The best way to manage diseases and insects in your orchard is to combine methods. Along with using pesticides, there are cultural and biological practices also that can help prevent or manage diseases and insects. Pesticide timing and thorough spray coverage are the keys to good pest management. For good coverage, wet the leaves, twigs, and branches thoroughly. (Note: This can be difficult with hand sprayers.) When you use wettable powders, be sure to shake or stir the spray mix often during application because the powders tend to settle at the bottom of the spray container after mixing.

To avoid excess chemical residues, be sure to use the correct rate and proper interval between the last spray and harvest.

Here is a terrific publication to help you:

https://catalog.extension.oregonstate.edu/ec631/html