Integrated Pest Management
Powdery Mildew (Tomatoes)
Feeding galleries on peach tree.
Exit holes in peach tree.
HOSTS
- Most tree fruits
- Ornamentals, including hawthorn, cherry and others
DESCRIPTION
Shothole borer adults are tiny, brown-black beetles, about 3 mm in size. Larvae are small, creamy-white and legless, with dark brown mouthparts.
BIOLOGY
In Utah, there are 2-3 generations per year. Regardless of the number of generations, adults fly continuously from spring to fall, so trees can be attacked at any time. They overwinter as larvae and adults emerge in April-May. Adults fly to weakened or stressed trees, and bore under the bark to create a short, parental “egg gallery” in the sapwood. Larvae hatch and feed in individual galleries for 6-8 weeks, pupate, and then emerge as adults for the second generation. The larvae of this generation overwinter in the wood and pupate in spring.
SYMPTOMS
- Small, round exit holes
- Clear tendrils of gum exuding from entrance holes
- Boring dust (frass) in the bark crevices
- Yellowing and wilting foliage
- Branch dieback
GENERAL MANAGEMENT
Because shothole borers preferentially attack stressed or injured trees, management strategies aimed at keeping trees healthy are important. Soil should contain adequate moisture to a depth of about 20 inches. Soil moisture can be tested by pushing a long screwdriver or slim metal rod into the soil. The metal will easily penetrate moist soil, and will stop when dry soil is reached. Deep watering should be done once a week during hot summer months (July, August) and less frequently in the cooler months.
Other management strategies include:
- Protect tree bark from winter injury.
- Apply white tree wrap on the trunk from December to April, or paint trunks with a 50% white latex paint / 50% water solution.
- Replace old, diseased, injured, weakened, or stressed trees.
- Prune dead or dying branches.
- Remove and burn, chip, solarize, or debark infested branches, stumps or trees, as old wood can attract beetles.
INSECTICIDES
Insecticide applications for shothole borer are generally not recommended. Additionally, there no products available that include shothole borer on the label. However, chemical products may be used IF the tree or tree type (fruit, or ornamental trees) is listed on the label. Possible products to try include carbaryl, bifenthrin, permethrin, or spinosad, once a month throughout the season. Systemic insecticides (e.g., imidacloprid) are NOT effective against shothole borer.