To check if you have bacterial wilt, cut the end of a wilted vine, put your finger against the cut and slowly pull it away. If strands resembling glue form, you have bacterial wilt.
There's no chemical control for bacterial wilt and the only way to stop it from spreading is to eliminate the vectors, meaning cucumber beetles. The best way to do is by using traps. They aren't cheap (1 trap + 1 lure is about $10 unless you buy in bulk) but they work well and don't affect other insects.
On the other side if bacterial wilt is not present you are probbaly dealing with heat stress, but even during a heat wave I doubt the weather in Cape Cod gets so unbearably hot to affect cantelopes.
