Evaluation of induced systemic resistance agent, Bacillus subtilis strain BAC02-4 against Magnaporthe grisea in rice in field

Bacillus subtilis strain BAC02-4 was tested for its ability induced systemic resistance(ISR) in rice against Magnaporthe grisea We extend these studies to investigate the biological induction of systemic resistance in rice following treatment with the inducer isolate BAC02-4 and naturally infested with Pyricularia oryzae. We also determine levels of ISR activity during the period between disease development and the onset of systemic resistance. Comparition of lesion number according to applied concentration of BAC02-4 to 'Nagdongbyeo' when naturally infested with the conidia of P. grisea. Results from the blast nusery trial using the 'Nagdongbyeo' showed very low rice blast severity with the inducer concentration of 10$\^$8/ cfu level. Considering the low level of treatment and untreated control were observed to have developed typical susceptible lesion type. Highest protection against the rice blast pathogen when applied three times with 5 days interval as root drench at 5 to 6 leaf stage before pathogen challenge. But higher dose of bacterial inducer produced a little stunted plants with less number lesions and delayed disease development. Diseased leaf area of treated with suspension of the isolate which gave about 80％ of control efficacy at 20 days later comparable to that in noninfested, inducer-free soil.