Updated large patch program brings new options and added flexibility

By Lane Tredway, Ph.D., technical services manager, Syngenta

Large patch prevention is critical to maintenance of high-quality zoysiagrass turf on the golf course. All zoysiagrass varieties are prone to the disease, which strikes during cool, wet weather from late summer through spring. Any breakthrough during this time will likely linger for weeks or months as cool temperatures and short days suppress zoysiagrass growth.





The GreenTrust® 365 Large Patch Assurance Prevention Assurance includes powerful innovations in large patch control to provide unmatched performance and flexibility. Depending on geographical region, the updated program includes expanded product options, extended application intervals and fewer applications to deliver guaranteed results.

Ascernity® fungicide (1 fl. oz./1,000 ft.2) is the top recommendation in all regions, as it is the most active and longest-lasting product available for large patch control, providing up to 42 days of protection according to a 2(ee) recommendation recently approved by most states. Superintendents in California and the southeastern U.S. can expand the interval between fall applications from four to six weeks. In the Midwest, a single fall application is sufficient with the extended protection provided by Ascernity.





Source: Dr. Mike Richardson, University of Arkansas, 2015. Study performed on Cavalier zoysia matrella greens, 2014-2015. Three applications were made on Sept. 23, Oct. 20 and April 9, 2015. 

In the southeastern U.S., Posterity® XT fungicide (2.25 fl. oz./1,000 ft.2) is an alternative to Ascernity for locations where spring dead spot or fairy ring are a significant concern. For best control of both large patch and spring dead spot, Posterity XT should be applied twice in the fall on a four-week interval. 

Even with the right products, proper application timing is important to achieve optimal large patch control. Preventive fungicide applications should be initiated in late summer to fall when soil temperatures dip below 68 F. Spring applications should be made when soil temperatures are above 55 F and the zoysiagrass is at least 50% green.

To track soil temperatures in your area and receive email alerts when the target threshold is reached, sign up for soil temperature alerts.


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

Performance assessments are based upon results or analysis of public information, field observations and/or internal Syngenta evaluations. Trials reflect treatment rates commonly recommended in the marketplace.


Syngenta hereby disclaims any liability for third-party websites referenced herein.

© 2021 Syngenta. Important: Always read and follow label instructions. Some products may not be registered for sale or use in all states or counties and/or may have state-specific use requirements. Please check with your local extension service to ensure registration and proper use. Ascernity®, GreenCast®, GreenTrust®, Headway®, SOLATENOL®,  the Alliance Frame, the Purpose icon and the Syngenta logo are trademarks of a Syngenta Group Company.

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