What is Horticultural Oil?
Horticultural oil is made from refined petroleum, which can be mixed with water for pest control application. The use of horticultural oils can be an effective alternative to conventional pesticides. They not only work just as well but are safe for the environment, humans, and most animals. Generally applied as a spray, this type of pest control works by suffocating insects and their eggs. Horticultural oils may also deter pests from laying eggs and protect plants from viral or fungal diseases. While horticultural oil is considered safe to use, it can be toxic to fish and may adversely affect beneficial insects, like ladybugs and honeybees. Some plants do not tolerate these oil sprays either. For instance, plants with blue-colored foliage or wax-like coatings should not be sprayed with horticultural oil. Horticultural oils are most effective for treating aphids, whiteflies, spider mites, scale insects, and other soft-bodied pests. Complete coverage of the foliage will increase its over
Essentially all commercially available horticultural oils are refined petroleum products. Homemade recipes that include vegetable oils also can be used. The type of vegetable oil however can greatly affect its effectiveness. Cottonseed oil is generally the most insecticidal of all the vegetable oils. There are two types of oils used for pest controldormant oils and summer oils. Dormant oils are applied when the plant is dormant (winter). These oils have a high viscosity, or heaviness. This is important because during the dormant season, insects and mites have a lower respiration rate. The heavier oil is slower to dry and therefore covers the pest for a longer period before evaporating. This increases its effectiveness. Summer oils are lower viscosity, lighter oils. Usually, an emulsifier has been added to ensure that the oil mixes well with water to ensure uniform spray coverage. Summer oils are applied during the growing season. Summer oils are known by many names including ultra-fine
There are two kinds of oil used for pest control. For a century, various oils have been used to control unwanted insects, fungi and mites on fruit trees and woody ornamentals. These oils, known as dormant oils, are heavier oils, and are applied during the winter (dormant) season only. Todays newer horticultural oils are lighter and more highly refined. They may be made from petroleum products or plants. Often called ultra-fine, or summer oils, they can be applied to actively growing plants and plants in full leaf throughout the growing season How do they work? Horticultural oils work in several ways. They block the insects breathing holes, causing it to suffocate. Oil interferes with the cell metabolism in soft-bodied insects like aphids, scale, lace bug wooly adelged, mealybug, whitefly, and some caterpillars. Oils can disrupt the feeding patterns of certain disease carrying insects and can even kill overwintering insect eggs and fungal spores. For more information: “Horticultural Oil
