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 tru…
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. It’s not a disease, but it can be a problem!