Crown gall is a plant “cancer” responsible for significant commercial losses in almond, walnut, pecan, cherry, plum, prune, peach, nectarine, apricot, apple, pear, grape, caneberry, blueberry, ornamentals (e.g., rose, euonymus, willow, poplar, etc.), and other plants. Infected plants develop expanding tumors (galls) that damage roots and trunks, resulting in weakened, less-productive plants – and sometimes plant death.
In almond trees, galls provide entry points for wood decay fungi that cause trees to “blow down” (topple) during high winds.
The crown gall pathogen is present in almost all soils and infects plants via fresh wounds created during propagation, nursery digging, pre-plant handling, transplantation, and in-field mechanical injury (e.g., grafting, pruning, cultivation).