Potential of Pseudomonas sp. & Bacillus sp. for Controlling Fusarium oxysporum, A Causal Agent For Rockmelon Fusarium Wilt Disease

Fusarium sp. recognized as among main pathogen to the rockmelon. The disease was renown as Fusarium wilt disease (FWD). As to the FWD, objectives of this study were to obtain the pure culture of Fusarium oxyporum f. sp. melonis (Fom), and to control the Fom via biological control method using effective bacteria. Beside, the study was also screened the plant growth promoting properties of Pseudomonas sp. and Bacillus sp.. Fusarium oxysporum f. sp. melonis Snyder & Hans caused postharvest disease problem affecting melon production and loss almost 100 % due to this destructive disease. Effective bacteria like Bacillus sp. and Pseudomonas sp. has a good potential to suppress growth of pathogen. Based on the phenotypic identification and morphological characterization of fungus isolated was identified as Fusarium oxysporum f. sp. melonis and it was than confirmed with molecular methods with 99% similarity. Environmental factors that give the optimum growth of Fusarium were evaluated. Based on the result, the growth of fungus showed the best on PDA media (2.538 ± 0.095 cm), 30 °C (2.475 ± 0.096 cm), pH 4 (2.700 ± 0.216 cm) and under continuous dark condition (3.433 ± 0.115 cm). The Bacillus sp. (DP - 1) showed the highest antagonistic activity of fungus and bacteria with 70.68 % in dual culture assay and highest inhibition of fungus growth in double layer test with no ability to growth. As production of protease, all 7 bacteria tested showed positive result of by producing clear zone on PDA media except by B43. From several parameter tested, the result showed that Bacillus sp. has more potential as biological control agent to control the Fusarium wilt disease in rockmelon plant compared to Pseudomonas sp.