Powdery mildew is primarily a problem on Kentucky bluegrass turf growing
in partial shade or in areas with poor air circulation. The disease is most
often found in the spring and fall when days are cloudy and nights are cool
and damp.
Symptoms. The disease appears as a white to light gray powdery growth
on the upper surfaces of leaves and leaf sheaths. It spreads rapidly in
shaded areas and the powdery growth becomes increasingly dense. The lower
leaves of Kentucky bluegrass may be completely covered by the powdery growth.
Infected leaves turn yellow, become tan or light brown and gradually shrivel
and die.
Repeated infestations of the disease results in greatly reduced growth and
eventual death of plants. Surviving plants often remain in a weakened condition.
Control. Reduced shading and increased air circulation will help
control powdery mildew. Where these conditions cannot be changed, fungicides
are available for control. Acti-dione RZ, Banner and Bayleton are fungicides
labeled for control of powdery mildew.