CULT: leaf spot?

Most years, there isn't a lot of leaf spot here, unless the aphid
population is huge early in the season, ahead of the predators.  I don't
treat for diseases (yet) - much more interested in selecting for
cultivars that don't need it.

This year, a few rows have a lot of leaf spot, just showing up this past
week.  It seems to be worse in the rows that were downhill from the most
persistent of the 'artesian springs' (i.e., the whole yard was spouting
water during the floods).  It seems to have 'blossomed' after a week or
so of above freezing night temperatures & sunny days.

I will probably let it run its course, but it has made me wonder about
the ecology of leaf spot.  Does anybody know if there are nutritional
deficiencies associated with plant vigor that are directly related to
resisting leaf spot?  These rows are more sandy than the main gravelly
beds.

--
Linda Mann east Tennessee USA zone 7/8
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