Protect Trees and Shrubs with Dormant Sprays
By: Julie Day
Winter is a good time to get a leg up on pests and diseases through the use of dormant sprays. Dormant sprays are applied to deciduous trees and shrubs after the leaves have fallen and the plants are dormant.
About Dormant Sprays
Dormant sprays kill overwintering insects and fungal diseases that can threaten the plant next spring.
Because the pests have limited hiding places in winter, organic dormant spraying can reduce the need for more harmful treatments and sprays during the growing season.
Dormant sprays are most often used on:
- Fruit trees
- Other deciduous trees or shrubs that struggled with infestation or disease during the previous growing season.
Types of Dormant Sprays
There are three main types of dormant sprays. In general, all three types are considered organic, but be sure to check the label before using, since some dormant sprays are mixed with non-organic pesticides.
- Dormant (horticultural) Oil: Dormant oil sprays work by coating and smothering overwintering insects and eggs. Dormant oil can be used to control pests such as aphids, scale, mites, twig borers, white flies, and leaf rollers. Dormant oils are generally nontoxic except to insects. Since they work by smothering insects, the critters can’t build up resistance. The most common dormant oils, such as Volck oil and Bonide, are petroleum based. Others, including Oil-Away Supreme Insecticidal Oil, are plant based. Dormant oil can also be used as a base mixed with other insecticides or fungicides, to make them stick and work better.
Dormant Spraying Tips
- Spraying Safety: Even though they’re organic, dormant sprays can be irritating to skin and eyes. Wear long sleeves and gloves, and use eye protection and a mask when applying dormant sprays.
- Dormant Spray Guide (J&L Garden Center)
- Dormant Spray (Bayview Farm and Garden)
- Using Organic Fungicides (Planet Natural)