Obliquebanded leafroller (Choristoneura rosaceana)
Orange tortrix (Argyrotaenia franciscana = A. citrana)
Pest description and crop damage Both species are found in blueberries. Depending on the region, one species may be more dominant than the other. Adults of these two species are buff-colored moths with a wing span of 12-20 mm, and bell-shaped at rest. As the name indicates, the obliquebanded leafroller moth has a dark band across its wings. The larvae of the orange tortrix are light cream to green with light brown heads, and are up to 12 mm long at maturity. Obliquebanded larvae can be 12-25 mm long and have darker green bodies with dark brown to black heads. The larvae roll and tie leaves together with silk for shelter and feeding; they wriggle and thrash about violently when disturbed. Eggs are green and laid on leaves in clusters of up to 200 eggs. They hatch in about 10 to 14 days.
The larvae feed on leaves, which causes relatively minor damage. Feeding on growing points on young plants can promote undesirable branching. Loss of fruit quality can occur from binding of leaves to developing fruit, and if the larvae contaminate the fruit in mechanically harvested fields. Larval feeding on blossoms is thought to spread Botrytis fruit disease.
Biology and life history Both species overwinter as larvae on a variety of host plants. Larvae may feed during warm periods in winter but become active in spring with onset of new growth. Pupation occurs within the larval leaf roll. Depending on species, adult moths emerge from April to July. These adults lay eggs for the next generation. There are two to three generations per year.
Scouting Observe early spring growth for rolled leaves and feeding damage on new growth. Larvae move from plant to plant, and between fields, on silken threads; this silk can be easily seen upon close inspection or if viewed in the slanting sunlight. Pheromone traps are available for monitoring adult male flight. These can help to determine the timing of adult emergence and timing of larvae presence. Pheromone traps should be placed in fields beginning in late April or May and checked weekly. Starting one week after peak flight, leaves can be examined for larval infestation.
Very low temperatures in winter significantly reduce overwintering populations. Spiders and parasitic/predatory insects greatly reduce leafroller populations throughout the year.
Removal of overwintering sites, such as rolled leaves on the ground or plastered to canes, can reduce next year's population. Avoid use of broad-spectrum insecticides which can disrupt natural enemies.
Management-chemical control: HOME USE
- superior-type oil-Some formulations are OMRI-listed for organic use.
Avoid making applications of insecticides to plants in bloom to avoid bee injury. Follow all label directions.
- azadirachtin (neem oil)-Some formulations are OMRI-listed for organic use.
- Bacillus thuringiensis var. kurstaki-Some formulations are OMRI-listed for organic use.
- carbaryl-In severe infestations of leafrollers, three applications may be necessary: first, May 15; second, June 1; third, June 15. The extent of infestation should determine the number of applications. Do not apply carbaryl during blossoming-extremely toxic to bees.
- kaolin-Applied as a spray to leaves, stems and fruit it acts as a repellant to some insect pests.
- pyrethrins-Some formulations are OMRI-listed for organic use.
- spinosad-Some formulations are OMRI-listed for organic use.
- zeta-cypermethrin-Toxic to bees; do not apply when bees are foraging.
Management-chemical control: COMMERCIAL USE
- azadirachtin (Neemix and other brands)-Consult label for rate. PHI 0 days. Some formulations are OMRI-listed for organic use.
- Bacillus thuringiensis (Bt) (several brands)-Consult label for rate. PHI 0 days. A spreader-sticker increases efficacy. OMRI-listed for organic use.
- bifenthrin (Brigade and other brands) at 0.033 to 0.1 lb ai/a. PHI 1 day.
- carbaryl (Sevin and other brands) at 1.5 lb ai/a. PHI 7 days. Use postbloom only. Latex-based formulations such as Sevin XLR Plus are less hazardous to bees.
- chlorantraniliprole (Altacor) at 0.066 to 0.099 lb ai/a. PHI 1 day.
- esfenvalerate (Asana XL) at 0.025 to 0.05 lb ai/a. PHI 14 days. Washington and Oregon only. Apply prebloom or postbloom only. Acts like a bee repellent; do not apply within 7 days of pollination.
- fenpropathrin (Danitol) at 0.2 to 0.3 lb ai/a. PHI 3 days. Do not exceed two applications per season.
- indoxacarb (Avaunt) at 0.11 lb ai/a. PHI 7 days.
- methomyl (Lannate) at 0.45 to 0.9 lb ai/a. PHI 3 days. Do not apply during bloom.
- methoxyfenozide (Intrepid 2F) at 0.25 lb ai/a. PHI 7 days. For overwintering populations, make one to two applications between budbreak and petal fall, when young larvae are active. For the summer generation, begin applications at peak moth flight. Additional applications at 10- to 14-day intervals may be required under high pest pressure. Do not exceed three applications per season.
- novaluron (0.83EC) at 0.13 to 0.19 lb ai/a. PHI 8 days. Apply when larvae are young and small.
- phosmet (Imidan 70W) at 0.93 lb ai/a. PHI 3 days. Do not exceed five applications per season. Do not apply to bloom.
- pyriproxyfen (Esteem) at 0.1 lb ai/a. PHI 7 days. Apply when egg-laying begins and again at petal fall.
- spinetoram (Delegate WG) at 0.05 to 0.09 lb ai/a. PHI 3 days. SLN 24c OR-170016 for Delegate allows a 1-day PHI in Oregon only; read label carefully for restrictions on number of applications allowed. Toxic to bees for three hours following treatment. Do not apply when bees are foraging.
- spinosad (Success or Entrust) at 0.062 to 0.09 lb ai/a. PHI 3 days. SLN 24c OR-160013 and WA-140014 for Entrust SC formulation allow a 1-day PHI in Washington and Oregon only. Target application to small larvae or eggs at hatch. Toxic to bees for three hours following treatment. Do not apply when bees are foraging. Entrust is OMRI-listed for organic use.
- tebufenozide (Confirm 2F) at 0.25 lb ai/a. PHI 14 days. For overwintering populations, make one to two applications between budbreak and petal fall, when young larvae are active. For the summer generation, begin applications at peak moth flight. Additional applications at 10- to 14-day intervals may be required under high pest pressure. Do not exceed 64 fl oz product/a per season
- zeta-cypermethrin (Mustang) at 0.05 lb ai/a. PHI 1 day.