^aKeefektifan Formulasi Biopestisida Berbahan Aktif Bakteri Endofit dan Plant Growth Promoting Rhizobacteria Setelah Penyimpanan untuk Mengendalikan Layu Bakteri pada Tomat

Abstract

Ralstonia solanacearum is one of the important pathogens that cause bacterial wilt in tomatoes which is difficult to be controlled because it has a lot of races and able to survive in the soil for a long time. As an alternative, biological control agents such as endophytic bacteria and PGPR have been widely applied to control the bacterial wilt disease. There were some isolates of endophytic bacteria and PGPR have been effective as biological control agents that suppress bacterial wilt disease, such as B. subtilis AB89, P. fluorescens RH4003, and S. epidermidis BC4. This research was conducted to evaluate the effectiveness of biopesticide formulations which contain endophytic bacteria or PGPR B. subtilis AB89, P. fluorescens RH4003, and S. epidermidis BC4 after storage to control the bacterial wilt disease of tomato. Each of the bacteria was formulated using talc powder and liquid medium wich added with xanthan gum (XG) and stored for 3 months at 11-14 ºC. The effectiveness of formulation were examined in the greenhouse. Two weeks old of tomato plants were transplanted into polybags with diameter of 25 cm filled with soil infested by R. solanacearum. The tomato plants were treated with liquid formulation of B. subtilis AB89 (BSC), powder formulation of B. subtilis AB89 (BST), liquid formulation of P. fluorescens RH4003 (PFC), powder formulation of P. fluorescens RH4003 (PFT), liquid formulation of S. epidermidis BC4 (BC4C), powder formulation of S. epidermidis BC4 (BC4T), and sterilized distilled water as control. Ten mililiters of liquid formulation were poured around the root of tomato after transplanting and 10 g of powder formulation was mixed with soil around the root. Plant growth and the disease incidence were calculated every week, up to 6 weeks after transplanting. The experiment was conducted as randomized complete block design with 7 treatments and 3 replication as blocks. The data were analyzed by analysis of variance with DMRT using statistical analysis system (SAS) version 9.1. This research shown that the most effective formulation after storage was liquid formulation of B. subtilis AB89. Liquid formulation of B. subtilis AB89 and P. fluorescens RH4003 shown higher index of disease suppressing compared with powder formulations and control.