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Will New Biocontrol Product Intercept Sclerotinia?

Saturday, February 2, 2002
filed under: Disease

Will New Biocontrol Product Intercept Sclerotinia?

Growers, crop scientists looking forward to giving Intercept WG a field workout in 2002

Intercept WG offers promise as a new biological product to control Sclerotinia in sunflower and white mold in canola, dry beans, soybeans, and other vulnerable broadleaf crops. Growers and crop scientists alike are looking forward to experimenting with it in the field, however, before endorsing the product as a viable treatment.

Approved by the Environmental Protection Agency last spring, Intercept WG is labeled for higher-value crops in other parts of the country as Contans WG. It is literally a fungus-fighting fungus. The product’s active ingredient is Coniothyrium minitans, a parasitic fungus that feeds on Sclerotinia sclerotiorum, the organism which causes Sclerotinia/white mold. Once applied and incorporated into the soil, Intercept WG attacks and destroys sclerotia, which are the hard, black bodies that fall to the soil and reproduce the disease.

The product was developed by a biological products manufacturer in Germany, helped along by funding through several European governments to encourage development of ecologically friendly plant-protection agents. The product is deemed safe by EPA, because the Coniothyrium fungus is a normal inhabitant of most agricultural soils.

Encore Technologies is the U.S. product distributor. Company president David Goulet says that although a limited amount of the product was sold last fall, this spring will mark the first full sales campaign. Encore is in the process of establishing a network of dealers and distributors across the Dakotas. The product may eventually be sold in the High Plains, but for now the company is concentrating its efforts where Sclerotinia has been the biggest problem, says Goulet.

Reg Herman, who farms west of Devils Lake, N.D., was skeptical but interested when he first heard about the product. So he traveled to the company’s headquarters in Minnetonka, Minn., to learn more about the product. “As a farmer, when a new product comes out, a part of you always says, ‘I wonder if this is legitimate?’ So I wanted to check out the company and the research behind this product,” Herman says.

He came away impressed, but wanted to try the product to see how the product would work in his “real world” field conditions. Herman agreed to work with the company to try the product on his farm. He applied 1,500 pounds of product on 1,500 acres last fall, on fields with a history of Sclerotinia problems. He’ll plant sunflower on those fields this spring. “I want to test this in what I would consider really severe conditions,” says Herman.

This spring, he’s also going to apply more product and conduct further on-farm experiments: In a tighter sunflower rotation, in fields comparing application rates of 1 and 2 lbs per acre, and to test product efficacy in soybeans, dry beans, and canola as well. “I hope to get a better idea in late July or early August what the fields that were treated last fall will look like,” he says.

In the meantime, Herman has become so convinced in the product’s legitimacy that he is working with Encore to set up its network of dealers and distributors, and to set up on-farm plot trials with farmer cooperators.

Crop Research Trials

Crop scientists are testing Intercept WG too. In the fall of 2000, Joe Krupinsky, plant pathologist at the USDA-ARS Northern Great Plains Research lab in Mandan, N.D., treated soil with the product at a rate of 2 lbs per acre, on plots where a Sclerotinia-susceptible sunflower hybrid was grown. Spring wheat was then planted on these plots last year, and this spring, the Sclerotinia-susceptible sunflower hybrid will be planted on the same plots again. Other plot trials are testing the product on back-to-back sunflower ground, and how the product performs on 1) no-till; 2) incorporated soil treatment that is tilled once; 3) incorporated soil treatment that is tilled twice.

Tom Gulya, plant pathologist with the USDA-ARS Northern Crop Science Lab in Fargo, N.D., is testing the product in plots near Oriska, N.D. In the plots, the product was applied in May, 2000 at rates of 1 and 2 lbs per acre on soil planted to sunflower that had severe head rot infection in 1999. Spring wheat was planted on the plots in 2000, and then to sunflower in 2001. Soil samples are being analyzed Luis DelRio, North Dakota State University plant pathologist. Data should be available by spring.

Gulya says more research is needed on different facets of biocontrol of soil-based sclerotia, including how soon natural biological control takes place following a severe head rot epidemic, as well as how the product performs in situations of low, medium, and high infections. Gulya and DelRio are planning to begin a multi-crop field trial this spring, conducting further product evaluations on canola, dry beans, and sunflower.

Encore’s Goulet points out that along with European data that supports the product’s efficacy in suppressing Sclerotinia/white mold in susceptible field crops, two years of research conducted by Walt Stevenenson at the University of Wisconsin indicates “excellent” control of white mold on snap beans and dry beans with the product.

Goulet says Intercept is making big gains in the snap bean market in Wisconsin, where the product may become standard use with some producers who contract with processors. Goulet foresees that being a possibility with confection sunflower too someday.

Mike Clemens, who farms near Wimbledon, N.D. and serves on the National Sunflower Association’s board of directors, applied 1 lb of Intercept incorporated with Treflan last fall on fields where he’ll plant sunflower and dry beans this spring. On one field, he applied Intercept to one half, and left the other half as an untreated check. “The fields I put it on should have a fair amount of Sclerotinia, because in 1999 the infection on those fields was at least 50%. Since Benlate is no longer available for dry beans, I’m interested to see how this product will help with white mold. This is about half the cost of a fungicide, so we’ll see if it works,” he says.

Herman says Intercept can be safely tankmixed with a number of chemicals, including Treflan and Roundup. Encore is testing whether the product can be applied with liquid nitrogen, or impregnated on DAP 18-46-0 fertilizer.

It is important to note that Sclerotinia spores are produced when conditions are wet for about seven or more days any time from May to September. The spores land on dead plant material of susceptible plants and require a film of water for infection to occur.

It is not known for sure how far the spores can travel, but it is likely they may travel from a neighboring location in the right conditions.

The best test to determine the effectiveness of the Intercept fungus is to plant sunflower into those treated soils to determine the amount of root infection. Sunflower is the only crop that can be infected by root contact of the sclerotia in the soil. If Intercept has done its job in the soil, there should be limited Sclerotinia wilt in the field. – Tracy Sayler

Fast Facts About Intercept WG

? It’s made of spores of the fungus Coniothyrium minitans. Once applied and incorporated into the soil, the organism attacks and destroys sclerotia before the bodies germinate and spread mold-causing spores onto the susceptible crop.

? It’s targeted for use on crops susceptible to Sclerotinia, including dry beans, canola, flax, safflower and sunflower. Application rate is 1-2 lbs per acre in 10 to 20 gallons of water.

? Product cost ranges between $10-$13/acre.

? It is a naturally-occurring fungus that will not harm plants, animals or water quality. It is not genetically-engineered.

? The product can be applied pre-plant or post-harvest, at least 45 days prior to a Sclerotinia disease outbreak, to allow time for the product to attack and kill the sclerotia in the soil before temperature and moisture conditions cause a mold outbreak.

? Product granules should be dissolved in water and applied to the field, incorporated into the top two or three inches of soil. If the depth of incorporation is greater then 3 inches, the application rate should be increased by half the recommended number of pounds.

? The product only controls Sclerotinia/white mold; no other diseases.

? The product is listed by the Organic Materials Review Institute (OMRI) for use in organic production.

? High heat can destroy the product. It should be stored in a dry, cool place out of direct sunlight and kept away from heat sources above 72 degrees F. The product is not harmed by extreme cold temperatures.

? When stored at temperatures below 72 degrees F, an unopened package of Contans WG has a minimum shelf life of six months. Once the product is opened, however, shelf life is greatly reduced. It should be sprayed immediately after the product is mixed with water.

? The product is tank mix compatible with most formulations of trifluralin, as well as other chemical products. The list of compatible tank-mix products as well as further product information can be found online at Click on the “products” link, then “Intercept WG.”

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