Is this a Minor Pest?
Yes
Minor Pest Title
Rice Yellow Mottle Virus (RYMV) (Sobemovirus)
Minor Pest Description
Rice yellow mottle virus is endemic in Africa, was first reported in Kenya in 1966, but is now known to occur in almost all irrigated rice growing areas in Africa. This disease can cause up to 92% yield loss on "Super", the most popular rice variety in Tanzania.
RYMV causes severe infections mainly in irrigated rice and is transmitted by beetles (Sesselia pusilla, Chaetocnema pulla, Trichispa sericea and Dicladispa viridicyanea) and mechanically. It is not seed transmitted.
Major symptoms of the disease are yellowing of leaves, stunting of affected plants, reduced tillering of the affected plants and sterility of the seed/grain.
Minor Pest What to do.
- Plant resistant varieties. The following cultivars are reported as resistant to RYMV: Oryza sativa japonica sub-species: 'LAC 23', 'Moroberekan', 'IR 47686-1-1' for direct seeded rainfed lowlands, and Oryza sativa indica sub-species: "WITA 9", "WITA 11" and "Gigante" Ttete) for irrigated lowlands (WARDA)
- Avoid and/or minimise mechanical injuries.
- Avoid exposing healthy seedlings and plants to virus contaminated and infected material (water, soil, cattle faeces and plants).
- Control insect vectors (see above under pests Hispid beetles and flea beetle)
- Transplant early before the outbreak of Hispid beetles and Trichispa sericea, with reduction in spacing of plants.
- Destroy crop residues after harvest and ratoons that harbour the virus and insect vectors.
- Synchronise planting. Wide range and non-synchronous planting dates increase the risks of RYMV outbreaks.
- Plant diverse varieties on a single plot.
- Change of site for nurseries.
- Remove infected plants in nurseries and fields.
- Reduce fertiliser application on attacked plots.
- Weed timely. Early and double weeding helps reduce the weed reservoir of the virus and insect vectors.
- Withhold irrigation water between plantings to provide a rice free period and so restrict the build-up of the virus and insect population.
Minor Pest Position
5
Minor Pest Firstcontent
136
Pest Type
viral
Host Plants
Rice
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