Question
Hi Greg,

I have an indoor cactus that was at one time a single stalk which
grew to be very tall ( almost 3 1/2 feet).  Then it grew other
branches off the main stalk.  Recently I moved and had to cut
about a foot and 1/2 off the original stalk.  Now that stalk has
withered and is aparently dying.  All the other branches so far
are still very healthy looking.   I have had this cactus since I was
about 7, its about 35 years old and very important to me.  Can
you please tell me what has happened, and what I can do to help
it.  
thank you very much,
Jeanne-Marie

Answer
Dear Jeanne-Marie,

It sounds like the original stem got infected and rotted after being cut. Generally speaking, if it happened that quickly, it sounds like you have a Euphorbia, not a cactus. Anyway, it would be very helpful if I had a picture of the plant, so I could give you a more complete answer. If possible, send me a picture to [email protected]. It will make a difference if your plant is a Euphorbia rather than a cactus. Thanks.

Sincerely,

Greg