Incidence, severity and distribution of yellow leaf curl disease of tomato in Kenya

Abstract

Tomato (Solanum lycopersicum L.) is an important fruiting vegetable grown in Kenya because of its commercial and high nutritional value. Viruses are a major constraint to tomato production in tropics and sub tropics, eliciting symptoms like stunting, leaf mosaic, distortion, chlorosis, mottling, and vein clearing similar to those caused by abiotic factors. Although begomoviruses are known to cause tomato yellow leaf curl disease (TYLCD) in Kenya, there is limited knowledge on the disease status in tomato fields. The objective of this study was to determine the incidence and distribution of TYLCD in Kenya using the double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) technique. A survey was carried out in eight major tomato growing regions (259 fields) in Kenya during September to December, 2018. Presence of tomato yellow leaf curl virus was further confirmed using DAS–ELISA. The disease was present across all the counties surveyed and its prevalence, incidences and severity varied across the counties and among the fields. The mean TYLCD prevalence ranged from 19.5% in Bungoma County, to 64% in Kwale County. There was significant difference (P<0.05) in disease incidences among the varieties sampled and the incidence was lower in plants grown from hybrids seed compared to conventional varieties. Mean disease severity was significant (P<0.05) and ranged from 0.18 to 2.20. Most farmers planted non-hybrid seeds. There is need for further determination of the diversity of begomoviruses infecting tomato using other techniques to provide more information towards breeding TYLCD-resistant tomato varieties.