Pests & diseases
The trees are susceptible to a number of fungal and bacterial diseases and insect pests. Nearly all commercial orchards pursue an aggressive program of chemical sprays to maintain high fruit quality, tree health, and high yields. A trend in orchard management is the use of IPM or Integrated Pest Management, which reduces needless spraying when pests are not present, or more likely, are being controlled by natural controls.
Spraying for insect pests must never be done during bloom because it kills pollinators. Nor should bee-attractive plants be allowed to establish in the orchard floor if insecticides are used. Dutch white clover is a componant of many grass seed mixes, and many bees are poisoned while visiting the blossoms on the orchard floor.
Among the most serious disease problems are fireblight, a bacterial disease; and Gymnosporangium rust, apple scab, and black spot, three fungal diseases.
The plum curlico is the most serious insect pest. Others are apple maggot and codling moth.
Apples are difficult to grow organically, though a few orchards have done so with commercial success, using disease-resistant cultivars and the very best cultural controls. The latest tool in the organic repertoire is to spray a light coating of kaolin clay, which forms a physical barrier to some pests, and also helps prevent apple sun scald.