Apple Pest Management in a Reduced Crop

by Erica Pate

It’s been a tough spring, and the weekend of May 23-24 brought cold temperatures that caused extensive damage. Although the full extent of the damage has not yet been determined, many orchards have a poor fruit set or are seeing reduced fruit quality due to frost damage. Here are a few thoughts to consider when adjusting you pest management program to your crop load:

Apple scab infections need to be prevented until the end of primary scab season. Maintain protection on new growth to reduce overwintering inoculum and keep trees in good health for next year. The primary scab season has passed in most areas of the province; however primary scab lesions can occur 10-28 days after the infection event. Verify there are no scab lesions before reducing your fungicide program.

Powdery mildew can cause extensive damage to susceptible varieties like Gala, Honeycrisp, Jonagold, Idared, Cortland, Paulared, etc. Continue protecting with fungicides until terminal bud set.

Fire blight strikes have been found in commercial orchards. Remove these strikes at least weekly.

Direct insects like plum curculio, oriental fruit moth, oblique-banded leaf roller and
codling moth, if left uncontrolled, might become resident in the orchard, and difficult to
manage next year. Monitor for sustained moth catch and follow recommendations on pages 40, 42, 43, and 46 of Pub. 360. One or perhaps two insecticides may be required if mating disruption has not been applied.

Indirect pests like European red mite can be controlled by predators if insecticides are
reduced. Monitor for both European red mite and beneficial insects to decide if action is necessary, but don’t let populations explode. Trees can tolerate a higher mite population under low crop load. If oil was applied before egg hatch, season-long control may result.

Young trees should be monitored for leafhoppers, aphids, apple leaf curling midge and
Oriental fruit moth (which can deform trees).

With the reduced crop load, vegetative growth may be excessive. Summer pruning will be required to check this growth. This cultural practice will open up the canopy for good air circulation for disease management and allow spray penetration into the tree.

In areas where only partial crop loss has occurred, and some fruit will be salvageable through spot picking, a regular pest management program should be maintained.