Distant: Holes on greens and tees, and, ball-mark damage where the larger cutworms scalp the turf in a small circle around the entrance to their tunnel.
Up close: Pencil-sized holes on greens of tees that have been enlarged. Sometimes a problem on fairways, too.(Image C)
When damage would be found: June to October
Host: Bentgrass, annual bluegrass
Site: Highly maintained golf course turf. Irrigated tees and greens.
Description of damaging stage: The larval stages are the damaging stages and are 1/2 to 1 3/4 inch long caterpillars. These have a distinct head capsule with chewing mouthparts, 6 legs, and most of the segments following with fleshy prolegs. (Image D)
Sampling: Use a disclosing solution consisting of 1 oz of liquid detergent in 3 gal of water and pour over the green. In approximately 3-5 min the larvae will come to the top of the grass and will be very evident. Also, look for emergence holes from cutworm tunnels on tees and greens. Cutworms will often chew the stems of grass plants around the entrance to their tunnel, leaving a yellow ball-mark patch.
Preventing Pest Injury to Turfgrass: Home lawns, recreational turf and golf course roughs can be managed to avoid insect injury without insecticides by using proper fertility, mowing at a height of 3.0 to 4.0 inches, and watering during dry periods. This will build a dense stand of turf and a diverse community of insects that will keep turf pests under control. All lawns in Michigan will typically start off lush and green in the spring and will go dormant and turn brown during periods of little rain. Information on the use of insecticides to treat turf pest problems is only meant to be used for the unusual cases where turf damage from pests becomes unacceptable. Even then, insecticides should only be used in areas of a lawn with severe turf damage, and only until a dense turf is re-established.
Using insecticides: Use insecticides judiciously, temporarily, and only in response to unacceptable turf injury. Many insecticides are poisonous if ingested, and therefore must be stored in places where they cannot be found by children. Use the rate recommended on the label for the pest you are attempting to control. Wear rubber gloves, safety glasses (or goggles), rubber boots, long pants and long sleeved shirts when mixing and applying insecticides. The most caution is needed when mixing a concentrated insecticide in water, because skin contact with the concentrated insecticide in the original container is more dangerous than contact with the diluted insecticide after mixing. Water the turf immediately after applying the insecticide to wash it to the base of the plants or into the soil and allow the turf to dry before allowing access by people and pets.
Chemical Control of Cutworm: 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.