Selection of streptomycetes isolates for the control of Ralstonia solanacearum in tomato plants

Abstract

The bacterial wilt caused by Ralstonia solanacearum causes high damages in tomato (Lycopersicon esculentum Mill.) culture, mainly under temperature above 25^oC and high relative humidity. Because conventional methods of control have shown low efficiency, biological control is a promising alternative. This work aimed to select isolates of streptomycetes for R. solanacearum control in tomato. Differences were found among the isolates in the in vitro inhibition of the pathogen either in time or pH range. The streptomycetes isolates grew differently in the rhizosphere of seedlings and plantlets of tomato. The isolates SP164, SF232, SAc326 and SG384 showed the highest population densities. In the experiment conducted in soil infested with R. solanacearum, plants treated with the isolate SG384 presented best control level 48 days after sowing, period after which all control plants were dead.