Definition of stem rust
1 : a rust attacking the stem of a plant; especially : a destructive disease especially of wheat caused by a rust fungus (Puccinia graminis) which produces reddish-brown lesions in the uredospore stage and black lesions in the teliospore stage and has any of several plants of the barberry family as an intermediate host
2 : the fungus causing stem rust
First Known Use of stem rust
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