Occurrence of rice yellow mottle virus in Tanzania

Abstract

Rice yellow mottle, virus (RYMV) which was first recorded in Kenya in 1966,  is now considered one of the most important diseases in tropical Africa. Surveys were conducted in rice growing aeas in Tanzania to determine the incidence severityand distribution of RYMV in the country. The virus was found in all rice  growing areas surveyed. The incidence and severity of RYMV varied depending on the cultivar grown. In another study, one hundred and twenty varieties and introduced rice material were screened for resistance to RYMV. Thirty eight cultivars showed resistance to the disease in the field and of these only sixteen cultivars were highly resistant to RYMV. ReductIon in grain yield in susceptible varieties ranged from 25 to 100%. Some rice test plants which were not inoculated with the virus showed symptoms of RYMV while other symptomatic plants recorded no yield. High yielding and phenotypically acceptable cutivars such as IR 53234-27-1. CT6948-7-4-2, CABACU and IR 47686-15-5-1 can be used as short-term replacement of the existing susceptable varieties in areas severely affected by RYMV.

Keywords: Disease, Oryza sativa, rice yellow mottle virus yield loss

Tanzania J. Agri. Sc. (2000) Vol. 3 No. 2. 87-96