ABSTRACT
Field surveys were conducted during the 2016 dry season in three Local Government Areas in Sokoto and Zamfara States of Nigeria to determine the occurrence, distribution and alternative hosts of viruses of tomato [Solanum lycopersicum (L.)]. A total of 18 tomato farms were surveyed in the two States, 9 in each of the States. Sampling was done in five 4Ó4 m2 quadrants in the three selected fields per Local Government Area. Tomato plant with curl, mosaic, mottling, distortion, stunting, chlorosis and necrotic symptoms, as well as, asymptomatic plants were sampled. A total of ninety weed samples,forty five from each of the States were also collected during both dry and rainy seasons.The presence of tomato viruses was detected using the Double antibody sandwich enzyme linked immunosorbent assay (DAS-ELISA) forTomato aspermy virus (TAV) and Tomato mosaic virus (ToMV) and the Triple antibody sandwich- enzyme linked immunosorbent assay (TAS-ELISA)for Tomato leaf curl virus (TYLCV).Tomato aspermy virus, Tomato mosaic virus and Tomato yellow leaf curl virus were detectedeither singly or in mixed infections in all the three Local Government Areas each of Sokoto (TAV 17 %, ToMV 19.3 %, TYLCV 3.7 %, TAV + ToMV 7.4 %, TAV + TYLCV 3.7 %, ToMV + TYLCV 8.9% and TAV + ToMV + TYLCV 2.2 %) and Zamfara (TAV 20 %, ToMV 17.8 %, TYLCV 11.9 %, TAV + ToMV 3.7 %, TAV + TYLCV 12.6 %, ToMV + TYLCV 5.2 % and TAV + ToMV + TYLCV 2.2 %) states respectively. In Sokoto State, one weed species (Ludwigia decurrensWalter.) from the family Onagraceae,was establishedas a host of Tomato aspermy virus (TAV). Twoweed species (Thelepogon elegans L. andPennisetum pedicellata Trin)and one weed species (Vigna ambasensisVigamb.) from the Poaceae and Fabaceaerespectivelywere hosts of Tomato mosaic virus (ToMV). Three weed species (Euphorbia hirta L., Physalis peruviana L. and Eclipta alba L.) from three different families (Euphorbiaceae,Solanaceaeand Asteraceaerespectively) were found to be hosts ofTomato yellow leaf curl virus (TYLCV). In Zamfara State, one weed species (Phyllanthus amarus Schum & Thonn.) from the family Euphorbiaceaeidentified as a host of Tomato aspermy virus (TAV). Two weed species (Pennisetum pedicellata Trin. and Portulaca oleraceaL.) from the families (Poaceae and Portulacaceae, respectively) and one (Euphorbia hirta L.) from the family Euphorbiaceae were identifiedas ahosts ofTomato mosaic virus (ToMV) and Tomato yellow leaf curl virus (TYLCV) respectively.
