Question
I live in Zone 6.  I have a problem with my roses that I have not been able to find in any of my books.  When I prune or dead head, I quite often find a hole in the center of the cane which looks like I might have bores, but if I continue to cut both ways a 1/4 of an inch at a time I don't find a borer.  I find that the center of the cane is soft and discolored.  If I continue to cut back the center of the cane will eventually get firm and white and healthy looking.  In the spring, my plants look great and grow like mad but I always have a lot of canes that turn brown, drop their leaves and die.  I believe that this is due to my cane core rot problem.  I have 32 rose bushes and this condition is most prevelant in the Hybrid Teas and the Floribundas.  I don't see it much in the shrub roses.   Thanks for your help.

Answer
You rarely see the actual insect - you just find the result of the insect putting its larvae inside your rose canes. The larvae eat out the innards of your rose canes, leaving you behind a hollow cane. Because they are most active causes damage in the summer, over the winter is when the rot sets in which is caused by bacteria. These bacteria like it cool not warm or hot. So when you go to war, it is a wisdom to know the enemy.
Cane borers lay their eggs in the spring so pruning in the fall or very early spring is a good idea. Then you can seal the cut off (Elmers glue is rated as the best sealant) or vaseline. What ever method you use, adding food colouring to it helps to keep track of the canes you have cut. They also prefer hybrid teas and don't pay much attention to the old garden roses and modern shrubs as their canes are usually tougher. Plus some hybrid teas and floribundas are particular prone to cane borers.
Dead heading by just snapping the flower off or cutting close to it's base, stops making an opening for the borers. Plus it has been proven to be much better for the rose than cutting back to the first 5 leaves. The rose gets more leaves to make food with and you don't have to wait for flowers until the canes grow back from the cut.
There is another insect that just makes a hole in the cane's end and that is the Carpenter bee. This little bee eats ten times it's weight in bad bugs and only uses the hole as a motel room. Hope this helps. Lynnette