Ataenius and Cutworms Active on Golf Courses

Dr. David Smitley, Terry Davis, and Dr. Kevin W. Frank

Michigan State University

In the last week both Ataenius grubs (Ataenius Spretulus) and cutworms (Agrotis Ipsilon) have been observed feeding in Poa annua and creeping bentgrass putting greens.  Ataenius grubs have been found causing significant injury on Poa annua greens that have recently recovered from winterkill.  Due to the rather short root system of recovering Poa, it appears in some area the Ataenius grubs are causing injury at lower than normal thresholds.  The typical threshold for recommending a curative insecticide application is 40 grubs/ft.².   For curative insecticide applications use carbaryl or triclorfon.  These insecticides need to be applied at the full application rate and watered in with ½ inch of water following application.  Additional information on Ataenius can be found at http://msuturfinsects.net/details/_/ataenius_and_aphodius_6/

 

Ataenius grubs.

Turf easily peeled back from grub feeding.

Skunk and bird damage from feeding on grubs.

Cutworms are also active on putting greens.  Damage looks similar to an unrepaired ball mark.  Cutworms will often chew the stems of grass plants around the entrance to their tunnel, leaving a yellow ‘ball-mark’ patch.  A “disclosing solution” consisting of 1 oz of liquid detergent in 3 gal of water can be poured over suspected infestations to force the cutworms to the surface.  In approximately 3-5 min the larvae will come to the surface and will be very evident. Synthetic pyrethroid insecticides such as deltamethrin, cyfluthrin, bifenthrin, permethrin and lambda-cyhalothrin will work very well to reduce damage from cutworms. Safe alternative products include Bt (Bacillus thuringiensis) and insect parasitic nematodes. Any insecticide applied to tees, greens or fairways may need to be reapplied every two weeks during periods of maximum cutworm moth activity, because most of the insecticide residue is removed daily or every other day with the clippings.  Additional information on cutworms can be found at http://msuturfinsects.net/details/_/cutworm_10/

Black cutworm on putting green.