Dormant oil sprays provide gardeners with an effective and environmentally friendly way to control insects on fruit trees. In addition, dormant oil can be made at home with common household ingredients. If made correctly, a homemade dormant oil spray is just as effective as any commercially produced variety. Furthermore, there are different recipes available for use in treating specific insect problems.
All-Purpose for Soft-Bodied Insects
To control soft-body insects like aphids, mites and mealybugs, all you need is canola oil, laundry detergent and water. Mix together 1 tablespoon of canola oil, a few drops of laundry detergent and a quart of water. Shake well and pour the mixture into a spray bottle when you are ready to use it. This mixture controls insects by smothering the insects, so make sure to use an adequate amount when applying it to your fruit trees. In addition, this solution may be used as a preventative spray that works by smothering insect egg casings.
Fruit Tree-Specific Spray
A more refined solution for use with fruit trees can be made similarly to the all-purpose solution above, but with a few exceptions. Start by mixing together 1 cup of vegetable oil and 2 tablespoons of liquid soap. Take the oil/soap mixture, and pour it into a gallon of water. Shake the solution well before and during use. This concoction is specifically designed for use when the tree is dormant to suffocate insect eggs on the fruit trees. Furthermore, most commercial dormant oil sprays are made with refined petroleum so this homemade mixture provides a much less toxic substitution.
Sometimes insect control requires a different approach than suffocation. Another method for controlling insects on fruit trees is to apply a spray that deteriorates the waxy outer coating of the insect, thereby exposing it to the elements, which causes its downfall. To make a dormant oil spray for fruit trees that accomplishes insect control via this method, start by mixing 5 tablespoons of hydrogen peroxide, 2 tablespoons of baking soda and 2 tablespoons of soap (preferably of a natural origin like olive oil) with 1 gallon of water. Pour the mixture into a sprayer and shake it vigorously before applying it. The baking soda and hydrogen peroxide are an important part of this solution because they work to sterilize fungal spores that are potentially damaging to fruit trees. This spray is also great for use after pruning as a way to seal the tree and keep unwanted pests out.