Investigations on the mode of transmission of rice yellow mottle virus (RYMV) revealed that it is located in the rice husks. It is therefore, not transmitted through rice seeds. The virus was transmitted through leaf debris, empty rice spikelets, intertwining roots, leaf contact, rice stubble, contaminated hands and from closely spaced plants. Chrysomelid beetles, Chnootriba similis Thurnberg (Coccinelidae) and some long homed grasshoppers transmitted RYMV. The virus is not transmitted by nematodes. Oryza sativa L., O. glaberrima, and O. barthii are systemic hosts while O. longistaminata and a few weed species are local lesion hosts. The virus was readily detected by visual assessment based on the standard evaluation system (SES) and a serological test utilising enzyme linked immunosorbent assay (ELISA) and agar gel diffusion.

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Observations on the biology of Callosobruchus maculatus ( Fab.)

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