Some years back I bought a thompson seedless grape. It turned out to be a purple variety. The grapes would form, then flower. They would then get a white powder on them and die. I thought they were out of their environment. I then purchased another thompson. It did the same thing. My neighbor down the street gets grapes. I thought I might be pruning them wrong as well. Is there something I need to do to get grapes? Or is there something I am doing wrong? I live about a mile from the coast. I have since purchased two different varities that are specifically for the coast. I dont want to spend a lot of time and effort on these only to have the same problem. I appreciate any input you give me.