Hi Timothy:  Can you please send images of the whole tree so we can try to identify what kind of tree it is?  Are you able to provide more info. about the care/maintenance/age of the trees by filling out the following form - https://www.uvm.edu/sites/default/files/Extension-Community-Horticulture/UVM_Extension_Master_Gardener_Helpline_Intake_fillable_form.pdf This information will help us to provide a more accurate diagnosis.  Thank you.  

Hello Timothy:

I received confirmation from the Plant Pathologist that this looks like apple scab, the most common fungal disease of apples and crabapples. The fungus overwinters on fallen leaves and in the spring the spores are discharged and land on new emerging leaves, causing an olive brown leaf spot. THis is the disease commercial growers spray 15-20 times a season for. Since most backyard apples do not get sprayed that much (for good reason!) pruning the tree to provide good air circulation so the leaves dry quickly is a good practice. Also cleaning up fallen leaves in the fall since that is where the pathogen overwinters. Here is more info on the disease and its control. https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/insects-pests-and-problems/diseases/scabs/apple-scab

Your very welcome, Timothy!