Liquid smoke is reported to be effective to inhibit some bacteria. The study aimed to evaluate the effects of liquid smoke (LS) from coconut shell (CS-LS), pinecone (P-LS), and oil palm branch (OPB-LS) on the incidences of blood disease, induced resistance to Ralstonia syzygii subsp. celebesensis, and plant growth. Two days after banana seedlings were treated with LS, ethylene, auxin, lignin, activities of the enzymes of peroxidase (POD) and phenylalanine ammonia lyase (PAL) on the root of the banana seedlings were measured. Then, the seedlings were inoculated by R. syzygii subsp. celebesensis. The plant growth and incidence of blood diseases were observed daily and the 31 st day after the application of LS and this bacteria inoculation. The results showed that the CS-LS, P-LS, and OPB-LS at all tested concentration could suppress the incidence of blood diseases up to 100 %, induce resistance of banana seedlings to the R. syzygii subsp. celebesensis with increased levels of ethylene, auxin, lignin, activities of POD and PAL, and plant growth, significantly. Based on the effectiveness of this bacterial control and the ability to promote the growth of banana seedlings test, it is recommended that the most effective treatment is P-LS 0.5 %.

In Vitro Test of Liquid Smoke against Ralstonia syzygii subsp. Celebesensis, the Cause of Blood Disease in Bananas Blood disease, caused by Ralstonia syzygii subsp. celebesensis, is an important disease of banana plants in Indonesia. Several control methods have been done, but the result were not effective.  Liquid smoke from wood waste is reported to be antimicrobial, but its use for controlling R. syzygii subsp. celebesensis has never been reported. Research was conducted to examine the ability of liquid smoke produced from coconut shell (CS-LS), pinecone (P-LS), and oil palm branch (OPB-LS) in inhibiting the growth of R. syzygii subsp. celebensensis in vitro and its effect on bacterial cell morphology. Efficacy test of liquid smoke was carried out by agar diffusion method and measurement of bacterial density by spectrophotometry with ʎ 600 nm. Observation of bacterial cell morphology was carried out by electron microscopy. The CS-LS, P-LS, and OPB-LS starting from 0.5% concentration showed inhibitory activity against R. syzygii subsp. celebesensis both on triphenyl tetrazolium chloride medium and luria bertani broth. Liquid smoke also caused damage to cell walls and cell membranes. Therefore, liquid smoke has the potential to be used as component in control method for R. syzygii subsp. celebesensis.