I would not recommend using a pesticide on your fruit trees in May. There is too much of a risk to the bees that would be pollinating the blossoms. You can clean up debris and lay a fresh mulch at the base of the fruit trees and once the fruit forms cover the apples with nylon stocking booties to prevent apple scab but a dormant oil spray used in winter is the safest way to help prevent insect and plant disease in your home orchard. Keep growing, Marianne Binetti