I've had a Yew hedge for 10 years. A section of it always seemed to lag behind the others. It was suggested that the land slopes and water was collecting and getting root rot. However, that doesn't explain why some that are on the high ground are now suffering from the same thing. What ever it is the Roses are going gang buster from it! The needles turn yellow and fall off starting from the inner branch, moving slowly to the outside. I pulled out 2 on either side of the roses and examined the roots but saw nothing unusual. I've tested the soil for Ph and it is fine. What ever it is is moved from the Yews on either side of the roses and is spreading from bush to bush. Any suggestions?