Dear Flazen,
Thank you for reaching out to "Ask the Extension" regarding your nectarine and cherry trees and especially for providing photos of the problem you are experiencing.
I have a couple of questions for you first before we investigate what is occurring here.
1. Have you noticed any insect activity such as holes or eggs at all on your trees or the underside of the leaves?
2. Do the leaves feel sticky at all or look dirty?
3. How often and by what method are you watering the trees? Are sprinklers spraying at the base of the trees or does water spray the trees from above?
4. Have you ever had your soil tested?
5. Did you notice problems with your cherries last year?
I look forward to hearing from you soon!
Laurie W.

Thank you for contacting "Ask Extension" about your fruit tree problems. In cases like this, the issues can be multifactorial and present a confusing picture, and just as in human health issues, sometimes it becomes a process of elimination.
1. In peach and nectarine trees nitrogen deficiency can cause red spots to form on the leaves which then die and fall out causing a "shot hole" condition. If this is the case, you will see the damage on the entire tree, not just one area. A soil analysis will be able to tell you if your soil needs conditioning. Here is a link to the OSU soil testing laboratory. https://cropandsoil.oregonstate.edu/shl/testing-services/soil-testing 
2. Bacterial spot is a primary disease of stone fruit trees. Symptoms start as small reddish spots which as the disease progresses gives the leaves a ragged look. Bacterial spot is more severe in trees grown in sandy soils and stressed trees.  You had mentioned that you sprayed your trees with copper which is a recommended treatment measure. I'm not sure if you only sprayed the cherry tree or if you sprayed the nectarines as well. Nectarine trees are extremely sensitive to copper which can result in leaf damage that resembles the actual disease it is meant to prevent.
Treatment options include: 1.) Early season pruning to control tree vigor, improve air movement and sunlight penetration. It also helps improve coverage of the copper spray. 2.) Plant bacterial spot resistant varietals. 3.) Fertilize and apply chemical sprays in the dormant season according to recommendations, usually the fall is the best time after the leaves have fallen. 
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As for the Cherry tree leaf curl, the black cherry aphid is a likely suspect. It infests the leaves, sucking out the juices resulting in the curling appearance, then deposits honeydew creating a sticky feel to the leaves. The honeydew can also support the growth of sooty mold fungi, which can reduce the amount of sunlight reaching the photosynthetic cells of the leaflets, potentially injuring the tree's vascular system and reducing chlorophyll development and leaflet size
Management is most effective early, right after bud break. Once leaves curl, the aphids are more difficult to control as they are protected from chemical sprays. 1. Monitoring: Regularly check the tree for aphids, especially during periods of rapid growth. Early detection can help prevent the aphids from reaching high populations.
2. Biological Control: Encourage natural enemies of aphids, such as parasitic wasps, lady beetles, lacewing larvae, soldier beetles, and syrphid fly larvae, which can help control aphid populations
3. Ant Management: Since ants tend aphids and protect them from predators, controlling ant populations can indirectly help reduce aphid numbers. You can use sticky materials like Tanglefoot around the trunk of the tree to prevent ants from climbing up.
4. Cultural Control: Prune out aphid-infested areas and dispose of them, and avoid using excess nitrogen fertilizer, as it can promote aphid reproduction.
5. Physical Removal: If the infestation is localized, you can manually remove aphids and their honeydew from the tree.
6. Chemical Control: If necessary, you can use contact insecticides like insecticidal soap and horticultural oils, which are less damaging to natural enemies compared to other pesticides (Remember to apply any pesticides carefully, following label instructions and considering the potential impact on beneficial insects)
The good news is that these problems rarely kill the trees, I hope this helps. Happy Gardening!
Laurie W.