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Large patch, formerly known as brown patch, is a serious disease of turfgrass in Louisiana. The disease is caused by the soilborne fungus Rhizoctonia solani, and symptoms typically appear as large circular or irregular patches of yellow to brown turfgrass. The pathogen does not usually kill the grass but causes a rot at the base of the leaf sheaths, which results in the separation of leaves from the crown of the plant. Large patch develops rapidly under cooler temperatures and wet conditions and is most often observed in Louisiana during the spring and fall. St. Augustine grass, centipedegrass, bermudagrass, seashore paspalum, zoysiagrass and cool-season turfgrasses used for overseeding are susceptible to this disease.
Circular patches of large patch in St. Augustinegrass
Large patch in St. Augustinegrass lawn.
One way to reduce disease incidence and accelerate turfgrass recovery is to maintain a healthy lawn through balanced fertilization and irrigation and regular mowing. Follow these simple guidelines:
In addition to cultural practices, fungicide applications may be required to achieve effective disease control. Always check fungicides labels for site application restrictions. When selecting products, homeowners must purchase fungicides that are labelled and recommended for residential lawns. When using fungicides, always remember to follow the label rates and frequency of application.
Fungicides used to manage large patch are sold under various trade names. They contain these active ingredients.
| Fungicide Active Ingredients |
| azoxystrobin |
| captan |
| maneb |
| mancozeb |
| myclobutanil |
| propiconazole |
| tebiconazole |
| thiophanate-methyl |
For information on sample collection and submission guidelines please visit the Plant Diagnostic Center.
Download here: Louisiana Home Lawn Series: 3624-Y
