The other day I was walking along through the vineyard and saw some muscadine mummies left on the vine after pruning. This is not a good practice to leave this material on the vine, especially when we are starting the growing season. Previous research has shown that mummified, diseased berries in the canopy area are much more likely to infect new berries than if the old berries are dropped to the vineyard floor. The best option is to remove them from the vineyard entirely along with the pruning material. See the photos below on what a mummified muscadine berry looks like.
North Carolina State University has been a leader in Muscadine pathology with Dr. Turner Sutton and Bill Cline. Here is a good online fact sheet written by Bill Cline: http://www.ces.ncsu.edu/depts/pp/notes/Fruit/fdin012/fdin012.htm