Crown Galls

Plant disease caused by a bacterial infection which leads to gall development on stems or root crowns. Extensive research has been conducted about this bacterium over the past 80 years as the plant can integrate parts of its DNA into a plant’s genome, turning plant cells into tumor cells. The bacterium can survive in free-living state in a variety of soils, or on roots.

Latin Name

Agrobacterium tumefaciens

Trees Affected

140 genera and 90 families of woody shrubs and herbaceous plants

Threat to Trees

Minimal to Moderate


Several weeks before galls manifest, requiring adequate temperature, humidity, and overall growth. Gall size increases until it becomes too large to obtain sufficient nutrients, at which point it dies, releasing bacteria back into the soil which remains active for a minimum of two years.


Bacteria enter through small wounds. Transmission occurs through any variety of methods, including insects, bugs, humans, splashing rain, soil, etc.

Signs & Symptoms

Relatively large galls forming at the soil line, on roots, or above ground on stems and twigs. Young galls are smooth and spongy and harden as they get woody and hard.

Domestic Origins


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