My tomatoe plants are 2 months old, 4-5 feet tall and loaded with fruit. But now one of them has begun yellowing on the new growth starting at the base of the leaves growing outward. They're in a 12" raisded bed and watered 20 minutes 3x week with drip system. Except for this new yellowing they seem to be very healthy. Been looking at pics on the net and haven't found any that look like mine.

Anybody?????

I would put a pic but I don't know how. :-(