KIMBERLY, Idaho — USDA researchers in Peoria, Ill., partnering with University of Idaho Extension scientists, are finalizing the formulation of a biological control product they’ve developed to control an array of post-harvest potato problems.
The product contains three subspecies of Psuedomonas bacteria, which thrive on nutrients leached from roots. They were discovered in soils from Wisconsin and Illinois potato fields.
UI Extension storage specialist Nora Olsen said only one chemical fungicide is labeled for potatoes in storage, and the biological agent should provide a much-needed new option, which could also be used to treat spuds prior to commercial distribution.
Olsen said Idaho likes the product as a treatment for Fusarium dry rot, which enters spuds through wounds.
“One thing about Fusarium dry rot is it’s universal to growers out there,” Olsen said. “They’re going to have some Fusarium dry rot in their storage.”
The product could also be labeled as a sprout inhibitor and for controlling pink rot and late blight, said David Schisler, a USDA research plant pathologist in Peoria.
“A 50 percent reduction in diseases is something you can count on on a regular basis,” said Schisler, adding the product also shows promise in tank mixes with commercial fungicides.
Schisler and Peoria USDA Agricultural Research Service chemical engineer Patricia Slininger started the project in the mid-1990s, when they selected soil-borne microbial communities that effectively reduced dry rot. They isolated 18 strains from those communities with the best efficacy, narrowing their selections down to three top-performing strains that could be effeciently propagated in a liquid culture at the Peoria lab.
When cultured in the same tank, which minimizes production costs, Schisler has found all three strains offer better control. He hypothesizes the strains are similar enough to coexist, but competition in the tank selects for stronger cells.
In Peoria, where the liquid cultures are propagated, Schisler’s lab has dehydrated the biological control product to differing moisture levels, hoping to reduce transportation costs without sacrificing performance. He’s also testing inert powders to find the best carrier for the product. On Feb. 26, Olsen commenced a three-month storage trial testing 22 treatments, with varying product formulations and scenarios.
“Based upon what we find out this year and the accumulated data over the last several years, we’ll make the decision as to which formulation we’ll move forward with,” Olsen said. “Next year, we’ll scale up to a larger scale. We’re trying to move (the product) through the system and really make it ready for commercial use.”
Olsen said companies have placed an increasing emphasis on biological control agents, which offer a different mode of action than chemicals and don’t lose efficacy when storage conditions are appropriate. One similar biological treatment for potato storage, Bio-Save 10 LP by Jet Harvest Solutions, is already on the market.
Schisler said he’s seeking a company to commercialize his product, which should prove effective over a variety of conditions because it utilizes multiple bacterial strains. Thanks to the volume of research that’s already been done, he believes a company could bring it to market within three years.