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:
Hypovirus
Hypovirus CHV1 is the only hypovirus found in Europe up to 2000. It is known for reducing the virulence of the fungus that causes chestnut blight (i.e. hypovirulence). "Cryphonectria parasitica", the ascomycete fungus, originated in Asia and causes the disease chestnut blight in several chestnut species ("Castanea" sp.). Although symptoms are mild in Asian chestnut species that have co-evolved with the fungus, they are very severe in the North American chestnut species "C. dentata" and also in the European sweet chestnut, "C. sativa". Hypovirus has been used for protection against chestnut blight in Europe since the 1970s.