Large Patch on St. Augustinegrass

Large patch (Rhizoctonia solani) is a disease seen mainly on warm season grasses such as zoysiagrass (Zoysia spp.) centipedegrass (Eremochloa ophiuroides) and St Augustinegrass (Stentotaphrum secundatum). Rhizoctonia species are classified in the group of basidiomycetes and are considered as faculitative parasites. Large irregular shaped patches ranging from 0.5 meters to 3 meters in diameter. A yellow to bright orange ring may be noted on the edge of the patches while internally the patch may be sunken and brown (Picture 1). Turfgrass affected may be easily pulled from the sheath and the base of the shoot may look water soaked. Large patch is active when soil temperatures increase above 65 °F in Autumn and can be a problem through spring time. Management practices that may reduce the problem include reducing thatch and soil compaction to aid water movement. Additionally increases in shading may lead to problems and thus removal of tree lines or thinning of branches will help. Increasing the height of cut on turfgrasses may also be of help. Reducing excessive nitrogen applications is also considered to be a beneficial practice.

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