Photo by Eric B. Nelson, Cornell University
Click on image to enlarge.
Annual bluegrass (a
common weed in turf), Kentucky
Summer patch appears as circular yellow or tan areas of dead and
dying plants up to 1 foot (30 cm) in diameter. Healthy green plants
may remain in the center. Dark brown or black fungal hyphae develop
on roots, crowns, or stolons. Vascular discoloration may occur in
later stages of the disease.
Conditions favoring disease
High temperatures (85° to 95°F) in the late spring favor
the development of summer patch. The disease is most severe when
the turf is mowed low or when there is excessive soil moisture.
Prevention and management
Promote root growth by soil aeration and slow-release
nitrogen. Improve drainage, reduce compaction, control thatch,
and avoid drought stress. Follow irrigation
recommendations for your turf species. Mow at the higher end
of the recommended height range
for your species. Reduce your soil pH if it is higher than 7. A
professional soil analysis may
be necessary to determine which nutrients are lacking in your soil
and can provide you with information about what to add to your
soil to maintain an ideal soil pH.
For more information on lawn diseases, refer to:
Pest Notes: Lawn Diseases:
Prevention and Management