Blight
mid 16th century (denoting inflammation of the skin): of unknown origin.
wiktionary
Uncertain, however given that it was used at one point to refer to inflammation of the skin [1], quite possibly from Middle English *bleighte, *bleȝte, from Old English blǣcþa(“leprosy”) (related to Old English blǣċo(“paleness, leprosy”) and blǣċe(“an itching skin-disease”)); or from Old Norse blikna(“to grow pallid”). [2] Related to bleak.
etymonline
blight (n.)
1610s, origin obscure; according to OED it emerged into literary speech from the talk of gardeners and farmers. It is perhaps from Old English blæce, blæcðu, a scrofulous skin condition and/or from Old Norse blikna "become pale" (from the group including bleach, bleak, etc.). Used in a general way of agricultural diseases, sometimes with suggestion of "invisible baleful influence;" hence figurative sense of "anything which withers hopes or prospects or checks prosperity" (1660s). Compare slang blighter. Urban blight "condition of disrepair and poverty in a previously thriving part of a city" attested by 1935.
blight (v.)
"afflict with blight, cause to wither or decay," 1660s (implied in blighted), from blight (n.). Figurative sense of "exert a baleful influence on" is by 1712. Related: Blighted; blighting.
