What causes Brown Patch or Large Patch Lawn Disease?
Brown Patch or Large Patch lawn disease is caused by various strains of soil borne fungus, Rhizoctonia solani, and can effect all South Carolina turf grasses. The fungus is most commonly found in Bermuda, Kentucky Bluegrass, Centipede Grass, Bentgrass, St. Augustine, and ryegrasses in regions with high humidity and/or shade. Tall fescue is also prone to the development of Brown Patch. Ideal conditions for development are consistently warm nighttime temperatures, 60+ degrees, and daytime between 75-85 degrees combined with wet/humid conditions. How lawns are grown, including application of nutrients, irrigation practices, types of cultivation, etc… will also impact the spread of brown patch.
Brown or Large Patch symptoms can vary with different grass and soil conditions. The diseases usually cause patches of light brown grass that are circular in shape. The infected areas can range from a few inches to several feet in diameter.
The best preventative against brown patch or large patch is good lawn care practices; Keeping lawns mowed to the proper height for the grass species, avoid high rates of nitrogen fertilizer on cool season grasses in late spring/summer and on warm season grasses in mid/late fall and early spring. The disease causing fungus attacks the growth of grass which nitrogen promotes. It is very important to insure the proper form and amounts of nitrogen are used.
Due to the fast spreading of disease when moisture is present for longer then 10 hours, watering early in the morning is advised. The disease may be worse if the soil pH is less than 6.0.
Having a lawn care/landscaping professional is one of the best ways to address this and many other lawn care issues.
Sources
http://www.cals.ncsu.edu/plantpath/extension/fact_sheets/Turfgrass_-_Managing_Brown_Patch_in_Tall_Fescue_Landscapes.htm
http://www.american-lawns.com/problems/diseases/brown_patch.html
http://www.clemson.edu/extension/hgic/pests/plant_pests/lawns/hgic2150.html
