Summer Turf Pests

By Leslie McGuire, managing editor

There?EUR??,,????'???s more than one way to skin a cat, and so it naturally follows there?EUR??,,????'???s more than one way to kill a bug. There are chemical pesticides, organic pesticides, ?EUR??,,????'??cultural?EUR??,,????'?? methods, biological controls and integrated pest management (IPM) programs.

Before you start any treatment methods, however, you need a diagnosis of which pest is the problem. The symptoms are often more obvious than the insects themselves. Identifying their feeding sites is the first step in determining which pests you?EUR??,,????'???re dealing with and how to treat them.

Left and right top: Cicadas emerge by burrowing up, leaving holes in the turf around trees. Cicadas emerge every 13 to 17 years. Their nymphs eat roots. Left and right bottom: Billbug adults eat small holes in blades of grass leaving yellow edges. Grass damaged by billbug larvae pulls up easily, so dig around roots to determine if larvae are present.

• Root feeders: These insects prune off roots below the surface or withdraw root fluids and cause the turf to turn yellow or brown, or stunt its growth. Root feeders include grubs, billbugs and pearl scales.
• Leaf and/or stem feeders: These insects have chewing mouthparts and consume leaf tissue or cut off growing shoots. Signs include turf that thins out and has bare spots. Sod webworms, cutworms and armyworms are the culprits here.
• Sap feeders: These insects with piercing/sucking mouthparts remove plant juices from above ground stems and leaves. Symptoms include plants that turn yellow, white or brown and may either wilt or grow abnormally. Leafhoppers, chinch bugs and mites can take credit for these problems.
• Nuisances: These insects are using turf as a home but are not actually feeding on the plants. They cause tunnels, piles of soil and may sting or bite. Earwigs, springtails, sowbugs, ants, green June beetles and mole crickets are the perpetrators here.

Other nuisance insects that burrow are cicadas. Cicada nymphs stay underground feeding on roots until they surface after 13 to 17 years through numerous emergence holes. Green June beetles are associated with mounds or holes in the soil or irregular yellow or brown patches of turf with small dirt mounds resembling anthills. Spittlebugs, true to their name, leave the grass yellow and dried out with white, frothy ?EUR??,,????'??spittle?EUR??,,????'?? apparent.

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Cultural Controls

According to University of California, Davis?EUR??,,????'??? IPM program, turf damage usually begins in small, scattered patches. However, poor cultural care and use of grass species that aren?EUR??,,????'???t right for the location is often the cause of unhealthy or dying lawns. Disease causing pathogens, overuse of chemical fertilizers, fungicides and herbicides, as well as dog urine produce damage that resembles that done by insects. Make sure there isn?EUR??,,????'???t some cultural control that will take care of the problem first.

Good cultural practices are the first step in correctly managing turf. Irrigating and fertilizing have a major impact on turf health. Physical controls such as thatch removal, choice of mowing height and frequency of mowing are very important.

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Appropriate fertilizing encourages a dense, thick lawn that allows grass to tolerate some insect pests without much damage. Fertilizer choice is very important since over-fertilizing can, in itself, cause damage to turf. Organic-Gro, made by regenerated Resources LLC, is a nontoxic fertilizer that bonds with the soil so that it retains the nutrients rather than losing them to runoff. If turfgrass is under stress and pesticide is applied, there is a greater chance it will suffer phytotoxic damage from the pesticide in addition to the damage already incurred from the insect pests. Insecticides should not be applied unless a pest is identified and doing severe damage. Great care should be used if applying toxic pesticides to turf that is accessible to children and pets.

Subsurface injection of water protects mole cricket-eating nematodes from ultraviolet light.

If the cultural methods and physical practices aren?EUR??,,????'???t working, then choose the least toxic pesticide whenever possible. Diazinon has been banned, and is a source of pollution. Other broad-spectrum insecticides and many pesticides pose risks to the beneficial and non-target organisms. They should only be used when the less toxic insecticides can?EUR??,,????'???t control the infestation.

Test Methods

Drench Test: To detect chinch bugs, adult billbugs and caterpillars including armyworms, cutworms and the larvae of lawn moths (sod webworms) mix one to two fluid ounces ( two to four tablespoons) of dishwashing liquid to a gallon of water. Apply the solution to a square yard of lawn as evenly as possible including both healthy and unhealthy grass. The drench will cause the insects to move to the surface. During the next 10 minutes identify and count the insects.

IPM programs rely on cultural, biological and organic methods to eliminate the need for chemicals that present significant health risks to children, families, pets and water resources.

Root Inspection: The drench test will not show the presence of billbug larvae, black turfgrass ataenius larvae or white grubs (masked chafers, May beetles or June beetles). To find white grubs, dig or cut beneath the thatch and check the soil around the roots and crowns where the roots and stems meet. When there are numerous grubs, you will see that the roots are eaten away, and the turf can be rolled back like a carpet. If you find more than one billbug larvae, six white grubs, or 40 black turfgrass ataenius grubs per square foot, control is needed.

Tug Test: Grasp the stems of the turf that have turned brown and pull straight up. If the stem breaks off easily and upon inspection of the broken ends they seem to be filled with a fine sawdust-like material, then billbugs have been active.

Pesticide Types

Broad-spectrum insecticides including carbayl and pyrethroids are available, however they pose risks for beneficial organisms and should only be used when safer pesticides aren?EUR??,,????'???t working. Several companies have developed organic pesticides that are safe to use around children and pets, such as Serenade made by AgraQuest, a biotech firm that has developed a pesticide from naturally occurring microorganisms.

Application of Controls

It is important to apply controls at the proper site and the right time. For surface applications: Mow the grass first to reduce the thatch, irrigate and let the grass dry before applying the insecticide for caterpillars and other leaf-feeders that eat blades and stems. Spot treatments are sufficient in some cases. Don?EUR??,,????'???t treat if rain is expected. Don?EUR??,,????'???t irrigate for 48 hours after application to allow the insecticide to remain on the leaves as long as possible. Sprays are preferred over granules.

Below the soil treatments: Required when treating white grubs and other root-feeders. Wait to irrigate until after the application so the insecticide is moved down into the lawn. Granular is preferred. A light pre-application irrigation will aid insecticide movement into the soil.

If cultural practices are not preventing damage and treatment is warranted, choose selective, least toxic, IPM-compatible products (see Table 2) whenever possible.

Make applications during the evening if possible because some of the chemicals may cause plant injury at temperatures above 100-degrees F. Check the compatibility chart or the pesticide label before mixing two or more types of chemicals. Mixing may cause the chemicals to lose potency or burn the plants.

Using Integrated Pest Management (IPM) Programs

The goal of an IPM program is not to eliminate the pests but to manage them and maintain them at an acceptable level. This doesn?EUR??,,????'???t mean you?EUR??,,????'???ll never have to use pesticides, but it will limit the instances when pesticides are needed.

Eugene, Oregon has a grounds maintenance program that was started in the early l980s and includes all the city?EUR??,,????'???s public parks and recreation areas. They use a variety of IPM methods that include water blasting to remove aphids, insecticidal soaps and limited use of pesticides. In using an IPM program, landscape managers can incorporate preventative practices in combination with non-chemical and chemical pest controls to minimize the use of pesticides and promote natural control of pests.