melanose
/ˈmɛlənəʊs/noun
A plant disease characterized by blackening of tissue; specifically (a) a disease of grapevines caused by the fungus Septoria ampelina, which causes a blackish-brown leaf spot; (b) a disease of citrus trees caused by the fungus Diaporthe citri, which causes fruit rot, and blackish-brown spots on twigs, leaves, and fruit.
Origin
Early 19th century (in an earlier sense). From French mélanose from mélano- + -ose.