Many of the leaves of my tomato plants have started turning yellowish/black/brown and seem like there is little/no water content in the leaves. It is happening on all different kinds (sungolds, brandywine, romas). I still have fruit on some of the plants so I'm wondering if it is a fungi or if they need something like nitrogen. We've been watering regularly...from the bottom, not on the leaves. Any help would be appreciated.
I'm by no means an expert, but that's happened on some of ours too, yet the fruit is still good -- I guess I just assumed that the plants were shunting all their resources to the fruit, and letting the leaves go. Could that be?