Every lawn eventually becomes the victim of lawn grass disease from the well-manicured expanse of the golf course to the sometimes-neglected backyard. This problem is devastating for the landowner following a large investment in establishing and caring for his turfgrass. However, the destruction of lawn grass infection is not beyond repair.
General Cause and Prevention
Lawn diseases, like human diseases, infect susceptible hosts. Similarly, the identification of lawn diseases is difficult at times, because they do not always display distinct characteristics tending to manifest with the same symptoms. Grasses vary in their resistance to disease; however, when environmental conditions are favorable to specific pathogens, infection occurs. Proper watering, mowing, aeration, sunlight and fertilization help to prevent or control problems by providing a disease-resistant environment.
High-Humidity Grass Diseases
Brown Patch: This lawn grass disease commonly infects most grasses initially manifesting as a small patch of wet, dark grass before progressing to circular or horseshoe-shaped patches of brown grass encompassed by a yellowish ring. The patches rapidly expand, advancing in size up to several feet in width. According to American-Lawns.com, this disease thrives in daytime temperatures of 75 to 85 degrees and evening temperatures over 65 degrees. Brown Patch disease responds well to consistent fertilization, early morning watering, keeping the grass a bit high and bagging lawn clippings to prevent contamination of areas previously infected. Healthy grass subsequently returns upon elimination of the infection. Use of fungicide before infection occurs serves as a preventive measure.
Dollar Spot: Dollar spot thrives in humid climates with temperatures ranging from 60 to 85 degrees. This disease materializes as small circles, like silver dollars, appearing brown or straw-colored. To control this problem, water grass in the morning, increase soil nitrogen levels with a fertilizer containing a higher nitrogen ratio and use a thatcher to aerate the lawn. Fungicide is not required for controlling this disease.
Pythium Blight: Pythium Blight thrives in hot, humid climates manifesting as greasy or water-soaked spots. As the grass dies, it turns a light brown or tan before shriveling up with the eventual appearance of a white cottony fungus on the dead grass during periods of high moisture. John Swenson, North Dakota State University, recommends control of this disease by watering during the morning, but not excessively. Equally important is eliminating shaded areas, removing excess thatch and not over-fertilizing.
Slime Molds: Slime molds tend to appear on grass in wet, humid climates, especially after extended intervals of rain. They appear as white slime...