potato murrain vs potato disease

potato murrain and potato disease both are nouns.

Word	Noun	Adjective	Verb	Adverb
potato murrain	Yes	No	No	No
potato disease	Yes	No	No	No

As nouns, potato murrain and potato disease are synonyms defined as:

Other synonyms of potato murrain include potato blight, potato mildew, potato mold.

potato murrain (noun)	potato disease (noun)
a blight of potatoes	a blight of potatoes