Question
I have several roses that are hardy and come up beautifully, branch out and bloom and one of the blooming branches will just fall to the ground and fall off.  It is healed at the base of the plant - brown and cleanly scabbed.  The healing off is a is a process that gradually breaks the branch off, it usually happens to one branch at a time.  One answer I received was that it was a nitrogen defiency caused by my using raw wood mulch 3 years ago but I spread urea around the plants and it still seems to be happening.  Any ideas?

Answer
Sounds the the brown healing you are describing may actually be a fungal canker.  The canker will form and slowly grow around the stem and then the branch will die when the water conducting tissue is cut off by the fungus.  Look in the cankered area and see if you see concentric rings formed on the inside.  If so, it would definitely be Alternaria stem canker, which is common in roses.  Several rose fungicides will help to prevent spread of the disease.  Your local garden center will be able to help with specific products.  Good Luck.