Tag: crown gall

Burr Knots, What Are the Root-Like Growths on Apple Tree Trunks and Branches?

burr knots on apple trees

Burr knots (burrs or burls) are masses of small root initials, plant cells that are dividing and transforming into root tips, which appears on the above-ground portion of a rootstock, or on the trunk and limbs of apple trees. This is an inherited disorder where […]

Crown Gall, What Are the Brown Growths on Apple Tree Trunks and Branches?

Crown gall is a bacterial disease caused by Agrobacterium tumefaciens (syn. Rhizobium radiobacter), which produces tumour-like swellings on the bark of trees and plants. It can infect a wide range of dicotyledonous (broad-leaved) plants, particularly members of the Rosaceae (rose) family such as roses, raspberries, […]