Large Patch Information
Causal Agent(s)
- Rhizoctonia solani AG2 2LP
Hosts
- Hybrid bermudagrass
- Zoysiagrass
- Centipedegrass
- St. Augustinegrass
- Seashore paspalum
Symptoms & Signs
Stand symptoms manifest as roughly circular patches ranging from a few inches to several feet in diameter. Turfgrass in the center of the patch may start to recover, leaving a ring-like appearance to patches. Patches are typically tan in color and may have an orange-red color on the perimeter. Individual plants may not have leaf lesions, but the sheaths of infected plants will become rotten, and leaves are easily pulled off plants with very little force.
Images of large patch symptoms:
When Does it Occur?
Infection occurs in the fall when soil temperatures stay below 70° F. However, symptoms do not typically manifest until spring as infected turfgrass emerges from dormancy. Large patch is favored by extended periods of cool, wet weather when turfgrass is not dormant.
Cultural Management
Reduce stress on turfgrass during favorable weather for large patch. Do not fertilize in the fall. A rule of thumb is not to apply nitrogen to warm-season turfgrasses within six weeks before dormancy. Promote drainage, relieve compaction, and remove excessive thatch.
Chemical Management
Large patch fungicides must be made preventatively. Fungicides should be applied when soil temperatures drop below 70° F for several consecutive days in the fall. Water-in with 1/8” irrigation immediately after application. Curative fungicide applications are not recommended in the spring.
