Abstract
Five Libyan isolates of agrobacterium radiobacter, as well as the references strain k84 were tested for their in inhibitory effects against a local pathogenic isolate of agrobacterium tumefaciens (AT-B) and the standard pathogenic strain (FACH). In antibiosis assays in-vitro, the non-pathogenic isolate designated (AR-A) inhibited growth of A. Tumefaciens (AT-B), and (FACH) as indicated by no growth of either pathogen in the zone of inhibition. Similarly gall formation on carrot disks, castor bean and tomato seedlings was completely inhibited when the antagonist (AR-A) was applied prior to inoculation with the pathogen.