Biology and epidemiology of rice viruses.

The 15 known viruses that occur in rice are rice black-streaked dwarf, rice bunchy stunt, rice dwarf, rice gall dwarf, rice giallume, rice grassy stunt, rice hoja blanca, rice necrosis mosaic, rice ragged stunt, rice stripe necrosis, rice stripe, rice transitory yellowing, rice tungro bacilliform, rice tungro spherical, and rice yellow mottle viruses. This paper describes their geographical distribution, relation to vectors, infection cycles, field dispersal, and development, and lists recorded outbreaks of the viruses. Many rice viruses have become serious problems since rice cultivation has been intensified. Double-cropping of rice using improved, photo-insensitive cultivars of short growth duration has significantly influenced the incidence of these viruses.