Leaf Spots and a Melted Out Lawn

Leaf Spot

• Leaf spot is not a rare occurrence and is one of the most destructive fungal diseases for grass types such as bluegrass, according to North Dakota State University. This disease is caused by bipolaris sorokiniana fungal spores. Lawns that have a thick thatch layer, have been over-fertilized or mowed too low are the most susceptible to the leaf spot. Your lawn is most likely to contract the disease during hot weather conditions.

Damage

• Gardeners may notice their grass blades turning purplish-red to purplish-brown around the edges, according to North Dakota State University. The center of infected grass is typically tan. Grass tips left untreated may eventually die out, which is called blighting. You may still treat the grass at this stage with fungicide if the disease has not moved down to the root system of the plant or melt out. Diseased grass in the spring will worsen by summer when the disease is most active, according to the University of Rhode Island.

Treatment

• Leaf spot may be treated with fungicide as long as the entire surface of the grass blade is thoroughly covered. Gardeners should apply fungicide every five to 10 days depending on how often they water or mow. Prevent leaf spot from occurring by mowing at the proper grass height. Refrain from taking off more than 1/3 of the grass blade when mowing. Water in the morning. Wet grass blades and nighttime temperatures promote leaf spot.

Melting Out

• Melting out occurs when drechslera poae fungal spores infect the roots and crowns of grass. Generally, melting out occurs in patches that can be from several inches to many feet in diameter, according to North Dakota State University. You may notice rotted grass in these areas. Melting out areas or parts of the yard that have completely died should be dug up and reseeded. Monitor the reseeded area for leaf spot. Take preventative measures to ensure that your new grass seedlings do not contract leaf spot.