First report of crown gall caused by an Agrobacterium sp. on diffuse knapweed (Centaurea diffusa).
This paper describes the first report of crown gall by Agrobacterium sp. on Centaurea diffusa, first discovered in Mosier, Wasco County, Oregon, USA during July 2004. Pathogenicity tests involving needle inoculation on stems and petioles resulted in gall formation in the following: Acroptilon repens, Carthamus tinctorius, Centaurea solstitialis, Centaurea maculosa, Centaurea cyanus, Crupina vulgaris, Helianthus annuus and Rubus armeniacus. Genetic analyses showed that this organism was a strain of Agrobacterium tumefaciens. This bacterial strain was deposited into the International Collection of Phytopathogenic Bacteria at Fort Detrick with accession number 60099, and the 16S rRNA sequence was deposited into the GenBank database (Accession No. EF687663).