Q. Rosa New Dawn, about 10 years old, has grown well..until now.
Your 10-year old climbing rose has about 1/3 of the canes turning brown and the rest of the plant looks ok. It is probably the older canes that are dying. In any case the cause is most likely the wet summer we have had this year in Philadelphia. The ground is wet, the newer canes can absorb and use the heavy moisture and look healthy. Age is also a factor. You should be cutting out the older canes every few years, but not more that 1/3 each time.