What Causes Dying, Black Grass

Stripe Smut

• Stripe smut infects lawns when temperatures are between 50 to 60 degrees Fahrenheit, according to North Dakota State University. Because stripe smut germinates and spreads during cool temperatures, the disease generally infects cool-season grass types like bluegrasses or fescues. The spores spread through wind, rainwater runoff, animals and feet, according to Cornell University research. Stripe smut fungal spores survive hot and cold temperatures on grass blades, according to Cornell University. When temperatures cool, stripe smut symptoms become evident.

Symptoms

• Grass infected with stripe smut exhibits symptoms such as elongated black streaks in the blades, according to North Dakota State University. Once these streaks turn black, they burst open and fungal spores spill out of the grass blades. Other symptoms of stripe smut include ribbony grass, thinning lawn areas and dying grass blades. When left untreated, stripe smut causes bare or dead patches of grass areas. Bare lawn areas are the perfect breeding ground for weed growth.

Cultural Control

• Proper fertilization and water may contain stripe smut and help your grass recover from the disease. When fertilizing diseased grass, use a balanced fertilizer, as suggested by Cornell University. You can use a fertilizer that has a NPK amount of 10-10-10 on your grass at a rate of 1 lb. of nitrogen per 1,000 square feet. Keep your grass watered with 1 inch of water per week. Apply water in the late afternoon or morning, as suggested by North Dakota State University.

Chemical Control

• Severely infected lawns may need fungicide treatments, according to Cornell University. Gardeners should apply fungicides right before their grass goes dormant in the fall and in the early spring. For example, the best time to apply fungicides to control stripe smut in New York is in November and March, according to Cornell University. Drench the soil with fungicide so that the first 1/2 to 1 inch layer of topsoil absorbs it.