Growers, researchers report mixed results with soil fungicide

01/01/2012 02:00:00 AM
Tom Burfield

The product did serve as a good tool to fight white rot and rhizoctonia disease in potatoes last season, Gasser says. He plans to try it again with onions next year, perhaps applying it at a higher rate.

“I’m not willing to give up,” he says.

Post-harvest tests

Willie Kirk, a plant pathologist at Michigan State University, has conducted trials with Serenade Soil in post-harvest potatoes. Kirk inoculated tubers with four pathogens: late blight, pink rot, dry rot and pythium leak.

While the untreated check had a 22 percent incidence of late blight disease, the crop treated with Serenade Soil had only a 2 percent to 5 percent disease incidence.

When tubers were inoculated with pythium leak, the untreated check had 40 percent incidence. Of the diseased potatoes, the fungicide Phostrol provided 17 percent suppression and Serenade 20 percent.

With a fairly light incidence of pink rot, Serenade Soil offered about the same control as Phostrol.

In a test involving dry rot, 56 percent of untreated potatoes had the disease while 50 percent of the Serenade Soil-treated were infected. That compared with about 10 percent infection when the tubers were treated with other conventional products.

AgraQuest’s Manker says tests involving inoculated potatoes can be misleading, since extremely high, artificially induced disease pressure can be difficult for any biological fungicide to overcome.

Growers typically contend with low to moderate disease pressure, she says.

“In that situation, the product works really well,” she says. “It’s been a very successful product for us.”

Kirk’s recommendation for growers: Try Serenade Soil on some acreage to see if it works for you.

Testing white mold

At the University of Wisconsin, plant pathologist Amanda Gevens tested Serenade Soil to see how it affected white mold on snap beans.

Last year, Serenade Soil “showed some promise numerically,” but there was no significant difference in controlling white mold.

Gevens hoped to try the test again this year, but conditions weren’t favorable for white mold.

“The story in snap bean white mold is that there’s some promise, and we’d like to further evaluate the use of Serenade Soil as a soil-incorporated treatment,” she says.

She saw conflicting results in tests involving potatoes.

Last year, “We did have significantly better common scab control with Serenade Soil than we had in the untreated control and when compared to a few of the other conventional treatments,” she says.

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