Control of Ginseng Damping-Off Disease Using Chitinolytic Bacterial Mixtures

키틴분해미생물을 이용한 인삼 잘록병 방제

Abstract

An effective bioformulation of mixtures of chitin-degrading bacteria has been used successfully to control plant diseases and nematodes. In this study, the bioformulation approach was assessed to control damping-off disease of ginseng. In pot experiments with soils infested with dapming-off pathogens of ginseng, root-drenchings of Chrobacterium sp. C-61, Lysobacterium enzymogenes C-3, and mixture of two bacterial strains grown in chitin minimal medium were signficantly increased emergence of seeds and reduced damping-off disease incidence of seedlings. Efficacy of the bioformulated product depended on the dose and timing of application. In two-year-old ginseng field, the high control efficacies were achieved by soil drenching of two times with an undiluted product or three times with a 10-fold diluted product. In a To-jik nursery (self soil nursery), biocontrol efficacy of the undiluted product against damping-off disease were similar to that of a seed dressing with fungicide, Tolclofos-methyl WP. These results suggest that the bioformulated product containing Chromobacterium sp. C-61 and L. enzymogenes C-3 could be an effective approach to control of ginseng damping-off disease.

본 연구팀에서 개발한 키틴분해미생물 대량배양 bioformulated product는 다양한 작물의 병과 선충의 생물적 방제에 성공적으로 이용되어 왔다. 이 연구에서는 개발된 키틴분해미생물 대량배양 기술을 활용하여 인삼 모잘록병의 생물적 방제법을 확립하고자 수행하였다. 인삼 잘록병 오염 토양을 이용한 포트에서 키틴최소배지에서 배양한 키틴분해미생물 Chrobacterium sp.와 L. enzymogenes 혼합배양액 처리구에는 인삼의 출아율과 인삼 잘록병율이 통계적으로 유의하게 감소하였다. 개발된 키틴분해미생물 배양액의 생물적 방제 능력은 희석여부와 처리시기에 따라 차이를 보였다. 인삼 포장에서 혼합배양액을 파종 전 종자침지하고 출아기에는 토양관주하였을 때, 본포의 2년생 인삼에서 배양원액은 2회 토양관주, 10배 희석액은 3회 토양관주에서 높은 방제효과를 나타냈다. 토직 본포의 경우 배양 원액의 종자 침지에 의한 방제효과는 낮았지만, 종자침지 후 1회 또는 2회 토양관주는 살균제인 톨클로로포스메틸수화제의 종자분의소독과 비슷한 수준의 방제효과를 보였다. 이러한 결과는 Chromobacterium sp. C-61와 L. enzymogenes C-3의 혼합배양액을 이용하여 인삼 잘록병 방제에 화학적 살균제를 대신할 수 있을 효과적인 대안이 될 수 있을 것이다.

Fig. 1. Biocontrol efficacies of the selected chitinolytic bacteria against ginseng damping-off pathogens. (A) In vitro inhibitory activity of the chitin-degrading bacteria (Serratia plymuthica C-1, Chromobacterium sp. C-61; Ly, Lysobacter enzymogenes C-3) on PDA against damping-off pathogens of ginseng: Rh, Rhizoctonia solani; Py, Pythium ultimum. (B) In pot biocontrol efficacies of the selected chitin degrading bacterial cultures grown in a chitin mimimal medium. Ginseng seedlings with damping-off disease infested soils in plastic pots were treated with bacterial cultures or sterile chitin minimal medium as control.

Table 1. Effect of chitinolytic bacterial cultures on emergence of seeds and damping-off incidence of seedlings in pots with natural infested soil

Table 2. Effects of chitinolytic bacterial cultures on emergence of seeds and damping-off incidence of seedlings in pots with patho-gen-infected soils

Table 3. Control efficacy of a combined culture of Chromobacterium sp. C-61 and Lysobacter enzymogenes C-3 on damping-off disease in two-year-old gingseng filed

Table 4. Control efficacy of a combined culture of Chromobacterium sp. C-61 and Lysobacter enzymogenes C-3, and a fungicide on damping-off disease in ginseng nursery