TURFGRASS DISEASE IDENTIFICATION (P14)
Other Fungal Diseases
Yellow Patch/ Cool Season Brown Patch
Causal Agent: Ceratorhiza cerealis (formerly Rhizoctonia cerealis)
Susceptible Turfgrass: Bentgrass, annual bluegrass, perennial ryegrass, bermudagrass
Symptoms: The symptoms of yellow patch (cool season brown patch) can vary depending on the grass cultivar, climatic and atmospheric conditions, soil, and intensity of the turfgrass management. This disease occurs from the fall through the spring or as the warm-season grasses approach or break dormancy, generally when air temperatures average 50°– 65°F. It causes rings and patches or circular patches that are yellow, light-brown, or reddish-brown in color and that measure 5 inches to several feet in diameter. Leaf lesions rarely occur and gray “smoke rings”—thin borders around the diseased patches—sometimes occur. Damage is generally superficial, but thinning can occur during prolonged periods of wet weather in late winter and early spring. Yellow patch can also be a problem on overseeded greens (Poa trivialis) in the southern states.
Conditions Favoring Disease: Yellow patch favors temperatures less than 60°F. It also occurs in areas that experience more than 10 hours a day of foliar wetness for several consecutive days. This disease is more severe in turfgrass with excessive thatch and high nitrogen levels.
- Improve soil drainage.
- Use low to moderate amounts of nitrogen, moderate amounts of phosphorous, and moderate to high amounts of potash.
- Increase the air circulation.
- Minimize the amount of shade.
- Reduce thatch.
- Use contact or systemic fungicides preventively for best results.
Occasionally occurs in: AZ, CA, CO, CT, IA, ID, IL, IN, KS, MA, ME, MI, MN, MO, MT, ND, NE, NH, NM, NV, NY, OH, OR, PA, RI, SD, VT, WA, WI, WV, WY.
Frequently occurs in: AL, AR, DE, FL, GA, KY, LA, MD, MS, NC, NJ, OK, SC, TN, TX, VA.
Susceptible Turfgrass: All turfgrass species mainly found on golf and bowling greens
Symptoms: Green or bluish-black in color, typically forming a thick mat on the ground surface. It can be peeled off, when dry.
Conditions Favoring Disease: Algae is very competitive in cool, moist, shaded locations. High surface moisture, inadequate drainage, and insufficient light and air movement also promote the growth of algae, as well as low fertility, high soil acidity, soil compaction, and excessive thatch. Algae can also be more problematic when using surface or retention pond water as often the algae may be present in the pond water. Some algal species are known to produce toxins which may contribute to turfgrass thinning.
- Increase mowing height and nitrogen fertility.
- Improve drainage and avoid frequent, shallow watering.
- Aerify compacted soils.
- In areas with less sunlight, plant shade tolerant grasses.
- Trim back shady trees and shrubs to increase air movement and light penetration.
Frequently occurs in: All states.