It’s not too early to plan for large patch

IT'S NOT TOO EARLY TO PREVENT LARGE PATCH

In the Southern and Midwestern United States, periods of cool and wet weather can prompt symptoms of large patch from late summer through spring. Large patch is caused by a strain of Rhizoctonia solani that chronically affects warm-season grasses including zoysiagrass, centipedegrass, and St. Augustinegrass. Patches caused by the appropriately named disease expand between three to ten feet in diameter.

R. solani survives in the thatch and in areas of past infection. Since large patch commonly appears in the same locations each year, golf course superintendents should aim to prevent the disease early with the appropriate fungicide applications.

Favorable environmental conditions

Large patch begins developing when soil temperatures decline to 68° F in the late summer or early fall. Extended periods of cloudy, wet weather can rapidly accelerate infection and symptom development. The basal portions of turfgrass are first affected and will turn leaf sheaths a reddish-brown color. Over time, the disease appears as yellow-orange, blighted and irregular patches. When the disease is actively developing, the outer perimeter of the patches often have a pronounced red or orange color.


Effective prevention is essential when it comes to large patch, since the pathogen is attacking at a time when the turf is not growing optimally. For enhanced efficacy, application timing should be based on soil temperature thresholds rather than days on the calendar. Pathogen activity begins in the late summer or early fall when soil temperatures decline to 68° F, and continues into the spring as long as soil temperatures are between 40° F and 68° F. 

Product selection for large patch prevention

Selecting an effective product is just as important as proper application timing. While many products will control R. solani, few provide the residual control needed to protect the warm-season grasses through the fall, winter and spring. Velista^®, Headway^® and Heritage Action™ fungicides provide excellent control of large patch. The granular formulations, Headway G and Heritage^® G fungicides, are ideal for both broadcast and spot applications.

In general, making two applications in the fall and one application in the spring with any of the following fungicides will offer effective large patch control.

©2016 Syngenta. Important: Always read and follow label instructions. Some products may not be registered for sale or use in all states or counties. Please check with your local extension service to ensure registration status. Headway^®, Heritage^®, Heritage Action™, Velista^® and the Syngenta logo are trademarks of a Syngenta Group Company.