Question
tree growth
I was hoping you could help me identify this growth/bark deformity. The entire tree is covered in them so I was thinking that it may be caused by some type of infection. I have no expertise in plant physiology and was hoping you would be able to point me in the right direction. Thank you
AnswerThese are called burls or crown galls. Burls are basically benign tree tumors that cause growth with an irregular grain structure. Burls are treasured for their irregularity and the colors associated with this sporadic growth. Burls are used in furniture making.
Crown galls are growths instigated by Agrobacterium tumefaciens, a soil bacteria. These are the burls or 'tumors' that are appear near the base of tree trunks. Sometimes the galls form higher on the trunk, or on branches. The Agrobacterium stimulates the plant host into making the gall. The uncontrolled cell division in the cambium is instigated by genetic material from the bacterium.
The bacteria can live for long time periods in the soil. It is suspected that the bacteria enter the trees through small wounds. The bacterias, seemingly, can be carried on air-borne dirt in the wind. Once inside a tree they insert the gall forming genes into the host, and then multiply as the gall grows.
