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.
Early blight disease caused by Alternaria solani, Sorr is an important disease in tomato.Biological control is one of the environmentally-friendly control measures of the disease.Vermicompost is a potential source of antagonistic microbes for biological control of plant diseases.The objective of this study were to isolate fungi from vermicompost water extract and examine their abilities to inhibit the growth of A. solani in vitro and suppress the pathogen infection in tomato fruits and leaves.The fungi were isolated from water extract of two types of vermicompost which were cattle manure vermicompost and goat manure vermicompost.The fungal isolates obtained were tested for their antagonistic abilities against A. solani in vitro using adual culture method.The in vitro experiment was arranged in Completely Randomized Design.The selected isolates were examined their abilities in suppressing A. solani infection in tomato fruits and early blight disease in tomato leaves.The in vivo experiments were arranged in Randomized Complete Block Design.The isolation of fungi from the water extract of two types of vermicompost resulted in 14 fungal isolates, which were nine isolates from cattle manure vermicompost and five isolates from goat manure vermicompost.Among 14 fungal isolates, there were seven isolates that inhibited the growth of A. solani in vitro.In tomato fruits, six fungal isolates inhibited A. solani infection by 64%-76% at five days after inoculation.However, two isolates (Trichoderma spp.) colonized the fruit surface after seven days of incubation.In tomato plants, two fungal isolates (Trichoderma spp.) suppressed early blight disease in the leaves by 55.3%-58.2%.This finding showed that some fungal isolates from the water extract of vermicompost were antagonistic to A. solani in vitro and had potential as the biological control agents of early blight disease in tomato.
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