Dormant oil is a substance trusted by many gardeners as an organic method of controlling the pests that can ruin a garden. It is simple, inexpensive and easy to apply without worrying about the dangerous effects it might have on the environment or on the individuals applying it. You can make your own by following a few fundamentals.
Understand How it Works
Dormant oil works by coating the pests and their eggs with a thin layer of oil, suffocating them. Because the oil does not poison the pests, you need to spray well for it to be effective. You can use it against aphids, scale, mites, fruit moths and white flies. The term "dormant" refers to the time of application, not to the type of oil.
How to Make it
Because you want to suffocate the pests and not the plants, you have to coat them with a thin layer of oil. If you sprayed with just oil, it would suffocate the plants because the coating would be too thick. Dilute the oil with water, and use a small amount of mild soap to temporarily emulsify it. The ratio of oil to water is 1 cup oil to 2 tablespoons of any vegetable oil, combined it slowly and then add it to a gallon of water. For a combined use as a fungicide, add a cup of baking soda to the mix and shake well.
When to Apply It
Most pests have a life cycle that starts as an egg, but they can lay them more than once a year. Bugs have a hard time living during the freezing temperatures of winter, but as soon as things thaw out, you can count on bugs returning to your garden. Spray in the beginning of spring, coating the trunks of your fruit trees while they are still dormant. Wait until the tree is dry, the air is above freezing and no rain is in the forecast.