Crown Gall of Stone Fruit

Two distinct forms of tumour-inducing bacteria have been isolated_ One form, readily isolated when macerated galls were plated on Patel's medium, did not grow on Schroth's medium even when antibiotics and other bacterial inhibitors were omitted; nor did it produce 3-ketolactose when grown on lactose agar_ It is considered to be the primary cause of crown gall in at least one commercial nursery_