|Aascochyta Leaf Blight in Bluegrass|
Cool moist weather followed by hot dry weather often spells Ascochyta leaf blight on turf. The fungal disease kills leaf blades, creating irregular patches of straw colored turf. Fortunately, Ascochyta does not kill the crowns or roots of plants, so they will eventually recover within a couple of weeks.
To manage the disease, mow lawns 3 inches tall, making sure mower blades are sharp. (Dull mower blades create ragged tips on grass plants, providing the fungus more entry points.)
Keep the turf evenly moist. Check sprinkler heads to make sure they are working correctly, are not clogged, tipped or broken. It's better to water deeply and infrequently. Shallow watering encourages shallow rooting which makes plants more susceptible to drying out. Too much water in poorly drained soils can increase disease development. For more information about Ascochyta, see this CSU Extension fact sheet.