Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: August 19, 2010
Publication Date: February 1, 2011
Citation: Slininger, P.J., Schisler, D.A., Olsen, N.L. 2011. Multi-strain co-cultures surpass blends for broad spectrum biological control of maladies of potatoes in storage [abstract]. Potato Association of America. 88:64. Technical Abstract: Pseudomonas fluorescens strains S11:P:12, P22:Y:05, and S22:T:04 have been documented to suppress four important problems in potato storages — dry rot, late blight, pink rot, and sprouting. This research investigates the efficacy and consistency of strain mixtures produced by co-culturing strains together in one vessel or by blending them after separate cultivations in pure cultures. Pure and co-cultures were produced in fermentors, viable cell populations were assessed using a nutrient-based selective plating method to identify and enumerate strains, and the efficacy of treatments was determined with respect to sprout inhibition or severity of Fusarium dry rot, pink rot, or late blight on inoculated tubers. During a 3-year study, both biocontrol efficacy and consistency were assessed in 16 laboratory and small pilot trials. The 3-strain co-culture had a lower mean disease rating than the blend in 9 of 16 experiments examining control of the 3 diseases and sprouting. The co-culture led other treatments in incidences of significant malady reduction relative to the control as follows: 14 of 16 attempts for co-culture, 11 of 16 attempts for blend, 10 of 13 attempts for pure S11:P:12, 8 of 13 attempts for pure S22:T:04, and 9 of 13 attempts for pure P22:Y:05. Using relative performance indices to rank treatment performance across all experiments, the co-culture treatment ranked significantly higher than the blend. A synergy analysis suggested that co-culturing strains stimulated inter-strain activities to boost biocontrol efficacy and consistency, a feature not developed in strains grown separately and mixed just prior to addition to potatoes.