Apply dormant spray to fruit trees after the leaves fall off, usually in the late fall. The spray should then be reapplied two to three times throughout the winter.
Spraying fruit trees with a dormant spray helps protect them against disease spores that get blown by the wind. The best time of day to apply the dormant spray is when there is light to no wind and when there is no immediate threat of rain. The most important time to apply another coat of dormant spray is in the late winter, before the tree forms buds. Applying the dormant spray while the tree is budding can kill the bees that help pollinate the tree.