Causal Agent:
Gaeumannomyces graminis var. avenae
Susceptible Turfgrasses:
Colonial bentgrass
Creeping bentgrass
Identification:
Early Symptoms:
Small, circular reddish-brown spots appear.
Patch Development:
Spots progress to wilted, circular patches with blue-gray, red-brown, or bronze coloring.
In advanced stages, patches can measure several feet (up to 1.5 meters) in diameter.
Chronic Symptoms:
As bentgrass ages, patches may appear yellow, indicating take-all decline.
Favorable Conditions:
Root Infection:
Develops in cool, wet weather and worsens with heat stress in rapidly drying soils.
Sand-Based Rootzones:
Common in new sand-based rootzones with pH levels greater than 6.5.
Typically emerges in the second year post-establishment and decreases over 2 to 5 years.
Persistent Cases:
Can occur on older sites with abnormal rainfall, particularly in late winter and spring. However, rarely persists as a chronic issue, particularly with abnormally high rainfall.
Management Tips:
pH Adjustment:
Maintain rootzone pH levels below 6.5.
Soil Drainage:
Improve soil drainage to reduce excess moisture in affected areas.
Preventive Fungicide Applications:
Apply systemic fungicides in early spring or late fall for effective control.
Aerification:
Regular aerification to alleviate soil compaction and enhance water movement.
Irrigation Practices:
Avoid over-irrigation; instead, maintain consistent, light watering schedules to minimize heat stress.
