CLIMATIC EFFECTS ON TRANSBOUNDARY DISEASES IN CITRICULTURE

Incidence of some citrus diseases has been obviously affected by climate change in Japan. Tropical and subtropical diseases that had been rarely seen are now commonly found in the southern part of Japan. Among others, prevalence of citrus greening is mostly feared. The disease is apparently introduced from neighboring countries to Japan, and it occurs in most of the subtropical islands. Warmer climates promote expansion of areas where the vector insect, Diaophorina citri inhabits. Some coastal locations of Kyushu, one of the main islands of Japan, are now infested with D. citri, and outbreak of greening in Kyushu is greatly feared. Citrus phytoplasma disease is another possible transboundary disease under warmer climate, but extensive survey in subtropical islands in Japan failed to detect the disease so far.