About Crown Gall on Peaches
What causes peach crown gall? Crown gall is a bacterial disease caused by the bacterium Agrobacterium tumefaciens. Typically, the bacteria enter the tree through wounds in the bark, which can be caused by insects, pruning, improper handling, or other environmental factors. Once inside the peach tree, the bacteria transforms healthy cells into tumor cells, and galls begin to form. The galls appear as small, wart-like masses on the tree’s roots and crown, though they can also develop higher on up the trunk and branches. They start out soft and light in color, but will eventually harden and deepen to dark brown. They can be half an inch to 4 inches (1.5-10 cm.) in diameter. Once the crown gall bacteria infects the tree’s cells, tumors may develop far from the original wound, where the bacterial aren’t even present.
How to Treat Peach Crown Gall
Peach crown gall control is mostly a game of prevention. Since the bacteria enter the tree through wounds in the bark, you can do a lot of good simply by avoiding injury. Manage pests to keep insects from boring holes. Hand pull weeds near the trunk, instead of weed whacking or mowing. Prune judiciously, and sterilize your shears between cuts. Handle saplings very carefully during transplant, as small trees can be damaged more easily, and crown gall is more devastating to their health. Antibacterial drenches have shown some promise for fighting crown gall on peaches, but for now, the prevailing treatment is simply to remove infected trees and start over again in a new, uninfected area with resistant varieties.
