Posted by & filed under Aphids, Insect Control, Mites, Tree and Shrub Care.

Euonymous Scale is one insect prevented with dormant oil.

Now is the perfect time to combat certain insect pests that can damage trees and shrubs later on in the season, with the application of a dormant oil treatment. Most commercially available horticultural or dormant oils  are refined from petroleum oil with the impurities filtered out. This is then combined with an emulsifying agent that allows the oil to mix with water so that the oil can be sprayed to plants.

Older true dormant oils were heavy and could only be applied during the winter.  These have been replaced with more refined, light-weight oils that can be applied to plant foliage year-round without damage. Dormant oils are most often applied during mid-winter to early spring, when plants are dormant. This is a safe yet effective way to control not all insects, but mainly pests such as scale, mites, whiteflies, aphids, and eggs of Eastern Tent Caterpillars.  The oil suffocates the small insects or destroys their eggs, while not harming desirable insects.

Dormant oil is simply mixed with water and sprayed on the stems and leaves of certain plants. Do not apply dormant oil when temperatures are forecasted to drop below freezing within 24 hours. And certain ornamentals, such as Spruce, Japanese Holly, Yew, Japanese Maple, and Eastern Redbud can be damages from a dormant oil treatment during the season. Always read the label before application.

At LawnAmerica, we are applying our T1 Dormant Oil Treatment now. We also add a small amount of systemic insecticide to our mix, which is absorbed by the plants and helps control damaging insect pests as they feed on foliage later during the season. Azaleas are one shrub that this treatment is applied to which does a great job of preventing Lacebug damage.

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