Thank you for your quick responses. The trees were here and appeared to be mature, or nearly so, when I moved here 8 yrs ago, 2002, (south central PA). They were probably planted by landscapers when the house was built in 1998; I do not have any information on their species, origins, age, planting or soil conditions or care from 1998 to 2002. As I mentioned, they appeared to be in good health until the past couple of years. The winters here are cold and snowy/icy - last winter we had epic snow and the winter before was nearly all ice storms; the summers are sometimes dry sometimes wet sometimes both, typically hot and humid; this summer was quite dry for a while then wet. The trees are on a slope along with other ornamental shrubs and ground cover, and they get a lot of sun. There is no mulching around their trunks. I have done nothing to them except keep them watered during draught times, and this spring some large dead branches were removed. It is night time right now, so I could take some pictures during the day and also look more carefully at the leaves and areas you mentioned. Again thanks.

sorry, the post above was meant to be posted to a different subject/thread. i have reposted to the correct thread. again, apologies for any confusion.