Bacteriophages as Biocontrol of Blood Disease of Banana (Ralstonia syzygii subsp. celebesensis)
Bananas are the leading export fruit commodity in North Sumatra, Indonesia. However, banana blood disease, caused by the bacterium Ralstonia syzygii subsp. celebesensis (Rsc), has been the inhibiting factors for the production. The current control methods such as sanitation, use of resistant cultivars, have not yet provided effective results to suppress the spread of this disease. Therefore, this study was aimed to examine the potential of bacteriophages as a biological agent in controlling Rsc in several banana cultivars, carried out at the Plant Disease Laboratory and Screen House, Faculty of Agriculture, Universitas Sumatera Utara, Indonesia. Four types of bacteriophages (ɸBTF1, 2, 3, and 4) were applied on four banana cultivars (Barangan, Cavendish, Raja Bulu, and Kepok Putih). The results revealed that all bacteriophage isolates could reduce the disease incidence and disease severity of the banana blood disease. The quickest incubation period appeared in the treatment of ɸBTF2 + Cavendish and ɸBTF3 + Barangan (2.3 days). Area under disease progress curve (AUDPC) values of mild intensity (3.3) were found in the treatment of ɸBTF1 + Barangan, ɸBTF2 + Barangan, ɸBTF4 + Barangan, ɸBTF1 + Cavendish, ɸBTF2 + Cavendish, and ɸBTF1 + Kepok Putih, while the medium intensity (6.6) was found in the treatment of ɸBTF4 + Cavendish and the highest intensity value (183.3) was found in the control treatment (Kepok Putih and Cavendish). The treatment of ɸBTF3 + Cavendish had the highest dry weight (44.1 g), and the control treatment (Barangan) had the lowest dry weight (11.5 g).