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What is Dormant Oil and how can it protect my Trees on Long Island

What is Dormant Oil?

Sometimes also referred to as horticultural oil, dormant oil is a mix of petroleum oil and water. It is applied directly to the plant or tree to prevent and eliminate any soft-bodied insects, such as aphids, mealy worms, thrips, whiteflies, mites, and scales from infesting your trees and shrubs over the winter. It is not poisonous or harmful to humans or outdoor pets. It will not hurt any fruit that may grow on fruit trees and is safe for both the environment and wildlife. Instead of poisoning the targeted pests, it creates a layer of thin film, which covers their breathing tubes and eventually kills them.

Specific Pests Dormant Oil Targets Here in Long Island

There are many different species of insects that attack our Georgia trees and shrubs. Some of these insects are so tiny; you may not know they are there. They often live on the underside of leaves. Dormant oil typically targets two types of insects, sucking pests and chewing pests.

Sucking Pests
One such group of pests are what we call the sucking pests. This is because they use their piercing mouthparts to suck the sap from your trees which distort plant growth. In sucking out the sap, they leave behind a sticky substance that looks like a black fungal growth on the upper leaf’s surface. Common insects that fall into this category include aphids, scale insects, mealybugs, lace bugs, whiteflies, and spider mites. Symptoms of sucking pest infestation include:

  • Wilting of plant tissue
  • Stunting, curling, or distortion of new growth
  • Yellow, withering leaves
  • Damaged twigs and branches
  • Black sooty mold on your patio furniture or other landscape surfaces

Chewing Pests

leaves with insect holes
These types of pests cause damage to your beloved lawn ornaments in multiple ways. They like to feast on your plant’s leaves and stems and borrow in the plant’s tissues. Pests in this category include tent caterpillars, fall webworms, bagworms, and beetles. Symptoms that your plants suffer from the damage of chewing pests include:

  • Holes in leaves
  • Silvering of leaf tissue
  • A rusty red color on leaves
  • Complete skeletonization of leaves altogether

How Can Dormant Oil Help Protect Your Long Island Trees and Shrubs?

So how can dormant oil help? Dormant oil is applied to the branches and twigs of trees and shrubs in the fall before these pesky critters start to overwinter. It can be highly effective at preventing an infestation because the application either suffocates or blocks these pests’ breathing pores, stopping them in their tracks. There are homemade versions of dormant oils, or you can purchase dormant oil at most home goods and garden stores. However, knowing the right amounts to use and choosing the correct oil is essential. Different trees require different types of oils. An apple tree requires a different mix and amount than an oak tree and so forth. Because of this, we recommend calling in a local tree care professional who knows your local climate, the different types of trees native to your area, and who have been trained on how to use and spray applications of dormant oil.