Brown Patch

Symptoms & Signs

Stand symptoms manifest as circular to irregular patches that range from a few inches to a few feet in diameter. Patches are brown or tan in color on high cut turf and are brown to orange in low cut turfgrass. In higher cut turfgrass, the center of patched may begin to recover resulting in diffuse green turfgrass in the center of the patch.

Symptoms on individual plants varies between high and low cut turfgrass. On high cut turfgrasses leaf lesions have irregularly shaped borders with a chocolate brown border. Symptoms are not visible on leaves of low cut turfgrass.

On low mowed turfgrasses (i.e., putting greens), a “smoke-ring” of aerial white mycelium may be present on the margin of the patch on mornings with very high humidity.

When Does it Happen?

Brown patch occurs when daily low and high temperatures consistently exceed 75° and 90° F, respectively. Though, disease can begin to occur when daily lows exceed 60° F. The brown patch fungus requires leaf wetness periods of 10-12 h for several days for infection to occur. Factors that restrict air circulation and leaf drying favor brown patch development.

Cultural Management

Plant improved cultivars to reduce brown patch potential. Reducing leaf wetness periods can greatly reduce brown patch development, as the pathogen requires 10-12 h of leaf wetness to infect. Irrigate deeply and infrequently and in the early morning hours when turfgrass leaves are already wet. If possible, removing or pruning trees or shrubs restricting airflow can help reduce improve airflow and dry foliage. Dew removal practices, such as hose dragging or dew whipping, are good management practices to reduce leaf wetness periods on golf courses. Promote drainage through regular aeration practices.

Historically it was thought that brown patch was associated with excessive N fertilization in the summer months. Recent research from NC State suggests this might not be the case. In fact, combining 0.5 lbs N per 1000 ft2 in the summer months can help maintain turfgrass quality and help turfgrass recover.

Chemical Management

There are effective options for both preventative and curative management of brown patch. Though preventative programs are recommended for high-value areas. Preventative programs should begin when daily lows exceed 60° F. Curative applications may benefit from a supplemental light N application to encourage recovery of slow-growing cool-season turfgrasses.

Biological control agents are available and can reduce brown patch severity compared to not using anything. When utilizing biological control agents, applications should be initiated about 1 month prior to favorable weather for brown patch is expected. Ideally, biological control agent applications should be made 7 d apart and no more than 10 d apart.

Selected fungicides for brown patch management

¹ Trade products containing the same active ingredient(s) labelled for use on turfgrasses may be used according to label directions. Mention of specific products does not constitute endorsement.
² Always check product label for current use rates, application directions, and rate restrictions.
³ Relative efficacy. + = Marginally effective; ++ = Moderately effective; +++ = Effective; ++++ = Very Effective; ? = Limited information at this time.
⁴ Fungicide Resistance Action Committee code(s). Products sharing a code contain active ingredients with the same mode of action. Always use resistance management practices.