Apricot-Peach twig borer

Anarsia lineatella

Pest description and crop damage Peach twig borer is a European insect first found in California in the 1880s. It is a major pest of apricots, peaches, plums, and prunes. The adult is a steel-gray moth with white and dark scales, about 0.33 to 0.5 inch long. The larva is a caterpillar, about 0.5 inch long, with a dark brown head and distinctive, alternating light and dark bands on the body. The pupa is smooth and brown. Larvae injure fruit and trees by feeding on the buds and twigs early in the season. Later in the season, the larva bores into the shoots causing a characteristic "flagging" or wilting of the new growth. Later generations of larvae feed on shoots or fruit, disfiguring the fruit. Flagging of twigs indicates an infestation.

Biology and life history The borer overwinters as an immature larva in tunnels constructed within the crotches of twigs and branches. These overwintering sites can be identified by the small chimneys of frass and wood fragments produced by the feeding of the larvae. Larva become active by the pink bud stage and emerge to feed on buds and young leaves. Later the larvae will bore into shoots. These larvae eventually leave the mined shoots to pupate. Adults then emerge in mid-to-late May. Eggs are laid on fruit, shoots, or undersides of leaves. Eggs are yellowish-white to orange. The eggs hatch, and these larva feed on shoots and immature fruit. The next adult flight is in mid July. Some of the larvae from this flight overwinter, the rest produce a partial third flight.

Pest monitoring Use pheromone traps to time sprays to target the young larvae before they bore into tissues. Scout for flagging of shoots early in season. Detection indicates a need to protect fruit from later generations of peach twig borer.

Management-cultural control

Cut out and destroy mined shoots below the wilted area to eliminate larvae. Overwintering larvae may be found and destroyed under thin bark in branch crotches. Look for a buildup of chewed bark and frass (excrement).

Management-chemical control

Early sprays aimed at the newly-hatched larvae, before they bore into the shoot or fruit, will provide the best control of peach twig borer.

Management-chemical control: HOME USE

Dormant-season spray

  • superior-type oil-Some formulations OMRI-listed for organic use.

Growing-season spray

For most effective control, target the young larvae with cover sprays during pre-bloom or petal fall.

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.

  • acetamiprid
  • azadirachtin-Some formulations are OMRI-listed for organic use.
  • carbaryl
  • esfenvalerate
  • gamma-cyhalothrin
  • kaolin-When sprayed on leaves, trunks, and fruit, kaolin acts as a repellant to some insects. Some formulations are OMRI-listed for organic use.
  • lambda-cyhalothrin
  • pyrethrins-Some formulations may be OMRI-listed as organic.
  • spinosad-Some formulations may be OMRI-listed as organic.
  • zeta-cypermethrin

Management-chemical control: COMMERCIAL USE

For most effective control, target the young larvae with cover sprays during pre-bloom or petal fall.

Delayed-dormant and prebloom spray

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.

  • horticultural mineral oil (rates vary, check product label) + carbaryl (Sevin 4F) at 4 to 5 quarts/a. REI 12 hr. Extremely toxic to aquatic invertebrates; avoid spray drift and runoff to surface waters.
  • chlorantraniliprole (Altacor 35 WDG) at 3 to 4.5 oz/a. REI 4 hr. May be applied with a registered horticultural mineral oil.
  • flubendiamide (Belt SC) at 3 to 4 fl oz/a. REI 12 hr.
  • phosmet (Imidan 70W) at 0.75 to 1 lb/100 gal water (4.25 lb/a). REI 7 days. Extremely toxic to fish; avoid spray drift and runoff to surface waters.
  • spinetoram (Delegate 25WG) at 3.0 to 7 oz/a. REI 4 hr.
  • spinosad-
    • Entrust 80W at 0.4 to 0.8 oz/100 gal water (1.25 to 2.5 oz/a). REI 4 hr. OMRI-listed for organic use.
    • Success 2F at 1.3 to 2.7 fl oz/100 gal water (4 to 8 fl oz/a). REI 4 hr. May act slowly.

Bloom spray

  • Bacillus thuringiensis kurstaki-Check label for rates. REI 4 hr. Nontoxic to bees. This biologically derived material is slow acting and requires good coverage and multiple applications in order to be effective. Apply when forecast calls for warm daily temperatures. This acts as a stomach poison and is less effective during cool weather, when larvae are not actively feeding. Some formulations are OMRI-listed for organic use.

Petal fall, spring, and summer sprays

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.

  • Bacillus thuringiensis kurstaki-Check label for rates. PHI 0 days. REI 4 hr. Nontoxic to bees. This biologically derived material is slow acting and requires good coverage and multiple applications in order to be effective. Apply when forecast calls for warm daily temperatures. This acts as a stomach poison and is less effective during cool weather, when larvae are not actively feeding. Some formulations are OMRI-listed for organic use.
  • chlorantraniliprole (Altacor 35 WDG) at 3 to 4.5 oz/a. PHI 10 days. REI 4 hr.
  • flubendiamide (Belt SC) at 3 to 4 fl oz/a. PHI 7 days. REI 12 hr.
  • methoxyfenozide (Intrepid 2F) at 8 to 16 fl oz/a. PHI 7 days. REI 4 hr.
  • phosmet (Imidan 70W) at 0.75 to 1 lb/100 gal water (4.25 lb/a). PHI 14 days. REI 7 days. Extremely toxic to fish; avoid runoff and spray drift to surface waters.
  • spinetoram (Delegate 25WG) at 4.5 to 7 oz/a. PHI 14 days. REI 4 hr.
  • spinosad-
    • Entrust 80W at 0.4 to 0.8 oz/100 gal water (1.25 to 2.5 oz/a). PHI 14 days. REI 4 hr. OMRI-listed for organic use.
    • Success 2F at 1.3 to 2.7 fl oz/100 gal water (4 to 8 fl oz/a). PHI 14 days. REI 4 hr. May act slowly.

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