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The NDSU Extension weekly podcast In the Pod: Soybean Updates delivers timely insights and expert advice on soybean production.
You're listening to In The Pod, Soybean Updates, a weekly trek into the latest soybean information from NDSU Extension. It's not exactly news that SCN or soybean cyst nematode can take a big bite out of soybean yields. Let's talk management of SCN with Wade Webster, NDSU Extension Plant Pathologist. Wade, what exactly is soybean cyst nematode or SCN?
Wade Webster:Soybean cyst nematode is actually the number one yield reducing pest that we have of soybeans. What it is is a small microscopic roundworm, lives in the soil. We can't see it with the naked eye very well. The best we can do is see the small lemon drop shaped structures that form on those roots. During the season, they'll look yellow, but as they mature, they'll turn more brown in color, which hardens them up. In this pest, what it does is it attacks those soybean roots and it pulls out all the nutrients, all the water and the juices that are inside those roots that make that soybean healthy, and it feeds that worm. And when that worm gets in there, it'll reproduce and it'll start to form new eggs, which is that next generation. And so this is what's very important about Essiena is understanding that that cycle from cyst to new cyst only takes about three to four weeks. So we can get three to four generations per season in the state of North Dakota.
Bruce Sundeen:How can soybean farmers manage SCN?
Wade Webster:Yeah. So to manage SCN, we do have some very good strategies for us. So the first one, which is season long control, is going to be genetic resistance, and we have some strategies there, including two different sources of resistance called p I eight eight seven eight eight and peaking. Both of these are different, so it's different mechanisms attacking that SEN pest, but they can both be very effective. However, we have been seeing that eight eight seven eight eight is starting to break down across the state, and so it's important that if you're seeing that eight eight seven eight eight varieties not performing as well, it would be useful to rotate with a peaking.
Wade Webster:Now also talking about rotation is other crops, and we have a lot of other crops that are a non host for SCN except for dry beans. So dry beans can successfully allow SCN to reproduce, but if we use corn, small grain, sunflowers, those are all viable options for managing and bringing those SCN numbers down. And then finally, we also have seed treatments, and seed treatments are a great tool for slowing down that first generation of cysts, but it will not provide that season long control. Now in addition to those three, we also have the soil sampling that is critical for being able to identify SCN. And thankfully, we have the SCN soil sampling program that's hosted through NDSU and funded through the Soybean Council here in the state of North Dakota. And what this allows farmers to do is go out into your fields and test free of charge for SCN. And so we distribute these SCN bags across the state to your local county offices. These offices then hold those bags for you, drop in, pick them up, get out and test your fields, and then you'll get those numbers back. And those numbers are important because, one, they'll be able to tell you if SCN are present, but they'll also be able to tell you at what level those cysts are there. And you can determine based off of your management strategies based on those numbers if those management strategies are working or not. And then it'll also help you guide if soybeans should or can be planted back into those fields or not.
Bruce Sundeen:Wade, when is the best time of year to do sampling?
Wade Webster:Yes. The important time for SCN sampling is gonna be during the fall when those numbers are the highest. And so this is why it's very important to talk about it right now. However, we can sample throughout the entire season unless the ground is frozen, so try to get out and get those samples as soon as possible before the ground freezes here in the next couple of weeks. But if we were to test in the spring, those numbers might be slightly lower. However, what's important is doing the sampling at the same time every year. That way, if we can track it, we're catching it at the same time point. But, that fall sampling is where we're gonna have the highest numbers, and it'll be a best snapshot of what that field looks like.
Bruce Sundeen:Thanks, Wade. Our guest has been Wade Webster, NDSU Extension plant pathologist. You're listening to In The Pod, Soybean Updates, a weekly trek into the latest soybean information from NDSU Extension supported by the North Dakota Soybean Council.