Rice Yellow Mottle Virus (RYMV) Causal agent: Sobemovirus Geographical distribution Management Strategies . The disease was first reported in • Use of tolerant varieties Western Kenya in 1966 and has such as Basmati 370 and subsequently been reported in all rice 217, ITA 310. growing regions in East Africa. • Proper weed management to ensure Fig 1. Structure of Sobemovirus Crop damage and associated that there are no Source: International Committee on losses alternate hosts of the Taxonomy of Viruses, 2011 . Crop loss ranging 10-100% have virus. (Refer to weed been reported depending on plant management factsheet). Favorable conditions for disease age and level of disease resistance Fig 2. Yellow-green colouration • Disinfect hand tools on rice leaves infected by yellow development in the host plant. The highest yield used in rice cultivation • The host range for the virus includes losses occur when plants are mottle virus. using bleach (sodium Asian rice (Oryza sativa), African rice infected early in the growing season. Photo: Nyongesa, KALRO Kibos (Oryza glaberrima), wild Oryza, grasses • The disease symptoms are hypochlorite). including those in the genera Eleusine, observed 1 to 2 weeks after • Ensure that the vector Eragrostis, Echinochloa and Cyperus infection. (beetles) are controlled species. • The disease initially starts as small using appropriate • The disease is spread by several species yellow-green lesions on the leaves methods (Refer to pest of beetles (Coleopteran). The virus is which later form yellow streaks or management factsheet). picked when the insects feed on mottling giving the plant a yellow • Ensure proper diseased plant and is transferred to orange appearance. The infected agronomic practices are

Factsheets for Rice Production, East Production, Rice Factsheetsfor Africa healthy plants as insects fed. plants are stunted and often have Fig 3. Scatted yellow patches in a maintained (Refer to spirally twisted leaves. • The virus is also spread mechanically yellow mottle virus infected field. agronomy factsheet) by contaminated farm tools during • When plants are infected early in the Photo: Nyongesa, KALRO Kibos harvesting. The virus may also spread growing season they may die or fail through contaminated hands or close produce to produce grains. contact between plants.

Contact experts: Mutiga, S, ([email protected]), Mwongera, D; Kirigua, V; Otipa, M; Kimani, J; V. Mugambi, C; Ngari, B; Ochieng, V; Wasike, V; Wandera, F, Wasilwa, L; Too, A; Nyongesa. O. (IRRI); Zhou, B (IRRI)); Mitchell, T. (OSU); Wang, G. L (OSU); Were, V. (TSL); Ouedraogo, I. (INERA); Rotich, F. (UoEm); Correll, J. C. (UARK) and Talbot, N. J. (TSL). E-Guide for Rice Production in East Africa (2019)