Blight
Blight is a rapid and complete chlorosis, browning, then death of plant tissues such as leaves, branches, twigs, or floral organs. Accordingly, many diseases that primarily exhibit this symptom are called blights. Several notable examples are:
Chestnut blight
The chestnut blight is a fungal infection affecting the American chestnut tree that had a devastating economic and social impact on communities in the eastern United States. It later spread to other parts of the world including Italy. The fungus is spread by wind-borne ascospores and, over a shorter distance, conidia distributed by rain-splash action. In the first half of the 20th century it killed an estimated 4 billion trees. Infection is local in range, so some isolated American chestnuts survive where there is no other tree within 10 km. There are at least two viral pathogens that weaken the fungus through a mechanism termed "hypovirulence" that helps trees survive.