Burrknot is a tree disorder caused by the formation of adventitious root primordia. Although previously classified as disease, is now classified as a disorder, as it is no longer believed to be pathogenic.
First looks like a smooth orange bulge growing from the stem or a branch, later multiple
adventitious roots Important structures in plant development are buds, shoots, roots, leaves, and flowers; plants produce these tissues and structures throughout their life from meristems located at the tips of organs, or between mature tissues. Thus, a living plant ...
form.
Description
The occurrence of Burrknot is quite common among
rootstock
A rootstock is part of a plant, often an underground part, from which new above-ground growth can be produced. It could also be described as a stem with a well developed root system, to which a bud from another plant is grafted. It can refer to a ...
, often found on apple tree M ( Malling ) and MM ( Malling-Merton ) rootstocks. 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 Important structures in plant development are buds, shoots, roots, leaves, and flowers; plants produce these tissues and structures throughout their life from meristems located at the tips of organs, or between mature tissues. Thus, a living plant ...
begin to form.
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. When many burrknots are present on various location in the tree, it can make the tree unproductive.
Treatment
It is recommended to protect trees from moisture and shadow at the burrknot location, and to prevent infestation by
synanthedon myopaeformis
''Synanthedon myopaeformis'' is a moth of the family Sesiidae and the order '' Lepidoptera''. In Europe it is known as the red-belted clearwing and in North America as the apple clearwing moth. The larvae create galleries under the bark of fruit ...
.
Similar diseases and disorders
A disease somewhat similar in appearance is a
crown gall
''Agrobacterium'' is a genus of Gram-negative bacteria established by H. J. Conn that uses horizontal gene transfer to cause tumors in plants. ''Agrobacterium tumefaciens'' is the most commonly studied species in this genus. ''Agrobacterium'' is ...
.
References
{{portal, Gardening, Trees
Tree diseases