What is Horticulture (Dormant) Oil spray? If you are growing fruit trees, this spray is one of the most important sprays to apply. As the name suggests, it is a spray that is applied during the dormant season of growth which is in the winter or very early spring. (Usually February-March). It is used to kill the overwintering bugs on the tree such as scale, aphids, and mites. There are a few things to be aware of when using a Dormant Oil spray.
Timing is everything! The buds on the tree need to be relatively inactive. How can you tell if a bud is still dormant and hasn’t started to swell? Hopefully these two pictures will give you something to reference. The first picture shows a dormant bud on an apple tree and the second picture shows the bud just starting to swell. The scales on the bud have started to separate to expose some of the inner tissue. You want to time your spray just before the bud has started to swell.
- Spray when temperatures are above 40 degrees F and there is no freeze or rain forecasted but under 60 degrees F.
- Completely saturate the tree. Overwintering insects hide in the cracks and crevices of the branches and trunk. The oil works by smothering the insects and suffocating them – yikes! It will take approximately 2 gallons of spray for an 8-10 foot tree.
There are also All Seasons sprays which can be used at other times of the year.
**Very Important! Be careful not to use those sprays when the tree is in flower. We don’t want to kill any of our pollinators as we need them to set the fruit on the tree.