06/11/2026
Ascochyta leaf spot symptoms may develop throughout the growing season but are more common during hot, droughty periods that were preceded by cool, rainy conditions.
Large irregular patches of turf rapidly turn a straw-color and appear dead. The overall appearance of the disease may resemble drought stress. If you're watering and some areas are green while adjacent areas are straw-colored, it might be Ascochyta leaf blight.
This is a common disease of Kentucky bluegrass, and occasionally tall fescue and perennial ryegrass during the summer. The disease causes large, irregularly shaped, straw-colored patches to develop rapidly.
Because the Ascochyta fungus is primarily a foliar pathogen, diseased grass usually recovers relatively quickly. Environmental conditions that trigger Ascochyta leaf blight are poorly understood.
Management:
-Reduce mowing frequency (skip mowing in affected areas) and bag clippings if possible as the fungus can spread from one location to another on clippings.
-Maintain height of cut between 3 and 4 inches, keep blades SHARP.
-Avoid mowing during wet weather especially when the disease is active.
-Try to maintain uniform soil moisture and water early/mid-afternoon.
-Maintain balanced fertility (Pure Turf's responsibility).
For more information, please contact us at 248-321-2991 or visit: https://extension.missouri.edu/programs/turfgrass-science/turfgrass-disease-profiles/ascochyta-leaf-blight
