North American Fruit Explorers mailing list at ibiblio

[Pete Tallman <pete_tallman@hotmail.com>]

The flat stem condition is called fasciation; Gina Fernandez at UNC did a 
short article on it last spring at 
http://teamrubus.blogspot.com/2012/05/fascinating-floricane-fasciation.html

More general writeup from Colorado State is at
http://www.coopext.colostate.edu/TRA/PLANTS/fascia.shtml

If you don't need the plant, my tendency would be to take it out. 

I've only seen this once on my own stuff, but that was on one primocane on a 
plant that was on its way out anyway. 

Pete Tallman
Longmont, CO    zone 5 or so