|Slininger, Patricia - Pat|
|OLSEN, N - University Of Idaho|
|Shea Andersh, Maureen|
|WOODELL, L - University Of Idaho|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/31/2016
Publication Date: 8/4/2016
Citation: Schisler, D.A., Slininger, P.J., Olsen, N.L., Shea Andersh, M.A., Woodell, L.K. 2016. Development of dry gram-negative bacteria biocontrol products and small pilot tests against dry rot. Meeting Abstract. ..
Technical Abstract: Pseudomonas fluorescens strains S11:P:12, P22:Y:05, and S22:T:04 suppress four important storage potato maladies; dry rot, late blight, pink rot, and sprouting. Studies were designed to identify methods for producing a dried, efficacious biological control product. The strains were evaluated individually in a high-throughput microtiter plate assay for viability after drying in differing amounts of carbohydrate-based osmoprotectants applied after 24 h of cell growth in a liquid medium. Fructose and trehalose at 20g/L were the most effective at maintaining the viability of the strains. Different grades of diatomaceous earth (DE), perlite, fumed silica and clay were then combined with high titer suspensions of washed cells of each strain. After being 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. Most dried products containing only P22:Y:05 or S22:T:04 reduced dry rot by more than 50% in laboratory assays (P<0.05, FPLSD) but dried products containing only S11:P:12 were less effective. In previous research, these strains had enhanced efficacy and consistency of biocontrol when grown as three-strain co-cultures. Trehalose and fructose enhanced the survival of each component strain of co-cultures at 1 and 7 days after drying (P=0.05) and the 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 treatment combinations of carrier and osmoprotectant with 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).