By Matt Giese, M.S., technical services manager, Syngenta

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The turfgrass ant (Lasius neoniger) is a major nuisance pest on golf courses across much of the U.S. This ant is especially problematic on golf putting greens where it builds volcano-shaped mounds that are 2-4 in. in diameter. The mounds disrupt ball roll, while the excavated soil smothers the closely mowed turf canopy. The soil and sand in these mounds can also rapidly dull mower blades.

These ants live and work in interconnected burrows and chambers that are 10-15 in. deep in the soil. As they build different nest entrances, mounds are formed from the material the ants bring to the surface. The number of mounds can increase significantly during early spring to midsummer as the colony grows. Timing applications when colonies are small, weak and food sources are limited — typically early spring and late fall — tends to have greater success for colony collapse.

Research indicates Meridian^® 25WG insecticide can provide measured control of ants for up to eight to 12 weeks. For faster knockdown, a fast-acting pyrethroid like Scimitar^® GC insecticide can be applied to kill worker ants when mounds first appear. These treatments can provide mound suppression for two to three weeks, but usually fail to eliminate the queen in her underground chamber. For immediate knockdown and long-term control, Meridian 25WG may be tank-mixed in an ant control program with Scimitar GC.

Since nesting areas may not be located on greens or tees, applications should include treatment of up to 30 ft. of turf surrounding these surfaces. Treatment considerations should also be given to fairways, roughs, approaches and collars, as these are popular nesting areas.

You can read more about turfgrass ant mound concentration on golf course in Golf Course Management Magazine’s article on turfgrass ants.

Recommendations

• Time applications when colonies are small/weakened and food sources are limited (early spring and late fall) as this tends to have greater success rates of colony collapse and control.
• Treat the playing surface (e.g. tee, green or fairway) and outside the affected area well off the playing surface and into the rough as mounds found on short-cut turf are often satellite (sub-nest) mounds created by the worker ants of the colonies.

Managing turfgrass ants

• Scimitar GC and Meridian 25WG
  • Rate: 10 fl. oz. of Scimitar GC per acre + 17 oz. Meridian 25WG per acre
  • Timing: apply when mounds are first observed
  • Combining Scimitar GC and Meridian 25WG offers immediate knockdown and long-term control of ants and white grubs
  • Proper treatment should include satellite mounds approximately 30 ft. outside of the target site
    • Spray volume: 65 gal. per acre
  • Application should be watered in once spray solution has dried on the foliage
  • Can provide control up to eight to 12 weeks depending on timing and soil type
    • Gradual control — may take as long as four weeks to see results when using only Meridian 25WG

Table 1a. Season-long efficacy of golf course fairway ant mounds

WAT= Weeks After Treatment. Ohio State University, 2000.

Table 1b. Season-long efficacy of golf course fairway ant mounds

WAT= Weeks After Treatment. Ohio State University, 2000.

Table 2. Ant control on a golf course fairway

DAT= Days after treatment. University of Wisconsin, 2007.

Table 3a. Ant control on a golf course fairway

DAT= Days After Treatment. University of Nebraska, 2007.

Table 3b. Ant control on a golf course fairway

DAT= Days After Treatment. University of Nebraska, 2007.

For more information about managing turfgrass ants, contact your local Syngenta territory manager or download the Meridian sell sheet.

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.

© 2023 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. Scimitar GC is a Restricted Use Pesticide. Meridian ^®, Scimitar^® and the Syngenta logo are trademarks of a Syngenta Group Company. All other trademarks used herein are the property of their respective third-party owners.