Definition
Blight is sudden, severe, and extensive spotting, discoloration, wilting, or destruction of leaves, flowers, stems, fruits, or entire plants.
Etymology. 1611, origin obscure, apparently emerged into literary speech from the talk of gardeners and farmers, perhaps ult. from O.E. blęce, blęcšu, a scrofulous skin condition and/or from O.N. blikna "become pale." 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" (1852). The verb in this sense is from 1712. Hence slang blighter (1896) "contemptible fellow," but often jocular.
Discussion
Blights are historically and economically among the world's most destructive plant diseases.