Red Thread is Rampant!

June 10, 2010

Red Thread is RAMPANT!!!

Numerous calls and questions have been received about brown patches in lawns fromm many parts of the state.

Red thread is a foliar disease that usually occurs during spring and fall. Under the right conditions the disease may be seen in summer. The disease is often associated with susepetables grasses such as perennial ryegrass, fine fescue and some cultivars of Kentucky bluegrass BUT recently all cool-season grasses have been noted to have the disease including tall fescue and creeping bentgrass. Red thread symptoms create an undesirable appearance, but crowns and roots are not infected, so plants are not killed and turf eventually will recover.

Malnourished turf often has a chronic case of red thread. Deficient nitrogen and/or phosphorous fertility levels can result in serious outbreaks.

Red thread management:

- Genetic resistance to red thread infection is limited. Turfgrass varieties with different levels of red thread susceptibility are listed on the National Turfgrass Evaluation Program (NTEP) Web site:

- The most important nonchemical (cultural) control option involves implementing an adequate fertility program. A good fertility program implemented over two to three years will drastically reduce further red thread problems. If soil is low or deficient in phosphorous the disease is often severe.

- Other cultural practices that promote healthy turf and vigorous growth also help suppress red thread. Outbreaks may be reduced further by avoiding irrigation practices that extend dew periods (such as watering in the late afternoon and early evening).

- Fungicides may be used to control red thread if outbreaks occur on high maintenance turf or high value properties. QoI class fungicides (strobilurins) are very effective, especially when applied before sclerotia form. Flutolanil (ProstarĀ®) also is very effective. Repeated fungicide applications targeting red thread should be unnecessary if cultural control options are implemented. After a remedial treatment to suppress an unacceptable situation, the disease often can be managed with proper attention to nitrogen fertility.

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