- a disease of plants, especially of plums and cherries, characterized by black knotlike overgrowths on the branches, twigs, etc., caused by a fungus, Dibotryon morbosa.
Origin of black knot
An Americanism dating back to 1835–45
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for black knot
Happily, black-knot may be controlled by cutting out the diseased wood.The Cherries of New York
U. P. Hedrick
The branches are very liable to disfigurement by the black-knot and the foliage by the tent-caterpillar.Handbook of the Trees of New England
Lorin Low Dame
The fungus is also related to the black-knot fungus on the plum, but its life-history is not yet known.
- a fungal disease of plums and cherries caused by Dibotryon morbosum, characterized by rough black knotlike swellings on the twigs and branches