2016 has already been a difficult year for managing diseases, including dollar spot (Sclerotinia homoeocarpa). This disease is most active during periods of prolonged high humidity, meaning the warm days and cool, humid nights of autumn can trigger an outbreak of dollar spot.

The key to fall dollar spot control is to plan fungicide applications, make them when needed and use the proper water-carrier volume and nozzles. Secure^® and Velista^® fungicides are great options to help control dollar spot this fall. Secure provides the protection of a multi-site contact fungicide, while Velista delivers systemic control.

Figure 1 – Dollar spot control on greens

Latin, Purdue University. 14-day spray interval. 2015.

It is critical to select the proper spray nozzle and water volume to achieve optimal disease control. Table 1 demonstrates that an air induction nozzle and an XRC flat fan nozzle, each of which provide a medium-to-coarse spray droplet, provided better dollar spot control than other nozzle types. The best numerical dollar spot control was achieved with an air induction nozzle and a 2-gallon water-carrier volume.

Table 1 - Dollar spot control with Velista as influenced by rate, spray interval, nozzle type and water-carrier volume

Fidanza, Penn State University. Reading, Pennsylvania, 2015.

• ¹14-day spray interval last applied on September 14, 2015. 21-day spray interval last sprayed on September 8, 2015.
• ²Nozzle types and water droplet size:
• TurfJet nozzle is an extremely coarse spray droplet (428 to 622 microns in diameter).
• Air induction nozzle is a very coarse spray droplet (349 to 428 microns in diameter).
• XRC nozzle is a medium spray droplet (177 to 218 microns in diameter).
• ³Data was collected on September 30, 2015.

Utilizing plant growth regulators (PGRs) like Primo Maxx^® and Trimmit^® 2SC can help slow the growth of the plant, thus preventing removal of dollar spot protection through mowing. This is especially important in the fall, as the clipping production of cool-season grasses will naturally increase with cooler weather.

To learn more about fall dollar spot control, contact your local Syngenta territory manager.

©2016 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. Primo Maxx^®, Trimmit^®, Velista^® and the Syngenta logo are trademarks of a Syngenta Group Company. Secure^® is a registered trademark of Ishihara Sangyo Kaisha, LTD. All other trademarks used herein are the property of their respective company.