Description of the Pest
Loopers arch their backs as they crawl. Cabbage loopers are light green and usually have a narrow, white stripe along each side and several narrow lines down the back. The dome-shaped eggs are laid singly on the undersurfaces of older leaves. Adult moths have brown, mottled forewings marked in the center with a small, silver figure 8.
Young cabbage looper larvae feed primarily on the underside of lower leaves, skeletonizing them. Larger cabbage loopers chew entirely through leaves and flowers.
A number of parasites, both tachinid flies and parasitic wasps, attack Lepidoptera larvae and reduce their population growth rate. However, most of these larvae continue feeding through to the last instar, so parasitized larvae will still damage crops. Viruses also do not usually kill the larvae until later instars. Trichogramma spp. are commercially available egg parasites that can be effective against cabbage looper. Applying insecticides other than Bacillus thuringiensis (Bt) products are likely to exclude parasites because their residue are lethal to these beneficial insects. For more information, see BIOLOGICAL CONTROL.
Because these pests feed on a large variety of plant species, keep production areas free of weeds (e.g., mustards) that serve as hosts to cabbage loopers. Exclusion of winged adults can be accomplished by covering openings to the greenhouses with screens. Screens are especially important when lights are used at night in greenhouses to control flowering because lights attract adult moths. Individual seedling flats may also be covered with screens to exclude adults and larvae. Row covers can be a practical measure to exclude moths in field production as long as the mesh prevents entry of adults and the row cover is held above the plant surface to eliminate oviposition through the fabric.
Monitoring and Treatment Decisions
If Bt sprays are planned, use pheromone traps to determine adult flight activity and mating. Once adults are caught in traps, it is very likely that larvae are present and Bt should be applied as soon as possible because it is most effective against young larvae. Use regular visual inspections of plants to detect larvae and their damage. For guidelines on when to treat, see ESTABLISHING ACTION THRESHOLDS.
Selected Materials Registered for Use on Greenhouse or Nursery Ornamentals
Read and follow the instructions on the label before using any pesticide. Before using a pesticide for the first time or on a new crop or cultivar, treat a few plants and check for phytotoxicity. Also consider pesticide resistance management and environmental impact.
|Manufacturer||REI1||Mode of action2||Comments|
(PT Pyrethrum TR)
|Whitmire MicroGen||12||3/—||An aerosol.|
|insect growth regulator||A.||azadirachtin
|OHP||4||un||Must contact insect. Repeat applications as necessary. Label permits low-volume application.|
|Chemtura||12||15||Use no more than twice per year and don't exceed 52 oz/acre/year. Don't use on poinsettia.|
|Valent||4||11||Most effective against early instar larvae; pheromone trapping recommended for timing applications.|
(Orthene T, T&O Spray)
|Valent||24||1B||A number of chrysanthemum varieties have exhibited phytotoxic reactions. In greenhouse only labeled for greenhouse use on anthurium, cacti, carnation, rose, orchids, some foliage plants, young poinsettia, and some varieties of chrysanthemum. Can stunt new growth in roses.|
(PT 1300 Orthene TR)
|Whitmire MicroGen||24||1B||An aerosol only for greenhouse use.|
|Whitmire MicroGen||12||3||Check label. A fogger for greenhouse use only.|
|FMC||12||3||Label permits low-volume application.|
|OHP||12||3||Label permits low-volume application.|
(Tame 2.4EC Spray)
|Valent||24||3||Label permits low-volume application.|
|Wellmark||12||3||Label permits low-volume application. Also labeled as a cutting dip at 5 fl oz/100 gal.|
|FMC||12||3||Direct application to blooms may cause browning of petals. Marginal leaf burn may occur on salvia, diffenbachia, and pteris fern. Label permits low-volume application. Do not apply more than 2 lb a.i./acre/year.|
|4||5||Do not apply more than 10 times in a 12-month period. Compatible with most beneficials, but highly toxic to bees and hymenopteran parasites. Direct contact can cause significant mortality to Phytoseiulus persimilis.|
|1||Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing.|
|2||Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee).|
|3||PBO = piperonyl butoxide|
|#||Acceptable for use on organically grown ornamentals.|
|*||Restricted use material. Permit required for purchase or use.|