European (filbert) leafroller (Archips rosana)
Fruittree leafroller (Archips argyrospila)
Obliquebanded leafroller (Choristoneura rosaceana)
Pandemis leafroller (Pandemis pyrusana)
Pest description and crop damage There are several species of leafroller pests of tree fruits. The larvae of these moth species can use native plants as hosts as well as fruit trees. They all cause similar damage to the trees, but differ in their appearance and in their life cycle. The principal leafroller pests of fruit trees can be divided into single-generation moths, such as the fruittree leafroller and the European leafroller, and two-generation moths, such as the obliquebanded leafroller and pandemis leafroller. Adults of these species range from fawn-color to dark brown. There are distinctive bands or mottling on the wings. Wingspans range from 0.75 to 1 inch. The larvae of these species are all green caterpillars with a light brown to black head, depending on the species. Larvae roll and tie leaves together for shelter and feeding. They thrash about violently when disturbed and may drop from the leaf suspended by a silken thread. Feeding on growing points on young plants can promote undesirable branching. Larvae also feed on the surface of the fruit, causing deep, russeted scars.
Biology and life history The single-generation leafrollers overwinter as egg masses on twigs and branches. Eggs hatch in spring as buds are opening until petal fall. The larvae feed for 4 to 6 weeks, then pupate in the rolled leaves and emerge as moths in early summer. The overwintering eggs are laid in July. Two-generation leafrollers overwinter as immature larvae under the bark on scaffold branches of a variety of host plants. Larvae may feed during warm periods in winter but become active in spring with onset of new growth. They feed for several weeks, and then pupate in rolled leaves. Adult moths emerge in late April to May. These lay eggs for the next generation. The next generation hatches in early summer and does the most damage.
Pest monitoring Observe early spring growth for rolled leaves and feeding damage on new growth.
Very low temperatures in winter significantly reduce overwintering populations of larvae. Spiders and parasitic wasps, as well as predators like the brown lacewing, greatly reduce leafroller populations throughout the year.
Home orchardists: Hand-pick rolled leaves containing larvae or pupae. Removal of overwintering sites, such as rolled leaves on the ground or plastered to canes, can reduce next year's population.
Management-chemical control: HOME USE
- superior-type oil
Warning: Many pesticides are hazardous to bees. Look for bee precautionary statements on product labels and do not use these products during bloom or if bees are foraging in the orchard.
- azadirachtin (neem oil)-Some formulations OMRI-listed for organic use.
- Beauveria bassiana-Some formulations are OMRI-listed for organic use.
- carbaryl-Highly toxic to bees.
- esfenvalerate-Highly toxic to bees.
- gamma-cyhalothrin-Highly toxic to bees.
- horticultural mineral oil-Some formulations OMRI-listed for organic use.
- kaolin-Applied as a spray to leaves, stems, and fruit, it acts as a repellant to some insect pests. Some formulations are OMRI-listed for organic use.
- lambda-cyhalothrin-Highly toxic to bees.
- plant-derived essential oils-Some have shown efficacy against leafrollers. Some formulations are OMRI-listed for organic use.
- pyrethrins (often as a mix with other ingredients)-Some formulations are OMRI-listed for organic use.
- spinosad-Highly toxic to bees. Some formulations are OMRI-listed for organic use.
- zeta-cypermethrin-Highly toxic to bees.
Management-chemical control: COMMERCIAL USE
Dormant and delayed-dormant spray
- horticultural mineral oil (rates vary; check product label)-Use oil at this concentration only in the dormant period. REI varies; check product label. Some formulations are OMRI-listed for organic use.
- chlorantraniliprole (Altacor 35WDG) at 3 to 4.5 oz/a. REI 4 hr.
- spinetoram (Delegate WG) at 4.5 to 7 oz/a. REI 4 hr.
- Entrust SC at 1.25 to 2.5 oz/a. REI 4 hr. OMRI-listed for organic use.
- Success at 4 to 8 fl oz/a. REI 4 hr. Results are best when applied at petal fall. May act slowly.
- Bacillus thuringiensis kurstaki-Check labels for rates. REI 4 hr. Bt products work best if temperatures exceed 50°F over 3 consecutive days. Some formulations are OMRI-listed for organic use.
Spring and summer spray
- Bacillus thuringiensis kurstaki-Check labels for rates. REI 4 hr. PHI 0 days. Bt products work best if temperatures exceed 50°F over 3 consecutive days. Apply sprays 14 to 21 days apart. Some formulations are OMRI-listed for organic use.
- chlorantraniliprole (Altacor 35WDG) at 3 to 4.5 oz/a. REI 4 hr. PHI 10 days.
- flubendiamide (Belt 4SC) at 3 to 4 fl oz/a. REI 12 hr. PHI 7 days.
- methoxyfenozide (Intrepid 2F) at 8 to 16 fl oz/a. REI 4 hr. PHI 7 days. For each generation, apply when egg hatch begins and before larvae enter fruit. Reapply in 10 to 14 days to ensure complete coverage of rapidly expanding fruits or foliage, or under conditions of high infestation or sustained moth flight.
- spinetoram (Delegate WG) at 1.1 to 1.75 oz/100 gal water (4.5 to 7 oz/a). REI 4 hr. PHI 7 days. Apply no less than one week apart, with a maximum 4 applications per season.
- Entrust SC at 1.25 to 2.5 oz/a. REI 4 hr. PHI 7 days. OMRI-listed for organic use.
- Success at 4 to 8 fl oz/a. REI 4 hr. PHI 7 days. Results are best when applied at petal fall. May act slowly.
Resistance management Leafrollers can develop resistance rapidly to chemical controls.