Did your trees and shrubs have a hard spring and summer? Pests and diseases can damage fruit trees and other garden plants. If this is the case, you may want to consider dormant winter spray treatments.
“Dormant spray” is an umbrella term that covers treatments such as horticultural oil, which smother hibernating insects—such as aphids, mites, and scale—as well as their eggs.
Another type of dormant spray uses either synthetic fungicides or copper to treat fruit and flower-bearing trees and shrubs. This treatment can give your plants a head start when going into spring.
Additionally, sometimes liquid lime sulfur will be used on smaller fruit plants such as blueberries or blackberries to kill fungus and bacteria.
Dormant spray application should be after the growing season, but before the weather drops below 40 degrees. While a pre-winter treatment will suppress spring pests, it may not fully control them. Scheduling regular treatments throughout the year may be necessary for the optimal health of your plants.
Common sprays may include:
- A fixed copper fungicide containing elemental copper, such as tribasic copper sulfate, copper oxychloride sulfate, or cupric hydroxide
- Neem oil from the seeds of the neem tree (Azadirachta indica)
- Lime-sulfur is a mixture of hydrated lime (calcium hydroxide) and sulfur
An important step to secure the health of trees and shrubs that may be forgotten by homeowners, whether or not they choose to treat with a dormant spray, is to maintain good housekeeping of plants.
Be sure to remove fallen leaves from the base of plants to prevent pests from laying eggs or hibernating for the winter. The leaves can contaminate adjacent plants, thus hampering success in disease control efforts.