Suppression of Bacterial Wilt and Fusarium Wilt by a Burkholderia nodosa Strain Isolated from Kalimantan Soils, Indonesia.

A trial was conducted to suppress bacterial wilt of tomato (BWT) caused by Ralstonia solanacearum using biocontrol agents (BCAs) isolated from soils in Kalimantan, Indonesia. Five isolates were selected from 270 isolates as better performing BCAs through screening four times using a pumice medium. The isolates selected were identified as Burkholderia nodosa, Burkholderia sacchari, Burkholderia pyrrocinia and Burkholderia terricola according to 16S rDNA sequences, fatty acid composition and carbon source utilization patterns. Among them, B. nodosa G5.2.rif1 had significant suppressive effects on Fusarium wilt of tomato (FWT) and spinach (FWS) as well as BWT. When B. nodosa G5.2rif1 was inoculated into a pumice medium in combination with sucrose, it showed even more stable disease suppression for BWT, but not for FWS. This suppression was considered to mainly occur through competition for nutrients. In two times greenhouse experiments for BWT using pots comparable in size to those used commercially, B. nodosa G5.2rif1 significantly suppressed the disease index by 33-79%, with no inhibitory effects on the growth, yield and quality of tomatoes.