TURFGRASS DISEASE IDENTIFICATION (P11)
Other Fungal Diseases
Causal Agent: Sclerotinia homoeocarpa
Susceptible Turfgrass: All species of warm- and cool-season turfgrass
Symptoms: Dollar spot causes sunken, circular patches that measure up to 2 inches in diameter on golf greens and several inches on higher mown turf. The patches turn from brown to straw color and may eventually coalesce, forming irregularly shaped areas. Infected leaves may display small lesions that turn from yellow-green to straw color with a reddish-brown border. The lesions can extend the full width of the leaf. Multiple lesions may occur on a single leaf blade.
Conditions Favoring Disease: Dollar spot is favored by temperatures between 59°F to 86°F and continuous high humidity. This disease is particularly favored by warm days, cool nights, and intense dews. It also infects areas with low levels of nitrogen and becomes more severe in dry soils.
- Use an adequate level of nitrogen, particularly in the spring and early summer.
- Mow grass at regular intervals.
- Reduce thatch.
- Increase the air circulation.
- Irrigate turf deeply and as infrequently as possible to avoid drought stress.
- Remove dew from the turf early in the day.
- Convert to a turfgrass cultivar (especially for bentgrass) that is more tolerant to dollar spot.
- Apply contact and/or systemic fungicides on a preventive basis.
Occasionally occurs in: CA, OR, WA.
Frequently occurs in: AL, AR, AZ, CO, CT, DE, FL, GA, IA, ID, IL, IN, KS, LA, MA, MD, ME, MN, MO, MS, MT, NC, ND, NE, NH, NJ, NM, NV, OH, OK, PA, RI, SC, SD, TN, TX, UT, VA, VT, WI, WV, WY.
Fusarium Patch (Microdochium Patch)
Causal Agent: Microdochium nivale (same species that causes pink snow mold)
Susceptible Turfgrass: Most species of cool-season turf
Symptoms: Fusarium patch causes patches that are yellow or reddish-brown in color and 1 inch to 6 inches in diameter. The periphery of the patches are reddish-brown or pink in color. “Smoke rings”—thin, brown borders around the diseased patches that appear only in the early morning—can occur. The patches occur in cool, wet weather. Blighting in streaks can also occur as a result of spore tracking on equipment wheels.
Conditions Favoring Disease: Fusarium patch thrives in temperatures less than 60°F (but above 32°F) and in locations that experience more than 10 hours a day of foliar wetness for several consecutive days. It also favors areas high in nitrogen fertility and low in phosphorous and potash. Fusarium patch also infects areas with slow growing conditions and heavy thatch. Microdochium nivale is termed Fusarium patch when it occurs in the absence of snow cover.
- Maintain balanced fertility but avoid urea sources of nitrogen.
- Avoid using lime. Alkaline soils enhance disease development.
- Increase air circulation to speed turf’s drying process.
- Minimize the amount of shade.
- Reduce thatch.
- Apply fungicides prior to or at the first signs of disease. Turf recovery is more likely in the fall.
- Make additional fungicide applications as needed during the winter (without snow cover). Turf recovery is slow during the winter so maintain a fungicide program to reduce turf damage.
Occasionally occurs in: AL, AR, AZ, CA, FL, GA, LA, MS, NC, NM, OK, SC, TX.
Frequently occurs in: CO, CT, DE, IA, ID, IL, IN, KS, KY, MA, MD, ME, MI, MN, MO, MT, ND, NE, NH, NJ, NV, NY, OH, OR, PA, RI, SD, TN, UT, VA, VT, WA, WI, WV, WY.