Soybean School: Rotating resistant varieties key to controlling SCN

Soybean cyst nematodes have been stealing yield in Ontario fields for more than 20 years. SCN-resistant varieties are a key tool to help defend against the invading pest, but growers need to ensure they’re not putting the effectiveness of these resistant varieties at risk.

In this episode of RealAgriculture Soybean School, OMAFRA plant pathologist Albert Tenuta says seed companies rely on two main sources of SCN resistance. PI88788 is the the predominant source while Peking resistance is used in a small percentage of varieties.

Tenuta explains that resistant varieties do a good job of managing the pest, but cyst nematodes can still reproduce on the resistant varieties and field populations can build up over time.

To help protect the resistance sources and limit population build-up, Tenuta says there are a number of management rules growers should follow. First on the list is crop rotation: incorporate corn and wheat in the rotation. Nematodes can’t reproduce on these non-host crops.

Tenuta also reinforces the need to rotate resistance sources. As noted, the majority of commercial varieties carry PI88788 resistance, but growers should incorporate Peking resistance whenever possible. “Never use the same soybean cyst resistant variety back-to-back because those populations that are reproducing will produce again at higher levels the next time.”

In the video, Tenuta discusses the need to be careful when using cover crops, especially legumes and the importance new seed treatment products, strong weed control and maintaining good soil health.

Tenuta also advises growers to get out with their shovels, dig up roots and test their soils for SCN every time soybeans come through the rotation. This will determine whether populations are increasing or decreasing and help identify management needs.

Related: Putting the pinch on cyst nematode

Click here for more Soybean School episodes



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