Hello,

Using different products at different times of the year is critical to having better control of your pest and disease issues.

Here is a good, recent (2017), resource as a home fruit spray guide from the University of New Hampshire Extension on home fruit trees, which has information about mixing fungicides and insecticides and suggestions for specific targets depending on the time of year.

If you are a home grower you should consider enrolling in MSU Extension's Consumer Horticulture Backyard Fruit 101 course, linked here. They also have articles and other information linked here.

Commercial growers whould consult E-154, linked here, and larger scale home growers would follow regional updates from MSU Extension Fruit & Nuts, linked here. The E-154 fruit management guide has estimated dates, but also degree days, which you can track using Enviroweather (I believe the stations nearest to you are Hudson and Leslie).

Whatever you spray you need to make sure that the product has the crop and target pests in question listed on its label.

Fungi: Early season pests for most fruit crops are fungal diseases like apple scab, cherry leaf spot, rusts, powdery mildew, and brown rot of stone fruit. Fungal diseases continue to be problematic through the growing season. Sanitation during and after the season is key- diseased leaves, fruit, and wood should be removed from the orchard. Fungicides are usually sprayed in clear days ahead of rain because wet weather is usually the prime infection period.

Bacterial diseases: Fire blight (apple and pear) is primarily treated with preventative antibiotic sprays ahead of infection events during bloom.

Insects: Insect pests are relevant at different points of the summer through harvest. These include codling moth, apple maggot, brown marmorated stink bug, spotted wing drosophila, rosy apple aphid, pear psylla, and oriental fruit moth among many others. Insecticides should not be sprayed during bloom in order to protect insect pollinators.

Weeds: The critical weed-free period in apples is from bloom to mid-July. This can be accomplished by mechanical cultivation around the trees as well as by mulches or herbicides.

If you have specific questions about an individual product, pest, or disease that is not covered by one of the above mentioned resources please submit another question.