Seed Tuber Cycle and Latent Infection for the Spread of Potato Bacterial Wilt Ralstonia solanacearum (Smith) a Threat for Seed Production in Ethiopia

摘要

The study was conducted to estimate yield and quality losses attributed to potato seed tuber cycle and latent infection at Shashemene Ethiopia. Four consecutive seasons (2009B to 2011A) at five 'kebeles' using three improved potato varieties of Jalene, Gudenie and Awash and two local varieties, 'Nech abeba' and 'Agazer' was done using previous harvest seed for the following season. The results indicated that seed tuber cycle significantly (p<0.05) affected the progress of the disease on the local varieties as compared to improved varieties. The incidence of the disease in the field and the incidence of latent infection in tubers was highly significant (p<0.001) between varieties and among progeny tubers produced in different seasons. In the inception of the trial year, in the field, in the first cycle, the local variety had significantly (p<0.05) higher (20.93%) BW incidence than the improved varieties (3.98%), whereas in the 4th cycle the disease incidence increased to 26 and 53%, respectively. Inthe 4th cycle of progeny tubers, the incidence increased by 75 and 50% from the 1st cycle, respectively. Under ware potato production, in the first cycle, the yield loss was 4 and 7% in improved and local varieties whereas, in the 4th cycle, it increased to 21 and 32%, respectively. When potato was produced for seed, in the first cycle, the loss was 5.34 and 20.78% on improved and local varieties but in the 4th cycle it increased to 28.6 and 67.34%, respectively. Therefore, the study revealed that source of seed and year after year seed revolving were found to be the major factor and the main path for the dissemination of BW disease.