Doug Jardine Soybean Diseases

(Doug) I’m Doug Jardine and I’m the Extension Row Crop Specialist at Kansas State University. And today I’ll be talking about soybean diseases. And one of the things I’m going to make a point with the growers is that there can be large swings in the amount of specific diseases from year to year, based on weather. For instance in 2014 there’s a soybean disease called Sudden Death Syndrome. It’s probably the worst we’ve ever seen it in Kansas. One year later in 2015 it was very difficult to find. So, one of the things we’ll do today is talk about what causes some of those differences. A couple of other things that I’m going to be emphasizing is soybean cyst nematode. That remains the number one soybean pest in the entire United States. And on a year-to-year basis, it’s probably if not the first or second most important pest here in Kansas, because of our drier climate in the summer. There’s another soybean disease called charcoal rot that can also be very devastating with regard to yield loss. But today we’re going to give the growers a fair amount on soybean cyst nematode. The varieties that we’re currently using have resistant genes in them. But what we’ve observed in recent years is that resistance is starting to deteriorate and so those aren’t performing the way they did maybe five or ten years ago. And quite honestly many of the growers aren’t aware of that. So, we’re going to try and bring them up to speed on that. One of the other things we’ll talk about today is foliar disease. There’s been a large push in recent years by the chemical companies to apply foliar fungicides even in the absence of disease. Most University Extension specialists think that’s probably not a good idea for a couple different reasons. One, we’ve not been able to measure the significant yield gains that would pay for that application and two we are worried about fungi developing resistance to the fungicides. And we’ve already seen that happen over in the Mississippi River Valley with a disease called frogeye leaf spot, which is present in Kansas. And so we want to make sure that doesn’t develop. I think with regard to efficiencies that really comes into play with the fungicides. A lot of them are using that as insurance, particularly when prices were higher. So, obviously when prices are lower, that’s probably something that they should be taking a strong look at. But the bottom line is that if there’s disease there, they need to go out and treat. And the economics will be there. The returns will be greater than the cost. But if the disease isn’t there, then they just need to keep the money in their pockets. And then the last topic we’ll talk about today are soybean seedling diseases and seed treatment. In years when we have very wet conditions immediately after planting, they can cause significant yield losses. We have kind of a seven year rolling average that we can gain almost two and half bushels per acre by the use of a seed treatment. And there’s lots of different choices out there so today we’re going to try and sort those things out for the producers. The other thing with efficiencies is getting the seed treatment. I think we’ve demonstrated over the last 20 years in not only research here in Kansas, but across the soybean belt, that seed treatments are a very cost effective measure, keeping in mind that in years when we have delayed planting, like we did in 2015, at some point just because the soils are so much warmer and germination is so much more rapid, that may be place where they could cut costs. We don’t often see big differences in yield responses in June planted soybeans with seed treatment. But with the cost of the high tech seeds some growers still view that as reasonably priced insurance. We don’t necessarily discourage that, but that could be a place where they could look a little bit this year to cut costs.

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