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ARS Home » Midwest Area » Peoria, Illinois » National Center for Agricultural Utilization Research » Crop Bioprotection Research » Research » Publications at this Location » Publication #337485

Title: Formation of dry gram-negative bacteria biocontrol products and small pilot tests against potato dry rot

item Schisler, David
item Slininger, Patricia - Pat
item OLSEN, N. - University Of Idaho
item Shea Andersh, Maureen
item WOODELL, L. - University Of Idaho

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/20/2017
Publication Date: 2/24/2017
Citation: Schisler, D.A., Slininger, P.J., Olsen, N.L., Shea Andersh, M.A., Woodell, L.K. 2017. Formation of dry gram-negative bacteria biocontrol products and small pilot tests against potato dry rot. Meeting Abstract.

Interpretive Summary:

Technical Abstract: Pseudomonas fluorescens strains S11:P:12, P22:Y:05, and S22:T:04 reduce important potato maladies in storage including dry rot, late blight, pink rot, and sprouting. Experiments were conducted to identify methods for producing a dried, efficacious biological control product from one or more of these strains. Isolates were grown in a liquid medium for 24 h, amended with differing amounts of carbohydrate-based osmoprotectants, and assessed individually for viability after drying using a high-throughput microtiter plate assay. Fructose and trehalose at 20g/L were the most effective at maintaining the viability of the strains. High titer suspensions of washed cells of each strain then were combined with different grades of diatomaceous earth (DE), perlite, fumed silica and clay and dried for 18-22 h in a controlled RH atmosphere. Several DE products were superior in maintaining cell viability. Combining individual strains suspended in osmoprotectant with DE resulted in dried products with up to 10X higher cell survival. In laboratory assays, the majority of dried products containing only P22:Y:05 or S22:T:04 reduced dry rot by more than 50% (P<0.05, FPLSD) but dried products containing only S11:P:12 were less effective. Fresh, three-strain co-cultures of these strains have enhanced efficacy and consistency of biocontrol compared to the individual strains or blends of these strains. Trehalose and fructose enhanced the survival of each component strain of co-cultures at 1 and 7 days after drying (P=0.05). These co-cultured products reduced dry rot by 74% and 25% in laboratory assays, respectively. Cells survived drying better when combined with DE versus perlite (P=0.05). All combinations of carrier, osmoprotectant, and co-cultured cells reduced dry rot by 65-83% when applied to tubers seven days after product drying. In a small pilot-scale test, dry formulations of these co-cultured strains and the fungicide Stadium TM reduced dry rot decay by approximately 20% and 55%, respectively (P=0.05).