Released by the Washington County Extension Office …
Currently, growers are harvesting lettuce, broccoli, cabbage and other winter vegetable crops, and not thinking about spraying fruit trees and berry bushes for insects and diseases. February is prime time to apply dormant sprays to aid in the prevention of insect and disease issues later. In fact, the recent warm weather has triggered fruit trees to begin blooming, so if growers intend to apply dormant sprays, they must do so soon.
What are dormant sprays?
Dormant sprays are applied to control insect and disease pathogens during the winter season. Many insects overwinter on trees and shrubs, either as eggs or immobilized in a protective shell (scale insects). Many fungal or bacterial diseases overwinter on last years’ foliage or on stems and branches.
Horticultural oils, Sulfur and Copper all control different insects and pathogens, but can be applied during winter dormancy. Horticultural oils work by smothering the eggs of some insect species or encapsulated scale insects. Since they cannot breathe, they die.
Sulfur compounds kill dormant or latent disease spores, and copper compounds kill bacterial cells that cause canker or fire blight.