nematodes create wounds by which the fungus can infect the plant more easily. “SDS is most visible when the soybean crop enters the reproductive stages of development, because most of the resources of the plant begin to shift from vegetative growth to producing and filling pods,” says Tenuta. “When this shift in resources occurs, the plant’s natural defense mechanisms are reduced, especially under stressed conditions, allowing the disease-causing organism an opportunity to begin the infection process.” SDS is characterized by yellow speckling or spotting between leaf veins, both of which become larger as the disease progresses. In severe cases, the entire area between the veins becomes brown and dry, eventually falling out. Veins are all that remain, having stayed green the entire time. Premature defoliation and death are subsequent characteristics Cutting the root and the stem, says Tenuta, will expose a light brown or gray discolouration of the cortex tissue in the tap root and the stem. This will extend from the roots up through the stem. “Although the leaf symptoms may resemble brown stem rot, in SDS infected plants the pith of the stem remains white whereas brown stem rot infected plants have a brown and disintegrated pith.” RAPID, INEXPENSIVE GENE IDENTIFICATION 2021 was the inaugural year of the SDS resistance project. Thus far, a variety of genes were identified and incorporated into plant populations for indoor testing. These test populations — currently relocated to Costa Rica to avoid the difficulties of growing in the Canadian winter — will be field-tested in Ontario in 2022 to ensure their suitability for local conditions. “If we can do something that reduces the threat eight or more years from now, it’s worth it,” says Eskandari. “We don’t do any variety selection before the fifth generation…The data is great for discriminating tolerant genes, but we need to evaluate the errors while making sure it makes a good yielding, high quality crop.” Alongside introducing SDS resistance genes into new Ontario-adapted food-grade cultivars and germplasm, a second aim involves the development of molecular genetic-based toolkits. Intended for future breeding programs, such toolkits will speed up the process of developing new varieties by giving researchers a starting place — a sort of best-management-practice suite of genetic options — rather than forcing them to begin searching anew. This method will also make the process considerably cheaper. “The development of Ontario-adapted commercial soybean cultivars that are resistant to SDS and SCN will provide Ontario’s soybean growers with new tools to fight against the most yieldlimiting soybean pests in the region, and increase production,” says Eskandari. The project was funded in part by the Ontario Agri-Food Innovation Alliance, a collaboration between the government of Ontario and the University of Guelph. l ONTARIO GRAIN FARMER 19 FEBRUARY 2022 This research project received funding from Grain Farmers of Ontario. As a long-time farmer, Bradley knows stuff happens when he's juggling work sunup to sundown everyday. Good news is, he also understands his insurance coverage thanks to The Commonwell and our local, insurance-savvy brokers. Knowing you're covered and understanding that coverage creates confidence. It's our job to ensure that happens - so no matter what else happens, you come out on the right side every time. Take the surprises out of your farm insurance by visiting thecommonwell.ca/farm to find a Commonwell broker. @#&*! HAPPENS
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