What is Leaf Blight? Why is my grass turning brown starting from the top?

LEAF BLIGHT – Ascochyta spp.

Leaf Blight occurs on lawns during hot humid weather. The disease enters the grass plants after evening mowing, followed by excessive night watering. In heavily infested patches the fungus damages the lawn in circular or tubular patches that often form large bleached areas. Close inspection of the plant reveals individual leaves dying from the tip down with a brownish purple line running horizontally across the plant. Control of these common lawn diseases The best method of control is for the homeowner to alter the present lawncare practices. Avoid allowing water to sit on the grass overnight. Avoid mowing in the evening. Prune trees to encourage more air movement. Also keeping the thatch layer to less than ½” (1 cm) and proper fertility should be done to prevent the occurrence of these diseases. Promoting a healthy lawn is the key. Have your Weed Man advise you on correct lawn maintenance.http://minneapolis.weedmanusa.com