My Fall Grass Is Turning Yellow
- Rhizoctonia yellow patch is caused by a fungus called Rhizoctonia cerealis, according to North Dakota State University. Wet, cool weather conditions with temperatures between 50 to 65 degrees Fahrenheit during the months of October through April favor the germination and spread of fungal spores, according to the University of Minnesota. Gardeners may see symptoms of the disease clear up when the weather turns warm. The disease stops spreading when temperatures exceed 75 degrees Fahrenheit, yet lawn damage will remain apparent.
- Gardeners may notice yellow rings develop in the yard. The rings can extend a few inches to a few feet in diameter, according to the University of Minnesota. The morning is the best time to see the damage caused by rhizoctonia yellow patch, because a cob web like growth called mycelium is visible with dew. Left untreated, discolored yellow grass takes on a brown or light tan appearance, according to North Dakota State University. Leaf blades may turn red during severe yellow patch infection.
- A thick thatch layer, over 1/2 inch, greatly contributes to rhizoctonia yellow patch, according to North Dakota State University. Thick thatch layers between the soil and grass blades keep temperatures moist, which helps fungal spores germinate and spread. In addition, a thick thatch layer reduces the amount of air flow which benefits this lawn disease. To check your thatch layer, cut a 2-inch wedge piece of turf out of your lawn with a sharp knife. Use a power dethatcher to remove a thatch layer over 1/2 inch.
- Over watering your lawn is like throwing gas on the fire. Excessive soil moisture prevents fungal spores from drying out. Water your lawn when it receives less than one inch of water a week. To figure out if it has received an inch of water, place tuna cans in the yard. When the tuna can is half full, avoid watering for that week. If it is less than halfway full, supplement water. Avoid watering in the afternoon, or you can encourage the spread of the disease.