Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/15/2007
Publication Date: N/A
Technical Abstract: Appreciable yield losses from root rot epidemics on wheat caused by Fusarium fungi are frequently observed in Russia. Chemical fungicides are not always effective in controlling fusarial root rots on wheat. Biocontrol agents may provide an alternative or additional method for managing root rots. Laboratory experiments with F. sambucinum strain FS-94 isolated from wheat rhizosphere showed the strain was non-pathogenic on wheat, did not produce the trichothecene mycotoxin diacetoxyscirpenol in submerged culture, and could not grow at human body temperature. FS-94 synthesized high-molecular weight, non-fungitoxic compounds (HMC) which were extracted with 1M KCl buffered with 50mM phosphate, pH 6.0, purified on Sephadex G-50 and dissolved in water. These compounds prevented F. culmorum growth and sporulation on artificially-infected wheat seedlings, reduced pathogen infectivity, and induced plant resistance. To confirm the protective effect of the HMC under field conditions, small-plot trials were conducted in 2006 and 2007. Prior to sowing, wheat seed naturally infected with soilborne pathogens (predominately Fusarium) were soaked in water or various concentrations of HMC for 3 hours or overnight. The treatments with HMC significantly reduced incidence and severity of root rots throughout the growing season. Maximal efficacy against Fusarium spp. was observed when seed were soaked overnight in 200 µg/ml of HMC, resulting in a 56% reduction in disease incidence and a 63% reduction in disease severity at the tillering stage. Seed treatment also protected plants from Helminthosporium and Rhizoctonia root rots and basal stem rot. Yield in plants treated with HMC was 16.7% greater than in non-treated.