Featured Article | GreenCast | Syngenta

Now is the time to plan for large patch

By Lane Tredway, technical services manager for Syngenta

In the Southern and Midwestern United States, periods of cool, wet weather in late summer and fall can prompt large patch outbreaks on warm-season grasses. Zoysiagrass, centipedegrass and St. Augustinegrass are particularly susceptible to this disease, but bermudagrass can be affected as well.

Because large patch attacks when warm-season grasses are growing slowly and preparing for dormancy, its symptoms can linger until the following spring when growth resumes. Large patch weather tends to sneak up in late summer to early fall, so it pays to have a preventive plan in place to ensure applications are ready to go when needed.

Product selection for large patch prevention
Selecting an effective product is an important first step for large patch management. While many products will control R. solani, few provide the residual control needed to protect warm-season grasses through the fall, winter and spring. Velista®, Headway® and Heritage® fungicides provide excellent control of large patch. Granular formulations, like 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 can offer effective large patch control.

Fungicide Preventive Applications
Rate
Interval
Velista0.5 to 0.7 oz./1,000 ft.214-28 days
Headway1.5 to 3 fl. oz./1,000 ft.214-28 days
Heritage 50WG0.2 to 0.4 oz./1,000 ft.214-28 days
Heritage G2 to 4 lb./1,000 ft.214-28 days
Headway G2 to 4 lb./1,000 ft.214-28 days
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Favorable environmental conditionsn

Effective prevention is essential when it comes to large patch, since the pathogen attacks when the turf is not growing optimally. For enhanced efficacy, timing should be based on soil temperature thresholds rather than calendar date. Pathogen activity begins in the late summer or early fall when soil temperatures dip below 70° F, and continues into the spring as long as soil temperatures are between 50° F and 70° F.

To help you get the right timing for large patch prevention in your area, Syngenta has soil temperature maps and alerts available for soil-borne diseases like large patch, spring dead spot and more. You can view current and historical soil temperature data, and sign up to receive email alerts when temperatures become favorable in your location.

Source: Syngenta, 2007.

For more information about large patch control, contact your local Syngenta territory manager.

All photos are either the property of Syngenta or are used with permission.

©2019 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 and proper use. Headway®, Heritage®, Velista® and the Syngenta logo are trademarks of a Syngenta Group Company.