noun Plant Pathology.
Origin of black knot
Examples from the Web for black knot
The fungus is also related to the black-knot fungus on the plum, but its life-history is not yet known.
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
Happily, black-knot may be controlled by cutting out the diseased wood.The Cherries of New York|U. P. Hedrick