I've been having this later season leaf failure problem off and on for a few years. I have extremely well drained soil on an unusual sandstone bedrock formation, I have been farming the plot for 20 years. I coordinated here a couple yrs ago on some more general yield issues. I had been over liming mainly. This year we had the most regular rains I've ever seen. I have balanced pH now, I use my own compost and fertilize with a little 10-10-10 3 times during season. Staked plants, Black Krim and Big Beef tomatoes mostly. I get big vigorous plants and good fruit production (amount and size) for a couple weeks and then in early august mostly of the plants 1) develop dark spots 3-6 mm in diameter 2) some turn yellow 3) curl up and get grey/brown. all varieties except cherry. Fruits show no signs. Some plants totally die - others struggle on. Am I overdoing nitrogen?