We planted four pumpkin seedlings in May from two different sources.  One of the plants had spots on the leaves but it grew normally and it did not seem to be affecting anything. It didn't really fit the criteria for powdery mildew because the leaves looked more like a separation of the top and bottom layers with no evidence of insects like leaf miners.  Each new leaf had that blister look. However the fruit it started making was abnormal so we cut out the vine and now a couple of the other plants are showing the same thing on new leaves. They have well-developed pumpkins and we hate to cut those out. Is this something we can treat with a copper or sulfur solution?