Crown Gall

Pest: Crown Gall (Agrobacterium tumefaciens)

Pest Type: Infectious disease, bacterium

Major Identifying Features: The crown gall bacterium causes distorted growths or galls on bark on the basal stem and root crown, at the soil line or just below the surface, galls also develop on limbs, trunks, and roots, crown galls are softer than normal wood when cut and lack the annual growth rings, can be small or massive in size

Life Cycle: The bacteria reproduce in galled tissue and may slough off and survive in soil for long periods, bacteria in soil enter plants through wounds, bacteria can also infect newly emerging roots, growth cracks, and wounds caused by sucker removal or equipment

Pest Rating: Minor to moderate

Management Rating: Moderate

Host/Season/Outbreak Information: Can occur anytime

Damage Information: Many plants can be infected, especially euonymus, fruit and nut trees, Prunus ssp., rose, willow, chrysanthemum, dahlia, geranium, marigold, peony, snapdragon

Management Options: Prevention by solarization of the soil before planting, disinfecting roots in nursery before planting out, cultural practice by cutting out the galls and exposing the tissue to drying, and planting resistant species (e.g. birch, cedar, coast redwood, holly, incense cedar, magnolia, pine, spruce, tulip tree, zelkova) mechanical control by replacing trees with galls if their growth is unsatisfactory



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