Plum and prune-Cutworm (climbing)


Spotted cutworm (Xestia c-nigrum)

Variegated cutworm (Peridroma saucia)

Pest description and crop damage Several species of cutworms attack tree fruits. The adults are large moths ranging in color from gray to brown with spots on the wings. These moths are attracted to lights. Larvae are dirty white, reddish, gray or black caterpillars up to 2 inches long. The larvae of these moths feed on buds and leaves, chewing holes in buds and ragged holes out of leaves. They also feed on the growing tips, particularly on small trees or in high density plantings. On larger trees, most of the feeding is on the lower branches, and may be concentrated to a few stems or limbs, while other stems are undamaged.

Biology and life history Weeds are the preferred source of food for these larvae, and eggs typically are laid on weeds around the trees. Depending on species, they may overwinter as pupae or larvae in the soil. The larvae spend the day in the soil, and then climb up the tree during the day to feed, often following the same path.

Management-cultural control

Control weeds, grasses, and debris in the orchard that provide cover. Encourage natural enemies of cutworms like birds and spiders. If practical, seek out and hand-pick cutworm larvae, at night using a flashlight to find them. Scratch the soil at the base of plants to find larvae in the daytime. Caterpillars are trapped by tying plastic wrap tightly around branches and trunk, then applying a sticky adhesive to the plastic wrap. Remove these wraps in the fall.

Management-chemical control: HOME USE

  • azadirachtin (neem oil)-Some formulations are OMRI-listed for organic use
  • carbaryl-Highly toxic to bees.
  • esfenvalerate-Highly toxic to bees.
  • gamma-cyhalothrin-Highly toxic to bees.
  • imidacloprid-Plum only. Highly toxic to bees. Soil drenches may have residual activity in woody plants lasting for 12 or more months. If short-term management is the goal, consider other approaches.
  • insecticidal soap-May require several applications. Some formulations are 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.
  • pyrethrins-Highly toxic to bees. Some formulations are OMRI-listed for organic use.
  • spinosad-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

  • chlorpyrifos (Lorsban 4E) at 0.5 pint/100 gal water (2 to 4 pint/a). Apply at dormant or delayed-dormant only and do not exceed one application per year. REI 4 days. Spray base of tree; also mow down grass and weeds. Do not graze in treated orchards. Extremely toxic to fish and aquatic invertebrates; avoid spray drift and runoff to surface waters. RESTRICTED USE IN OREGON.