The Abilities of Bacteria and Yeast Isolated from Vermicompost Water Extract to Inhibit Alternaria solani in vitro and Early Blight Disease on Tomato

Abstract

Early blight disease (Alternaria solani Sor) is one of limiting factors in tomato production. Bacteria and yeast are potential for biocontrol of plant diseases.  Sources to obtain biocontrol agens is water extract of organic matters. The objective of this study was to examine the abilities of bacteria and yeast isolated from vermicompost water extract in inhibiting the growth of A. solani in vitro and suppressing the pathogen infection in tomato fruits and leaves. Two types of vermicompost used in this study were cattle manure vermicompost and goat manure vermicompost. The isolation of bacteria and yeast from the vermicompost water extract resulted in 14 isolates, which were 10 isolates from cattle manure vermicompost and four isolates from goat manure vermicompost. Among the isolates, six isolates (three yeast and three bacterial isolates) inhibited the growth of A. solani in vitro by 42.8% – 79.1%. In tomato fruits, five isolates inhibited A. solani infection by 70.6% - 100.0%.  In tomato plants, four isolates suppressed early blight disease in tomato leaves by 56.2% - 83.5%. The isolate that showed consistent effects in vitro as well as in vivo was bacterial isolate KB 3. This isolate was potential as biocontrol agent of tomato diseases caused by A. solani.