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 root-producing structures develop on aerial parts of certain apple trees.Continue reading “Burr Knots, What Are the Root-Like Growths on Apple Tree Trunks and Branches?”
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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, almonds, cherries, peaches, pears and apples. These disease-causing bacteria liveContinue reading “Crown Gall, What Are the Brown Growths on Apple Tree Trunks and Branches?”