We have been growing tomatoes for 10+ years, but this year we have something horrible that is destroying our tomato plants. One problem is that the plants are shriveling up - the leaves first develop dark spots and then they shrivel to nothing. On one plant the tomatoes had a huge, canker-like sore. Does anyone know what this might be? And/or how to prevent this from happening in the future? FYI, we grow our tomatoes in raised beds, use organic materials and compost. Any help is GREATLY appreciated!