bake them in the oven on some tinfoil, it'll kill any lil bugs or nasties that it might be harboring. i used to do this for a macaw i had. i cant remember the temps & time tho.. hopefully someone will remember & chime in.
*edit*
I did a quick google search and found a post saying for a branch bake 200 degrees for 30-40 mins. but u may wanna look more into the temp & times.
also be sure theres been no pesticides sprayed on it!