SURVEY OF ETHIOPIAN PEPPER MOTTLE VIRUSES IN THE CENTRAL RIFT VALLEY OF ETHIOPIA AND EVALUATION OF NETTING DURATION AS MANAGEMENT OPTION

Abstract

Ethiopian pepper mottle virus is one of the major constraints of pepper production in the central rift valley region of Ethiopia. The present study was conducted to assess the prevalence of Ethiopian pepper mottle virus in the region and to determine optimum netting duration for efficient protection of pepper from vector infestation and subsequent viral infection. For this purpose, field survey and an experiment was carried out in the central rift valley of Ethiopia. The survey was conducted on 60 pepper fields in three districts i.e. Butajira, Meki and Ziway districts. Data were collected on the incidence of viral disease, plant height and number of pods per plant. In addition, field experiments were carried out at Hawassa and Meki to assess the efficacy of netting duration against aphid vectors and viral diseases. Data were collected on the number of aphid populations, virus incidence, and pepper growth parameters and yield. Visual inspection of the surveyed fields revealed that almost all the pepper fields (99.6%) had viral diseases. Viral disease incidence ranged from 52.8% in Ziway district to 68.6% in Butajira district. Furthermore, significant variations at (p<0.01) were observed between treatments of the field experiments in terms of aphid infestation, virus incidence and pepper yield. Covering of plots with net for up to 60 or more days after transplanting reduced aphids’ populationper plant by a greater margin (61.8%-76.9% in Hawassa; 52.4-67% in Meki) and virus incidence by 48%-60.8% in Hawassa and 38.6%-48.5% in Meki as compared to the control plots. Total and marketable yields were significantly higher in plots protected by net for up to 60 days or more after transplanting while unmarketable yields were low in those plots. Low virus incidence and aphids’ population in plots covered by net up to 60 days after transplanting and longer resulted in increased yields by 44 %-55 % in Hawassa and 38 %-49.5 % in Meki as compared to the control plots. Unmarketable yield was positively correlated (p<0.001) with aphids population and virus incidence while total and marketable yields were negatively correlated with aphids population and virus incidence. The current results suggest the need to apply control measures at early growth stages to effectively protect pepper plants from aphids and associated viruses.