Dormant oil spray is a non-toxic material that can be sprayed on trees and shrubs in the fall after leaf drop or in the spring before leaves or blossoms appear. It smothers overwintering bug eggs before they have a chance to hatch. If you have plants under trees or shrubs you plan to spray, then covering them is a good idea as it can hinder growth of perennials. You can buy dormant oil spray at home improvement stores, discount superstores and nurseries. Apply dormant oil before temperatures drop below 40 degrees F.
Oil-Away™ Supreme Insecticidal Spray from Gardens Alive is made from cottonseed oil that’s extracted the old-fashioned way, by squeezing or pressing. No chemical solvents, normally used in the commercial extraction process, are used. Unlike some dormant oil products, this one won’t burn or harm sensitive foliage if used in warmer weather. IMPORTANT: It’s best used in the fall after leaf drop or in the spring before leaves or blossoms and beneficial bugs appear. Ladybugs and other beneficial insects that migrate onto a plant after it’s been sprayed are not affected.
You can also make your own dormant oil spray:
1 gallon of mineral oil
1 pound of oil based soap (granular form)
1/2 gallon of water
Boil all these and mix well. Dilution rate 1 part to 20 parts water. This home-made dormant oil must be used immediately (cooled of course) as these ingredients separate quickly.