Managing Brown Patch of Tall Fescue in Home Lawns

Brown patch, caused by the fungus Rhizoctonia solani, is the most common disease of fescue lawns in Missouri. Disease symptoms generally develop in mid- to late June, following several days in which night temperatures are above 70 F, and leaves are wet for ten hours or more. In Missouri, the disease commonly occurs about mid-June. Symptoms range from circular areas to large irregular areas of blighted turf.

In the early stages of disease development, affected turf appears blue-gray to purple. At this stage, tan lesions with dark margins may be evident on individual leaf blades. As the fungus blights over the turf and the leaf blades rapidly fade to a uniform tan, the lesions are no longer evident. Brown patch is generally a sheath and leaf blighting disease. This means that there is potential for recovery, once temperatures become more moderate. Fescue often recovers without the use of fungicides; however, the disease is often unacceptable on high visibility, high maintenance lawns. When conditions remain favorable for disease development for long periods of time, the fungus can invade the crown, resulting in plant loss.

There are several cultural practices that can reduce disease severity. Do not apply more than 4 lbs of N per 1,000 square feet per year. Most of this total nitrogen should be applied in the fall. Heavy applications of nitrogen for spring green-up predispose the turfgrass to disease and moisture stress. Water in the wee hours of the morning when turfgrass leaves are already wet. Watering in the daytime or early evening extends the period of leaf wetness, which favors disease development. There are no fescue varieties that are highly resistant to brown patch, but some varieties such as ‘Adventure,’ ‘Arid,’ ‘Falcon,’ ‘Finelawn I,’ ‘Jaguar,’ ‘Olympic’ and ‘Trident’ may show less damage or recover more quickly.

It may not be possible to maintain a high profile fescue lawn without the use of a preventive fungicide program. There are several fungicides labeled for control of brown patch on home lawns. Two products that work well on a preventive basis are Bayleton and Prostar. Protection may last for 3-4 weeks. Begin preventive applications in early-June or when conditions are favorable for disease development.

Barb Corwin, Extension Specialist for Turfgrass and Ornamental Diseases, UMC (573) 882-1335