Turfgrass Insect Control
Turfgrass Insect Control
There are only a few insects that damage turfgrass in northern Utah. Most of them can be prevented or their numbers decreased by maintaining a healthy vigorous lawn according to Jerry Goodspeed, USU Extension, Weber County.
DIAGNOSING INSECT DAMAGE
Although each lawn and turf area may look a little different when attacked by insects, there are some common diagnostic symptoms. Look for one or more of the following symptoms to determine if a lawn problem is insect related. The lawn appears brown, drought-stressed, and does not recover when watered. The affected area pulls up easily, and may roll up like a piece of sod. Birds and other small animals feed in the lawn area. The damage is most prevalent during the warmer, summer months.
IDENTIFICATION OF SPECIFIC INSECTS
Three main families of insects attack lawns in northern Utah. Each is slightly different in appearance and shape. To improve control it is important to identify the specific insect causing the damage. The larva stage of these insects do most of the damage.
White Grubs: The larva or juvenile rolls into a ‘C’ shape when disturbed. They can be from ½ to 1 inch long. The larva is cream-colored with a brown to light-red colored head. They have three pairs of legs. The adult is a scarab beetle.
Billbugs: The larva or juvenile rolls into a ‘C’ shape when disturbed. The larva is about ¼ inch long. The larva is cream-colored with a light-brown to orange colored head. Adults are ½-inch long, black beetles with a distinctive, long shaped snout. The adults can be seen walking across driveways or sideways adjacent to turf areas.
Sod Webworm: The larva or juvenile stage is brown to cream colored. The larva is about ½-inch long. The worms can often be seen in the grass blades, and webbing may be present. The adults are a gray, nondescript moth that flies in the evening.
The most important insect control method is to keep the turf area as healthy as possible. However, if a problem does occur, there are different options for controlling lawn insects.
Nematodes: Beneficial nematodes that attack lawn-eating insects are available in a number of products on the market. Nematodes have shown varied results. They must be bought fresh and reapplied to the area annually (if not more often).
Bacillus thuringiensis (Bt): This common, soil-living bacteria is somewhat effective on webworms, but shows very limited results on white grubs and billbugs. Sold under many different brand names, it must be reapplied every five to seven days for maximum effectiveness.
Insecticides: There are a number of insecticides on the market. Some work better as a preventative (before the problem), while others are designed as curative (after the fact). Each has specific instructions regarding application, watering, and timing of re-applications. Read and follow all label directions for safe use and best results. The following are some but not all of the recommended products (common brand names are in parenthesis):
PREVENTATIVE--Best when applied before or right after egg hatch: HALEFENOZIDE (Grub X): Can be applied in granular form or as a liquid. IMIDACLOPRID (Merit): Provides season long control. Works well on white grubs and billbugs. Best applied to areas with a history of problems.
CURATIVE--Best when applied before or right after egg hatch: CARBARYL (Sevin): Can be harmful to earthworms and other beneficial insects. Applied in a granular or liquid form.
TRICHLORFON (Dylox): Can be applied as a granular or wettable powder. Good at penetrating through thatch.