you might get better answers than this, but now having seen the leaves, i would recommend cutting the leaves off between the rot and the crown, leaving plenty of healthy space. and i would do it soon. look at the crown (the base of the plant going into the roots) and see if it has a lot of black around it. if so, you have crown rot. let me know if you see crown rot. there are a couple of online growers who give real good, easy to understand advice.
thank you for the advice. i have done this in the past, but wondered if there was another solution. i will check the crown. these plants have existed for quite some time with these black spots. at first i thought they might have been sunburn, although as i watched the plants the spots grew. it confused me because it was dry. i correlate rot with wet. thanks again. d.