It looks to me (based on the single photo) like one of the leaf spots,
like bacterial spot or septoria spot. Remove the badly infested leaves
and use a copper spray on the plants. I'd also suggest using a kelp
(such as Maxicrop) in your foliar spray. The extra potassium and
micronutrients would be valuable. (I'm looking at the illustrations
in _Identifying Diseases of Vegetables_ published by Penn State.)
Try looking at the photos here and see what you think:
(And please, no poetry!)
Pat in Plymouth MI ('someplace.net' is comcast)
Any technology distinguishable from magic is insufficiently advanced.
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