Before fruit trees leaf out in spring, before the first signs of aphids, powdery mildew or obscure scale, home orchardists can undertake an important control step to minimize pesticide use later in the season. Application of dormant oil is highly recommended in the Klamath Basin for most fruit trees. Dormant oil, a preventative pesticide used both in organic and conventional production, is used against piercing-sucking insect pests, mites, and even some plant diseases.