I am sorry for this delayed reply to your gardening question. The spring rush has brought a deluge of questions and we are working hard to catch up!
Your tomatoes are apparently being attacked by some type of fungal disease. Your best bet is to take some leaves and vine sections showing the damage to your County Extension Office and see if they can identify the cause of the damage. They would then be able to recommend an appropriate, labeled product for you to use.
Thanks for the question. Best wishes for a wonderful gardening season. Please stop in again soon!
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