Biological Control of Potato Soft Rot Disease (Erwinia carotovora) Using Bacillus subtilis and Pseudomonas fluorescens

Potato (Solanum tuberosum L.) is one of the commodities of potential as a source of carbohydrates and important on Indonesia's economy. One of the constraints of potato production is soft rot disease caused by Erwinia carotovora (syn. Pectobacterium carotovorum) which is needed to be controlled. One alternative control measures are the used of bacteria Bacillus subtilis and Pseudomonas fluorescens for biological control. The purpose of this research is to know the potential of B. subtilis and P. fluorescens in single and in combination to inhibit potato soft rot diseases caused by E. carotovora. The results showed that biological control agents B. subtilis and P. fluorescens in single or in combination both of them (T3 to T17) have potential in inhibiting the growth of pathogenic E. carotovora by showing the clear zone. Biological agents provide nearly the same effect if compared with the bactericide Agrept (T2). Based on the results of the statistical analysis, the treatment 11th and treatment 14th showed a clear zone wider than the Agrept treatment (T2). The treatment 11th contain combination of biological agents B. subtilis (109 cfu/ml) and P. fluorescens (105 cfu/ml), while the treatment 14th contain combination of biological agents B. subtilis (107 cfu/ml) and P. fluorescens (105 cfu/ml).