Submitted to: Society of Industrial Microbiology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: August 15, 2002
Publication Date: N/A
Technical Abstract: Recent introduction of US-8 genotypes of P. infestans has coincided with an increase in severity and aggressiveness of potato late blight in Canada and the United States. Interest in developing biological versus chemical disease control methods has increased due to recent environmental and health concerns. Eighteen bacterial strains effective in biological control of Fusarium dry rot were screened for their ability to suppress late blight caused by P. infestans strain 693-3 (US-8, mating type A2). Biological control strains were grown in flasks on media varying in nutritional richness. Following cultivation, washed or unwashed stationary phase bacteria were mixed with fungal zoospores to obtain formulations containing ~10(8) CFU/mL (0.5 optical absorbance at 620 nm) and 2 x 10(4) zoospores/mL. Formulations were applied to potato wounds and evaluated for disease suppressiveness after storage of treated tubers for one week in the dark at 15 C and 90% relative humidity. The type of cultivation media used had significant impact on disease suppression when bacteria were washed but not when unwashed. Relative to controls inoculated with only spores of P. infestans, several of the biological control formulations significantly reduced disease by 25% to 60% (P 0.05).