Question
We have had great luck with our rose bushes as they have been healthy and hardy for several years.  This year they started blooming as always then we notice a white filmy web like substance covering the tops of the bushes.  When touched, it "melted" in your fingers.  It is gone but now our bushes are dying.  What was it and what can we do to save the bushes.  Thank you in advance.

Kim

Answer
I think what you are describing is a form of mildew. Here are the different kinds and their effects. If this isn't it please get back to me.   
Powdery mildew is a white powdery substance that covers leaves. It needs conditions that have high humidity and warm temperature. These types of powdery mildew spores do not need water on a leaf to germinate.They are created when daytime temperatures rise with humidity between 45 and 75 per cent. If daytime temperatures rise to 85? it stops. Downy mildew is the worst type and is a greyish-white fuzz on the bottoms of the leaves, round purple blotches with yellow edges are on the tops. Leaves quickly turn brittle and drop. It is often confused with powdery mildew and black spot, downy mildew can defoliate a plant in one day. It appears after periods of cool, wet weather. It clears when the weather warms. It needs moist conditions to spread, so no overhead watering. Any rose spray with Funginex in it will solve the problem but if it is banned in your country as it is in many, I would try using any copper spray now or a dormant oil and sulphur spray in the early spring as a precaution. An organic spray such as 1 tablespoon of baking soda to 1 gallon of water, helps to make the rose leaves less hospitable to the mildew spores.
When you say your roses are dying, do you mean the canes are going hard and brown or dark and soft? If you are concerned about the leaves falling off, then don't be, as roses can grow three sets of leaves without compromising their vigour.