Fruits Affected

Apple, Peach, Plum, Pear, Nectarine, Cherry, Apricot

Also See

Crown gall is caused by a soil-born bacterium, Agrobacterium tumefaciens, and it affects all types of fruit tree. It enters the tree through damage caused by pruning, machinery, winter freezing, insects, and handling.

Symptoms

Gall (warty growth) on roots or lower trunk.

Organic Treatments

There is no known treatment for crown gall once a tree is infected. The best preventative measure is to avoid planting in the same area.

Conventional Treatments

Same as organic treatments.

Disease Cycle

Crown gall is caused by a soil-born bacterium, Agrobacterium tumefaciens, and it affects all types of fruit tree. It enters the tree through damage caused by pruning, machinery, winter freezing, insects, and handling. The bacteria stimulate the tree to produce a hormone that, in turn, causes the tree to form a gall, a growth similar to a tumor or a wart on animal tissue

Crown gall will typically grow on the roots or trunk near the soil line. When it first appears, the gall is light-colored with a spongy texture, but as it ages, the gall becomes dark brown and woody. The gall can interrupt the flow of nutrients to a tree, weakening it and making it susceptible to other infections. It can eventually girdle and kill the tree, especially if it is young, while a mature tree will generally tolerate a gall.

For more information, see the University of Minnesota Factsheet on Crown Gall.