Nitrogen fertility in the spring and fall should be applied with caution in areas susceptible to Microdochium patch and Typhula blight.

    Drought stress should be avoided with adequate irrigation. Collecting of turfgrass clippings during periods when grass is growing slowly may reduce the levels of inoculum incorporated back into the turf.

    Red thread sometimes requires some type of chemical management if severe enough. Also, if nitrogen is applied in the fall in order alleviate red thread symptoms, it is likely that a fungicide program will need to be in place for Microdochium patch and Typhula blight (in cool climates). Fungicide chemistries that are used for red thread include Iprodione, anilazine, chlorothalonil, triadimefon, fenarimol, propiconazole, myclobutanil.