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

Recent research by Jim Brosnan, Ph.D. and his team at the University of Tennessee has uncovered an exciting new strategy to manage annual bluegrass (Poa annua) in bermudagrass tees, fairways and roughs – Trimmit^® 2SC plant growth regulator.

Trimmit 2SC has long been used in the spring and early summer to suppress annual bluegrass in creeping bentgrass putting greens. However, applications to bermudagrass at this time can dramatically slow bermudagrass green up. For this reason, it is generally not recommended to apply Trimmit 2SC to bermudagrass after March 15.

Instead of spring applications, Dr. Brosnan’s group has shown that late summer to fall applications of Trimmit 2SC significantly suppress annual bluegrass without negatively affecting bermudagrass green up the following spring. Specifically in the trial, three applications at 16 fl. oz./A were applied on a three-week interval beginning in late August and continuing through early October. These treatments provided 85% control of annual bluegrass through early March of the following year.

Suppression of annual bluegrass with Trimmit 2SC in bermudagrass

With widespread herbicide resistance in annual bluegrass populations, many golf course superintendents are struggling to adequately control this weed. Trimmit 2SC offers a valuable new option to which there is no known resistance.

Research is ongoing to optimize rates, intervals and timings. Pending those results, we recommend applying Trimmit 2SC:

• At 16 fl. oz./A during late summer to fall (typically August through October) when soil temperatures are between 60-75 ^°F and annual bluegrass germination is most active
• On a three- to four-week application interval
• With sufficient water (at least 40 gal./A) to ensure uniform coverage
• Irrigating within 24 hours to help the active ingredient penetrate the thatch and soil

For additional application and rate recommendations, download the new Poa Annua Suppression in Bermudagrass Turf with Trimmit 2SC information sheet.

Do not apply Trimmit 2SC to bermudagrass putting greens unless they are overseeded. Avoid use on residential lawns or athletic fields under heavy traffic. Refer to the Trimmit 2SC label for all other precautions and restrictions.

For more information visit GreenCastOnline.com/Trimmit2SC or contact your local Syngenta territory manager. 

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Performance assessments are based upon results or analysis of public information, field observations and/or internal Syngenta evaluations.

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