Pacific spider mite (Tetranychus pacificus)
Strawberry spider mite (Tetranychus turkestani)
Twospotted spider mite (Tetranychus urticae)
Pest description, crop damage and life history
Pest monitoring There is no precise survey technique for evaluating spider mite infestations. Infestations usually begin on the lower portions of the plants and move upward as mite numbers increase. Evaluating spider mite infestations is most efficient if randomly selected, older, lower leaves are picked and inspected for stippling on the upper surface and webbing, mites, and feeding scars on the lower surface. Areas in the field where dust accumulates or weedy areas are good places to scout for spider mites.
Spider mite populations may be held at very low levels by a number of insect and mite predators, particularly early in the year. Thrips are effective early year predators, feeding primarily on spider mite eggs.
Commercial releases of predatory mites are used to control spider mites in greenhouses. In Florida, predatory mites were used to control spider mites in strawberries. Spider mites provide an important food source for predators such as minute pirate and bigeyed bugs.
Spider mite problems can be reduced by keeping fields and field margins clean of weed hosts. Spider mite populations may increase more rapidly in areas where dust deposits are heavy. Reducing dust may reduce the spider mite problem. Spider mites are usually less severe in sprinkler-irrigated fields than in furrow-irrigated fields. Excessive nitrogen fertilization also may contribute to population buildup. Minimizing early year insecticide applications, which reduce populations of beneficial insects, will reduce spider mite outbreaks. Minimizing early year insecticide applications of broad spectrum insecticides, which reduce populations of beneficial insects, will reduce spider mite outbreaks.
Management-chemical control: HOME USE
- azadirachtin (neem oil)-Some formulations are OMRI-listed for organic use.
- insecticidal soap-Apply control measures when mites first appear, and repeat application as necessary. Good coverage, especially on undersides of leaves, is essential. Some formulations are OMRI-listed for organic use.
- plant essential oils (clove, garlic, rosemary etc.)-Some formulations are OMRI-listed for organic use.
- sulfur-Some formulations are OMRI-listed for organic use.
Management-chemical control: COMMERCIAL USE
- borate complex (Prev-Am) applied as a 0.4% to 0.8% solution. Spray to complete coverage. PHI 12 hr. REI 12 hr. Retreatment interval 4 days. OMRI-listed for organic use.
- dicofol (Dicofol 4E) at 0.5 to 1.5 lb ai/a. Do not exceed one application per season. PHI 21 days. REI 33 days.
- dimethoate at 0.5 lb ai/a. PHI 0 days. REI 48 hr. Do not feed treated vines.
- insecticidal soap (M-Pede) at 1 to 2% (see label for gal/a). Potassium salts of fatty acids. PHI 0 days.
- naled (Dibrom) at 0.94 lb ai/a. PHI 1 day. REI 48 hr. Do not apply within 25 ft of an aquatic habitat, 150 ft if applied by air.
- phorate (Thimet)-Do not exceed 1.5 lb ai/a. PHI 60 days. REI 48 hr, or 72 hr if annual rainfall is less than 25 inches. Use at planting only. Do not graze or feed to livestock. Toxic to fish and wildlife.
- propargite (Comite) at 1.6 to 2.4 lb ai/a. PHI 14 days. REI 9 days. Do not exceed 3.7 lb ai/a per season. Retreatment interval 21 days. Do not feed any parts of treated plants to livestock. Do not use more than twice per year.
- sulfur at 2.25 to 6.75 lb ai/a. REI 24 hr. PHI: consult processor.