I apologize that no one has responded to your question sooner. Different experts come online at various times. I just came online and saw your question. My name is ***** ***** I’m a biologist with a special interest in trees. I'm sorry to hear of this problem.
Leaf curl is not a specific disease, but is only a symptom. It can indicate several different problems. However, since it is affecting a dogwood as well as the oaks, there's a good chance it is anthracnose. With this, the leaves eventually start to turn brown and may fall. This is a fungal infection that affects almost all species of trees. It is especially common after a wet spring. It does not kill trees by itself, but if a tree is weakened by something else, anthracnose can be the final straw. Spraying with a fungicide early in spring before any symptoms occur can help control it. It is too late to do that this year. The best thing to do now is rake up and destroy any fallen leaves because the spores overwinter in them. Next spring, you can spray with a fungicide to help prevent a repeat infection.
The limbs dying and coming off the oak would be an unrelated problem. Without knowing what happens to leaves as the branches die, it isn't possible to say what is wrong. There are dozens of conditions that could cause this.However, there are two that are quite common. Oak decline is one. It is a very complex condition and not just a single disease. It affects mature oak trees. There is no treatment, but many trees live for years with it.
Oak wilt is a fungal disease that disease that causes branches to die. The fungus causes the trees root cells to become blocked. Water cannot travel up the roots and the sections of the tree those roots feed will die. The leaves generally wilt before they turn brown and fall. Unfortunately, there is no cure or treatment for this either, and it is fatal.
If you can determine what happens to the leaves on the dying branches, you can figure out what is affecting the tree. Your local Extension Agency may also be able to help. There is no fee for their services, but you would probably have to bring in samples from the tree. If you go to the following site and enter your state, you'll get contact information for your Agency. They could also tell you exactly what is causing the leaf curl.http://nifa.usda.gov/partners-and-extension-map
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