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Lawn
Insects Contrary to popular belief, insects are not a common cause of residential lawn damage in California, yet lawn care products containing broad-spectrum insecticides are widely purchased and used by many homeowners. Unnecessary use of an insecticide on a lawn is not harmful to the lawn, however it does disturb the beneficial insects and can pollute the environment. Sprinkler runoff moves the insecticide off the lawn and into street gutters. In the last few years common residential insecticides have been detected in city storm drains at levels where they contaminate waterways and kill desirable insects. As a result some common insecticides will have harsher restrictions for use and will be less available to the homeowner. Most gardens contain far more types of good bugs than pest insects. These beneficial insects kill pest insects and are called natural enemies. In any pest management or plant care program, it is important to encourage these natural enemies by avoiding pesticides that kill them. One rule should be to "never apply an insecticide unless a damaging level of an insect pest is confirmed". Insecticides are only effective if applied at the right time and in the right manner. Also, the most effective treatment for one pest may not work on another. Poor lawn care, especially improper watering and planting inappropriate grass species, are more likely causes of unhealthy or dying lawns. Diseases, excess fertilizer, and dog urine also produces lawn damage resembling that of insects. Confirm presence of pest insects before applying an insecticide. How do you know if insects are causing damage? For grubs (chafer and June beetle larvae) and billbug larvae, dig around roots and look for the thick white worms. For other insects perform the following drench test. Find an area in the lawn where insect damage is suspected. Mark off about a square yard putting the edge of damage in the middle of the square. With a watering can uniformly apply one gallon of water containing an ounce or two of a liquid dish detergent (or a tablespoon of pyrethrin, diazinon, or dursban) over the designated turf area. Wait 5–10 minutes and watch for insects. The soap (or insecticide) irritates the insects and they typically squirm to the surface. If you have St. Augustine grass a very common insect pest to look for is the southern chinch bug. Other lawns could contain sod webworms, cutworms, fiery skipper worms, and billbug adults. Before applying a treatment for foliar or thatch-dwelling pests, irrigate the lawn well and then treat as soon as the plants dry. Apply the required amount of insecticide in enough water to thoroughly wet the grass down to the ground. For foliage feeders such as the fiery skipper, sod webworm, armyworms, and cutworms 2-5 gallons of water per 1000 square feet of turf works well. The bermuda grass mite as well as root feeding pests like grubs require a greater volume of water to move the pesticide into the area where the pest is feeding. Insects that feed in the thatch layer like the southern chinch bug should have treatments applied in 10-25 gallons of water per 1000 square feet of lawn. Do not water the lawn following a chemical application until absolutely necessary to prevent wilting. This will allow the insecticide to remain on the plants for the longest possible period. Do not apply insecticides when temperatures exceed 90 degrees. In general, sprays work best when treating foliar lawn pests, but granular formulations are acceptable for controlling white grubs, billbugs, chinchbugs, cutworms, skipper larvae, and the sod webworms. Granules are advantageous when attempting to control pests residing in or below the thatch layer because they move past leaf blades and partially penetrate the thatch layer. Beneficial insects are disrupted by broad-spectrum insecticides such as pyrethroids, carbamates (sevin), and to a lesser extent, organophosphates (dursban, diazinon, and orthene). Alternatives such as Bacillus thuringiensis (Bt) control a narrower range of organisms, thus preserving naturally occurring beneficial insects. Bt products are typically inexpensive, but timing is more critical for control. Since the product breaks down in sunlight, several applications may be necessary. Keep your lawn healthy by Integrated pest management (IPM) uses environmentally sound, yet effective ways to keep pests from annoying you or damaging plants. IPM programs combine several pest control methods for long term prevention and management of pest problems without harming you, your family or the environment. IPM also reduces pollution in California waterways. Successful IPM begins with you taking the time to correctly identify if a pest is causing a real problem. June 14, 2001 |