When were they planted?

And are they in pots or in the ground?

Can you post pictures?

Sounds suspiciously like verticillium wilt. Both maples and smokebushes are quite prone to it. Posting pictures could help. Cutting off a dead branch that emerges close to the trunk and describing its surface or photographing it could help as well.

I am sorry I cannot post pictures, I can barely get on line these days. The brances look just like they died from lack of water. Both maples are fairly established, they have both been in the ground for over 5 years, both have done well until this year. Gardengal if it is verticillium wilt is there anything I can do to keep it from spreading?. Thanks for the info. Lynn

As verticllium wilt is a soil borne fungal organism that is present in most soils, it is pretty hard to control. It is an opportunistic pathogen that can remain inactive for many years and then become stimulated into activity as a result of various plant stressors, like drought, poor drainage, root disturbance, etc. And it can be easily transmitted to other susceptible plants through contaminated tools like pruners or cultivators/weeders.

The best prevention is good cultural conditions. If you can keep plants free from stress by offering the best soil conditions, assuring good drainage, adequate watering and avoiding root disturbance or excessive fertilization, you can often avoid a lot of problems. And clean and sterilize your tools after use and between pruning different plants.

If you've lost a plant to verticillium - and that can be confirmed by taking a sample to your local extension office - you want to avoid replanting with a susceptible species. Google searches will provide listings of plants known to be resistant.

Here is a link that might be useful: info on Verticillium wilt

I noticed tonight that each of my 3 15-year old maples are in trouble. The leaves are curling and there are lots of black spots on the yellowing leaves. My neighbors' maples are all doing the same. Could it possibly be because we had so much rain this summer? We had huge amounts of rain in New England through July.