Kay Kawashima of Sunshine Nursery in San Jose agrees. It knocks out aphids, scales, spider mites and whitefly. Dormant spray should be applied to all deciduous trees and shrubs, but especially fruit trees and roses. It's better to spray late than not at all. The point is to have the sprayed material on the tree throughout the dormant season, and especially at specific pest-growth periods.
Complete coverage is essential for effective control of overwintering pests.
This disease can weaken the tree and interfere with blossom and fruit production. It's necessary to spray during leaf fall in late November or early December, and at bud swell stage in mid- February. Garrison says some gardeners are successful with only one application during the period of early December through late January. But if the leaf curl was very bad on peaches and nectarines the previous season, two sprays would be the best bet. Remove all mummies and spray the ground.