Leaf spot / melting out
Drechslera and Bipolaris spp.
A Helminthosporium complex causing leaf lesions then crown/root rot (melting out) and stand thinning.
Identification
Purple-brown lesions with tan centers on leaves; in the melting-out phase crowns and roots rot, causing severe thinning and dieback.
Symptoms
Purplish lesions with tan centers. General thinning and dieback (melting out). Rotted crowns/roots in advanced cases
Signs
Purple-brown lesions with tan centers on leaves; in the melting-out phase crowns and roots rot, causing severe thinning and dieback.
Biology
Leaf spot and melting out are caused by Drechslera and Bipolaris species. These fungi initially infect leaf blades and may later move into crowns and roots, causing the melting-out phase and more severe stand thinning.
Epidemiology
Cool wet spring (leaf phase), then heat/stress for melting out; low mowing and excess nitrogen worsen it.
Favorable Conditions
Cool wet spring (leaf phase), then heat/stress for melting out; low mowing and excess nitrogen worsen it.
Cultural Management
Raise mowing height; avoid excess spring nitrogen. Use resistant cultivars; reduce leaf wetness
Further Reading
University extension resources — open in a new tab.
Related Reports
No published reports yet for this pest.
Reports will appear here as they are peer-reviewed and published.