Insect, mite, or nematode damage to turf is often mistaken for a disease, drought, or fertilizer problem. The symptoms are often similar: chlorosis, wilting, die-back. As a result, it is not uncommon for these pests to inflict extensive damage before their presence is realized. The first step toward the alleviation of the problem must be pest identification. Therefore descriptive keys to insects and their damage are provided in this section.
Information concerning the type of pest, its feeding habits, and its life cycle is essential in determining the appropriate insecticide to use as well as the rate and method of application that will give satisfactory control. One of the fundamental purposes of this manual is to provide relevant information on which to base these control decisions.
Serious insect and related pest infestations are sporadic and unpredictable. Therefore, the application of pesticides to turf should not be preventive in nature. It is wiser economically and ecologically to treat infestations only as they occur. In this way, the development of resistance to pesticides will be delayed, the buildup of harmful residues will be unlikely and populations of beneficial organisms can be maintained.
Preventive Control. A limited number of preventive measures are applicable to both commercial turf and home lawn insect control. These include sanitary and cultural practices. New golf greens are sometimes fumigated before the turf is established to reduce nematode, disease, and insect pests. Thatch removal, a sanitary practice, eliminates a sheltered hiding place for many turf insects, especially white grubs and sod webworms. Hiding under the thatch layer, these pests are protected from bird and insect predators in the summer and are insulated against cold weather in the winter. Thatch protects pests in another way by preventing pesticides from penetrating to the soil where insects are located. Absorbed by thatch, insecticides become deactivated.
Good cultural practices, such as proper fertilization, irrigation, weed control, and other maintenance operations, help improve the recuperative potential of turf damaged by insects or other pests. Although a well-managed vigorous turf may attract pests, it can tolerate a higher pest population without serious harm than can a turf in poor condition. Sod and sprig growers should be alert for insect infestations and supply pest-free planting stock to the consumer.
Likewise, care should be taken to prevent the use of infested soil for topdressing or soil amendment. Fumigation or heat sterilization can be employed to eliminate this problem. Although some reliable fumigants are on the market, heat treatment of infested soil requires less time and money and is more effective against a wider range of pest problems. Sterilization of soil with steam heat at 82°C (180°F) for 30 minutes kills most weed seeds, soil insects, pathogenic fungi, pathogenic bacteria, and nematodes. Stationary or movable sterilization (pasteurization) equipment is available.
Although there is considerable potential in insect and nematode resistant cultivars, few resistant varieties of turf have been developed (Table 1). The eventual release of additional resistant cultivars in the future will provide additional safe, inexpensive, and convenient means of reducing pest damage.
|Tolerant to Bermudagrass mite*, sod webworms, and mole crickets|
|Susceptible to the Bermudagrass mite*; somewhat resistant to nematode injury|
|Good resistance to Helminthosporium spp. (fungus leaf spot) and Bermudagrass mite; susceptible to armyworm, sod webworm, and scale insects|
|Very susceptible to smog injury and sod webworm|
|Good resistance to Bermudagrass mite*; susceptible to hunting billbug|
|Susceptible to dollar spot|
|Susceptible to hunting billbugs and nematodes|
Chemical Control. Once a pest infestation is recognized, chemical control may be necessary. Pest control chemicals are sold as emulsifiable concentrates (EC), wettable powders (WP), soluble powders (SP), granules (G), dusts (D), or baits (B). Pesticide applications on turf usually need to be watered into the soil thoroughly. Therefore, spray formulations of wettable powders or emulsifiable concentrates are generally preferred over dusts.
Chemical Compatibility. Most insecticides recommended for turf pest control are compatible with each other. As a result, they can be mixed together if more than one chemical is necessary to control a complex pest situation. Mixtures can also be made with most modern fungicides, e.g., benomyl, captan, maneb, thiram, ferbam, and ziram. Carbophenothion (Trithion), which sometimes is used by commercial applicators to control chinch bugs is incompatible with the fungicides captan (Orthocide), captafol (Difolatan), and folpet (Phaltan). With most modern pesticides, incompatibility problems result only when these chemicals are mixed with summer oils, lime-sulfur, wettable sulfur, copper-base fungicides, or arsenical insecticides. Mixtures of these groups of pesticides may be phytotoxic, react to form different and undesirable compounds, or have an unstable physical form which makes application hazardous.
Application. To apply the correct amount of pesticide to infested turf, it is necessary to determine the area of turf to be sprayed. Recommendations are usually in the amount of pesticide to be applied per 100 sq ft (approximately 9.3 centiare). It is important to figure accurately the amount of pesticide to use and to calibrate accurately the delivery system (sprayer, spreader, etc.) to ensure adequate control. Using more chemical than is recommended is wasteful and expensive, whereas not using enough results in inadequate control. For specific calibration information, consult current state agricultural extension service recommendations.
A wide variety of equipment is available for turf insect control. Power sprayers are used to apply solutions of wettable powders or emulsifiable concentrates on golf courses, cemetery lawns, or other sizeable, continuous areas of turf. The estate-type sprayer, a small wheel-mounted sprayer, with flat fan nozzles is also used in these situations.
For home lawns, hand-operated sprayers, compressed air sprayers, and jar attachments for the garden hose give adequate results. Hose attachments which require 10 to 15 gallon (26 to 39 liters) of water to empty the jar deliver enough pesticide to treat 500 sq ft (approximately 56 centiare) of turf. Such attachments are preferable to those which utilize less water.
Granular formulations are easily applied with power- or hand-operated fertilizer distributors as well as hand-held shakers. Spreading the granules evenly is often difficult. Although not commonly used, dusts can be applied to turf with power- or hand-operated dusters. As soon as pesticide granules or dusts are dispensed, the treated turf should be watered thoroughly.
Baits can be applied in much the same way as granular formulations. Unlike the granular formulations, however, baits should never be watered into the turf. They are best applied late in the day, after irrigation or rain. Restrictions concerning pets and humans on bait-treated turf may exist, so read the pesticide label carefully.
Care of Equipment. The tanks of power-driven sprayers should be flushed with water after each use. All nozzles and strainers should be cleaned. Before storing the sprayer for a long period of time, fill the tank with clean water and 2 to 5 gallons of oil. Pump this mixture out until the tank is dry. A think film of oil will be left in the tank to help prevent corrosion.
Small garden sprayers with metal tanks should be washed out three times after each use with clear water to prevent corrosion even with stainless steel tanks. For metal sprayer tanks a small amount of household ammonia in the sprayer tank, shaken thoroughly to neutralize the corrosive effects of any insecticide residue, will prolong the life of the tank. The sprayer tank should then be allowed to dry completely. The plunger rod should be lightly oiled.
Fertilizer hoppers used to apply granular pesticides should be rinsed thoroughly after each use to remove any corrosive granules. Dusters require no appreciable maintenance as long as they are kept dry. An occasional drop of oil on the plunger rod or other moving parts may be advisable unless the duster is fitted with rubber washers. If this is the case, the steel rod and plunger should be lubricated with graphite. The use of oil will ruin the rubber washers.
Precautions. As in all chemical pest control operations, caution is necessary. Heed the pesticide label and follow instructions closely. Do not apply insecticides to turf where there are people or animals. After application, keep everyone away from the area until the insecticide has been watered in and the grass has dried. Never clean sprayers or dump pesticides in or near streams, lakes, or ponds. State agricultural extension service recommendations and pesticide labels elaborate on safety information.