Status of Bacterial Wilt Disease in Major Potato Growing Areas in West Shewa and West Arsi Zones, Ethiopia

Abstract

A field survey was carried out in major potato growing areas in West Arsi and West Shewa administrative zones, Ethiopia, to determine the incidence of potato bacterial wilt (BW) caused by Ralstonia solanacearum. Limited information is available on
R. solanacearum causing potato wilt in these areas. Stem and tuber samples with bacterial wilt-like symptoms were collected from 13 locations in 67 fields for serodiagnosis of the pathogen. BW incidences were higher in West Arsi than West Shewa zone based on both visual field disease assessment and serological assays. Relatively, high disease incidences *were observed in Shashamene, Guder, Kofele and Ambo areas, with R. solanacearum wilt incidences of 73%, 69%, 67% and 67% respectively. The least R. solanacearum wilt incidence was recorded at Wonchi and Tikur-Enchini (20 % each). Improved potato cultivars such as Jalene, Gudane, Argane, Tolcha and Key-Ababa were more vulnerable to R. solanacearum compared to locally used potato varieties. Altitudes of the surveyed locations had negative correlations with a BW incidence. The higher occurrence of R. solanacearum is probably due to farmers recycling of infected potato tubers, cropping system, overlapping of potato growing seasons, abundance of the root knot nematodes and infected volunteer potato from previous seasons. The warmer and humid climate in lower altitudes might have also favored higher incidences of R. solanacearum. Overall, more than 54.4 % of the assayed samples were tested positive for R. solanacearum, and 37.7 % symptomatic samples were tested negative, indicating the presence of other agents causing BW-like symptoms. Current crop yield losses due to this disease need to be quantified with independent studies so as to ascertain the magnitude of the problem in these areas.