Necrotic Ring Spot (Leptosphaeria korrae) & Summer Patch (Phialophera graminicola)
They may cause a recurring problem which scars the turf, leaving unattractive areas in the lawn. Both diseases cause somewhat circular patches of dead grass with a spot of living turf in the center, giving a "frogeye" or "doughnut-shaped" look.
Signs and Symptoms:
Typically, scattered light green patches about 2" to 6" in
diameter appear. These patches enlarge and then rapidly fade to reddish-brown
and, finally, a straw color. Healthy grass in the center gives the "frog-eye"
appearance. Serious damage occurs when rings are numerous and overlap.
They may also increase in size for several years.
Necrotic ring spot - This disease is particularly damaging to Kentucky bluegrass sod, which is two to four years old. Shaded areas of lawns are especially vulnerable. Symptoms become more evident following a hot, dry period.
Summer patch - This disease is primarily associated with established Kentucky bluegrass growing in full sunlight. Summer patch occurs during periods of sustained high temperatures, which follow periods of ample moisture. Symptoms will become more evident following hot, dry conditions.
Pro Care Practices for Control:A Pro Care application of Rubigan is available for the control of this disease. Treatment must be made in April or May of that growing season.
Proper fertilization and sulfur is vital for the lawn. Several of Pro Care's seasonal fertilizations contain sulfur, which is beneficial to lawns with necrotic ring spot or summer patch.
Aeration will remove excessive thatch which harbors fungi.
Cultural Practices for Control:Provide proper watering practices to keep the lawn from going into a stressful condition or into dormancy. Maintain adequate moisture on south- and west-facing sunny slopes and lawn areas next to sidewalks or driveways which dry out faster and have higher soil temperatures than other lawn areas. Use soaker hoses or cycle sprinkler systems to avoid run-off. Water early in the morning so that the lawn will dry before dusk.
Maintain a mowing height of 2" to 3" and remove no more then 1/3 of the leaf blade at a mowing.
Select sod from a quality grower who plants lawn gross varieties, which are resistant to necrotic ring spot and summer patch.
Overseed scarred areas with seeds which are resistant to these diseases.
The Pro-Care staff is always ready to assist you with your lawn. Please call if we may provide any information to enhance your lawn's health or appearance.