Pest description and crop damage Adult moths are 0.5 to 0.75 inch long, dark brown, with darker transverse lines on the forewings. The larvae are green with a light to dark brown head. Damage begins early in spring and includes rolling of leaves as well as feeding on foliage and buds. There is one generation each season.
Biology and life history This leafroller overwinters as eggs laid on the bark or limbs in irregular flat masses which appear grayish by spring. 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 on twigs and branches in July.
Pest monitoring Start checking for larvae around mid-March by inspecting three terminals per tree and three leaf clusters per terminal. Each terminal is a sampling unit. The terminal clusters should be examined for tightly rolled leaves and feeding damage on new growth. Check for adults by using one pheromone trap for each 5 acres, placed 6 ft high in the tree canopy starting in mid-May. Treat for larvae when infestation level is 20 to 25%. Treat for adults when catch is 40 moths per week.
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. Typically, biological control is sufficient to manage leafrollers and chemical control is rarely necessary.
Home orchardists: Hand-pick rolled leaves containing larvae or pupae.
Management-chemical control: HOME USE
Spray in spring after overwintering eggs hatch, at about the time leaves are 0.75 to 1 inch long. Control is much more effective if sprays are applied when larvae are small.
- azadirachtin (neem oil)-Some formulations are OMRI-listed for organic use.
- Bacillus thuringiensis var. kurstaki-Some formulations are OMRI-listed for organic use.
- Beauveria bassiana-Some formulations are OMRI-listed for organic use.
- kaolin-Some formulations are OMRI-listed for organic use.
- plant-derived essential oils-Some formulations are OMRI-listed for organic use and have shown efficacy against aphids.
- pyrethrins (often as a mix with other ingredients)-Some formulations are OMRI-listed for organic use.
- spinosad-Some formulations are OMRI-listed for organic use.
Management-chemical control: COMMERCIAL USE
Make spray application in spring after overwintering eggs hatch, about the time leaves are about 0.75 to 1 inch. Control is more effective if pesticide is applied when larvae are small.
- Bacillus thuringiensis var. kurstaki-See label for rates. PHI 0 days. Apply with spreader-sticker. Some formulations are OMRI-listed for organic use.
- diflubenzuron (Dimilin 2L) at 12 to 16 fl oz/a. PHI 28 days. REI 12 hr. Extremely toxic to aquatic invertebrates. Do not apply within 25 ft of bodies of water.
- emamectin benzoate (Proclaim) at 3.2 to 4.8 oz/a. PHI 14 days. REI 12 hr.
- flubendiamide (Belt) 3 to 4 fl oz/a. PHI 14 days. REI 12 hr.
- methoxyfenozide (Intrepid 2F) at 8 to 16 fl oz/a. PHI 14 days. REI 4 hr. For control of foliar feeding leafroller larvae, apply when larvae are feeding. Most effective crop protection results from application made at the initiation of egg hatch. Do not apply more than 24 fl oz/a per application or 64 fl oz/a (1 lb ai) per season. Do not apply within 25 ft of an aquatic habitat, 150 ft if applied by air.
- pyriproxyfen (Esteem 35 WP ) at 4 to 5 oz/100 gal water. Do not apply more than twice per season. PHI 21 day. REI 12 hr.
- spinetoram (Delegate WG) at 1.1 to 1.75 oz/100 gal water (4.5 to 7 oz/a). PHI 14 days. Apply no less than one week apart, with a maximum of 28 oz/per year.
- spinosad (Success 2L, Entrust SC) at 4 to 10 fl oz/a. PHI 1 day. REI 4 hr. Do not apply more than 29 fl oz/a per year. Entrust SC is OMRI-listed for organic use.