ALTERNATIVE HOSTS OF CASSAVA VIRUSES IN KADUNA AND SOKOTO STATES, NIGERIA
Field surveys were conducted in 2015 wet and 2016 dry seasons to determine the occurrence of alternative hosts of cassava viruses in Kaduna and Sokoto States, Nigeria. Eighteen farms from six local Government Areas namely; Lere, Chikun, Kajuru (Kaduna State), Tureta, Shagari and Tambuwal (Sokoto State) were surveyed. Fifty- four weed samples within and around the farms were collected; Eighteen weeds were identified in wet season while 19 weeds were collected and 18 were identified during dry season. Three viruses were tested; African cassava mosaic virus (ACMV), East African cassava mosaic virus (EACMV) were detected using Triple Antibody Sandwich ELISA and Cassava Congo sequivirus using Double Antibody Sandwich ELISA. In Kaduna State, seven samples were positive to ACMV (38.8%) and four samples were positive to ACMV (22.22%) in wet and dry seasons respectively. One sample was positive to EACMV (5.56%) and mixed infection of ACMV + EACMV (5.56%). Cassava Congo sequivirus was negative in all the samples. In Sokoto State, seven weeds were positive to ACMV (38.89%) and three weeds were positive to ACMV (16.69%) in both wet and dry seasons respectively. Weeds that were identified in both wet and dry seasons were Combretum hispidum (L.) and Euphorbia hirta. Euphorbia hirta (L) was found to be an alternative host to ACMV, EACMV and their co-infection. The identification of Euphorbia hirta as new alternative host has widen the knowledge on viral inoculum. This will help to narrow the gap in spread of the disease.