DESCRIPTION OF THE DISEASE
Curvularia blight causes thinning out and decline of the grass; irregular patches and streaks may also occur. Leaves yellow and then become brown from the leaf tip down. Leaf spots can occur with symptoms most severe on older, senescing leaves. Roots, stolons and rhizomes may also become infected. A fine, grey layer of mycelia may cover infected tissues, and there is often an abundance of sporulation from infected and dead tissue. Spores are borne on the mycelia and no enclosed fruiting structures are formed.

SUSCEPTIBLE TURFGRASSES
Annual bluegrass, bermudagrass, bentgrass, and fescue are susceptible to curvularia blight.

CONDITIONS FAVORING DISEASE
The pathogen invades grasses through cut tips of leaves and is favored by high temperatures and adverse growing conditions. This is primarily a stress pathogen that attacks low fertility and heat and drought stressed plants. Damage often occurs when temperatures are 85°F or higher

MANAGEMENT
To prevent conditions that can lead to the development of curvularia blight, avoid both overwatering and drought stress by irrigating according to evapotranspiration needs of the turfgrass. Fertilize to promote moderate growth. Maintain as high a mowing height as possible and control thatch. Avoid planting shade trees in the surrounding area. Fungicides may be warranted on golf greens during long periods of high temperatures.

Cultural Control
Cultural practices can be important in preventing development of this disease. Apply the correct amount of fertilizer, reduce soil compaction, provide good soil drainage, and manage the thatch layer to keep it under 0.5 inches in thickness.

Treatment Decisions
There is little fungicide efficacy data available for the control of curvularia diseases in California. Both chlorothalanil and iprodione have been shown to be effective in other states.

Common name Chemical class

Many of these products are available for use by licensed applicators only and cannot be used by home gardeners.

A. CHLOROTHALONIL Chlorophenyl (multi-site)

B. IPRODIONE Dicarboximide

PUBLICATION

UC IPM Pest Management Guidelines: Turfgrass
UC ANR Publication 3365-T
Diseases
F. Wong, Plant Pathology, UC Riverside
M. A. Harivandi, UC Cooperative Extension, Alameda Co.
J. Hartin, UC Cooperative Extension, San Bernardino Co.
Acknowledgment for contributions to the disease section:
M. E. Grebus, Plant Pathology, UC Davis

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