Integrated Pest Management

Ascochyta Leaf Blight

Ascochyta sp.


Ascochyta leaf blight (Ned Tisserat, Colorado State University,


Ascochyta leaf blight symptom (Iowa State University Extension)


Hosts, Symptoms & Signs

  • affects all species of grass
  • leaves die back from the tip, resulting in brown patches of grass
  • does not cause permanent damage
  • symptoms can occur at any time but are more commonly seen during hot, dry weather
  • top third of leaf blade dies back, and the area between diseased and healthy tissue is slightly constricted
  • fruiting structures develop on dead grass blades

Disease Cycle

  • overwinters in plant debris and thatch
  • spores are released from fruiting structures during wet weather and are dispersed by splashing water and lawn mowers
  • infections occur on the newly cut end of the grass blade

IPM Recommendations

  • Reduce thatch with proper cultural practices.
  • Improve water penetration by aerification.
  • Maintain sharp mower blades to reduce wounding of grass; reduce mowing frequency during an outbreak.
  • Implement a balanced fertilizer program; avoid excessive nitrogen, especially in the spring.
  • Avoid drought stress as well as excessive irrigation.