How to Use Horticultural Oil for Pest Control

Horticultural oils are particularly useful in the organic orchard where they control pests that overwinter in bark crevices.

| April 24, 2013

  • The recommended practice for applying horticultural oils is to spray trees in spring, just before flower buds open.
    Photo Courtesy Monterey

This article is part of our Organic Pest Control Series, which includes articles on attracting beneficial insects, controlling specific garden pests, and using organic pesticides.

What Are Horticultural Oils?

When applied directly to pests, horticultural oils interfere with respiration, causing insects to suffocate and die. These oils can also kill beneficial mites and cause leaf injury to some plants, and frequent use can reduce yields, even when the pest is controlled. Best applied in cool weather, horticultural oils are valuable tools in the organic orchard, where they can be used to control pests that overwinter in bark crevices. Oily leaf surfaces also make poor sites for insects to lay eggs, and may deter early outbreaks of mites, aphids and scale on fruit trees.

Some horticultural oils include herbal essential oils, which may repel some pests and suppress some diseases. Neem oil is the only horticultural oil considered to be an active ingredient in pesticides.



Highly refined mineral oils, often called superior oils, evaporate quickly so they are less likely to injure foliage compared to heavier oils. Superior oils often control powdery mildew in addition to spider mites, whiteflies and other difficult pests. Only a few products including JMS Stylet Oil and Pure Spray Green are approved for use in the organic production of fruits and vegetables.






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