Is this stem rot? Help!!!

I notices over the last week or so, that one of my plants G13 Haze 6 weeks into flowering, started showing brown on the stems, I noticed that the buds have started to brown and fall off easily, is this stem rot, and is the only way to cure it to cut it off? any help appreciated. Pic posted.

I didn't know that could happen to a MJ plant. I had to post something so that I could follow this thread.