There is a root rot that infects roses called Armillaria and roots become mushy and rot away - I have not heard of the root fungi causing \"seed pearls\" on the roots so perhaps what your roses are suffering from is a different disease. Root rots are encouraged by poor drainage and too much water. The only way to get rid of Armillaria is to fumigate the soil which is not practical for the home gardener. You may need to remove the infected roses and build a raised bed on top of the original soil. Planting in a berm of fresh soil will ensure proper drainage but I cannot promise new rose plants would not also get the infection. Perhaps growing a different type of plant in this area is the answer. Marianne Binetti