Managing Bacterial Wilt (Ralstonia solanacearum) of Potato (Solanum tuberosum) Using Indigenous Biological Control Agent
Joyce Aguk1, Nancy Karanja2, Elmar Schulte-Geldermann3, Christian Bruns1
1University of Kassel, Dept. of Organic Farming and Cropping, Germany
The study was aimed at developing effective indigenous biological control agents (BCAs) isolated from Kenyan soils for use in managing bacterial wilt (BW) caused by Ralstonia solanacearum on potato. #300 rhizobacteria were locally isolated from potato rhizosphere and their antagonistic activity tested against BW in vitro. Promising isolates were then screened in the greenhouse using semi-sterilized soil through soil solarisation and inoculated with BW having 107 CFU. Those treatments that were most effective in control of BW were in consortium (mixtures) and included; Bacillus spp. + Azotobacter spp., Pseudomonas spp.+ Bacillus spp. and Pseudomonas spp. + Bacillus spp.+ Azotobacter spp. with area under disease progress curve ranging from 40-28 compared with the control having 2052-2900. A field study to evaluate these best performing BCAs was conducted for two seasons in 2015. During the first season (March to June), three experiments were established at three locations which were, two highly infected farms with soils containing BW of 103 CFU and an artificially inoculated field located at a research quarantine station with different BW inoculum concentration of 103, 105 and 107 CFU. Tolerant (Shangi) and susceptible (Tigoni) potato cultivars were used in this study. The second season experiment was established during the short rains (October –December) and was carried out only at the quarantine station where BW inoculation (106 CFU) was done and only the susceptible potato cultivar was used.
Keywords: Azotobacter, Bacillus, bacterial wilt, biological control agent, potato, Pseudomonas, Rhizobacteria
Contact Address: Joyce Aguk, University of Kassel, Dept. of Organic Farming and Cropping, Witzenhausen, Germany, e-mail: joycagukyahoo.co.uk