Agrobacterium species were first classified by means of a pathogenicity based-taxonomy in A. tumefaciens, those strains that induce crown-gall. This bacterium has the widest host range of any plant pathogen. It is capable of causing tumors, or “galls,” on virtually all plant species, except the monocots (grasses).
Galls are most common at the bases of canes or on major roots, but they occasionally form on branches higher in the bush. It can cause severe problems on blueberry. These galls may be scattered in discrete masses on infected roots and branches or they may occur in long linear strips of contiguous bumps. Galls can also completely encircle the branch.
In blueberry, strains of Agrobacterium biovar 1 (i.e., Agrobacterium tumefaciens species complex), R. rhizogenes, and A. rubi were reported as causal agents of the disease.
Crown gall of blueberry plants
