Symptoms and damage
appearing as galls on roots and at the base or "crown" of
woody plants. Crown galls are also formed on ornamental woody crops such as
roses, Marguerite daisies, and Chrysanthemum spp. as well as on vines and canes
such as grapevines and raspberries.
Marguerite daisies, chrysanthemums and grapevines can become infected
systemically. Occasionally, galls have been observed on field crops such as
cotton, sugar beets, tomatoes, beans and
alfalfa , but the disease does not impact such crops economically. Crown gall
is caused by Agrobacterium tumefaciens, a Gram-negative, bacilliform bacterium
that is normally associated with the roots of many different plants in the
field. This bacterium can survive in the free-living state in many soils with
good aeration such as sandy loams where crown gall diseased plants have grown.
The bacterium can also survive on the surface of roots (rhizoplane) of many
Eradication of crown gall
using creosote-based compounds, copper-based solutions, and strong oxidants
such as sodium hypochlorite are transiently effective. The chemical eradicant
application procedure is labor intensive and therefore costly both monetarily
and to the environment. The superficial treatments are ineffective against
systemically infected plants. Generally, chemicals are rarely used for control
of crown gall.