Answer: There are a number of diseases wchich affect tomato plants, so it is impossible to give you a definite identification of the problem without seeing the plants. However, it sounds like they may be suffering from late blight. This begins at the base and works up the plant, first with the older leaves yellowing and developing what almost looks like black, irregular, water-soaked patches. Unfortunately, there is no cure and the infected plants should be dug up and removed from the garden along with all debris to avoid spreading it to other plants. But before you do that, I would suggest you take a sample to your County Extension for a positive identification to make sure that is what it is. In Montgomery County, their telephone number is 489-4315.
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