Any of several plant rusts producing black discoloration, especially the winter or teliospore stage of Puccinia graminis, a serious pathogen of wheat and other cereals.
Origin
Late 18th century.
Definition of black rust in US English:
black rust
noun
Any of several plant rusts producing black discoloration, especially the winter or teliospore stage of Puccinia graminis, a serious pathogen of wheat and other cereals.