American tree spray oil is refined petroleum oil combined with an emulsifying agent to manage certain pest problems (e.g., scales, aphids, mites) on fruit trees, shade trees and woody ornamental plants and also can control some plant diseases, such as powdery mildew. American Tree spray oil has different effects on pest insects. The most important is that it blocks the air holes (spiracles) through which insects breathe, causing them to die from asphyxiation. In some cases, it also may act as poisons, interacting with the fatty acids of the insect and interfering with normal metabolism. This also may disrupt how an insect feeds, a feature that is particularly important in the transmission of some plant viruses by aphids.
When to Apply:
American Tree Spray oil should be used during dormant period of the plant (before bud swelling and bud break) to kill mites and insects, such as scales and aphids, that spent the winter on the plant. Dormant oil applications also control certain overwintered shade tree pests.
How Much to Apply (Dosage):
2 liters of Tree spray oil should be mixed in 100 liters of water and can be diluted further depending upon the development stage of the crop.
Some plant pests controlled by American Tree spray oils.
Dormant Season Applications
• Aphids that curl leaves in spring
• Caterpillars that winter as eggs on the plant (leaf rollers, tent caterpillars)
• Mites that winter on the plant (e.g., conifer-infesting species)
• Scale Insects (e.g., pine needle scale, striped pine scale, Kermes scale, cottony maple scale).
Diseases
• Powdery mildew
• Some aphid-transmitted viruses
