Burrknot

Burrknot is a tree disorder caused by the formation of adventitious root primordia.

[1] It first looks like a smooth orange bulge growing from the stem or a branch.

[2] At onset it begins to look like a smooth orange bulge growing from the stem or a branch, later, during one to three years, multiple adventitious roots begin to form.

[1] When located on the roots, it is considered to be not very dangerous, but it makes it easier for diseases to infect the tree, and leaves it more susceptible to insects.

[4] It is recommended to protect trees from moisture and shadow at the burrknot location, and to prevent infestation by synanthedon myopaeformis.