While soybean producers may never achieve total elimination of the crop’s biggest yield robber, they have an increasing number of solutions.
Soybean cyst nematodes are responsible for lowering yields in virtually every field. But populations can be dramatically reduced using a mixture of management practices.
Among them is a seed treatment designed to kill the microscopic roundworms before they have an opportunity to damage young roots.
Syngenta scientist Dale Ireland, speaking at the Illinois Soybean Summite, provided tips for keeping the pests at bay.
SCN infestations cause estimated losses of nearly 128 million bushels annually in the U.S. That’s more than the next five soybean-producing countries combined.
“Chances are, if you’ve been growing soybeans for any length of time, you likely have soybean cyst nematode present in your field and growing in numbers,” Ireland said.
“It is far and away the No. 1 pest. We ought to have it very much on our radar screen. The only thing we could do until recently is grow resistant varieties. But there are additional tools you may not be using to help you manage it.”
One is a seed-applied nematicide. Syngenta recently introduced Clariva, a seed treatment comprised of bacteria that parasitize nematodes, eventually killing them. Nematodes themselves are parasitic organisms.
“When you’re feeding on a soybean root, you’re limiting the genetic potential of that root system to grow in its maximum way, to take up as much moisture and nutrients as it possibly can,” Ireland said. “Secondarily, when you have soybean cyst nematode, there are indirect yield effects because you also open that root system up for other diseases to hit.”
Planting resistant varieties is one method of battling SCN. That strategy comes with limitations, however.
One source of resistance is used in more than 90 percent of U.S. soybeans. Other sources of resistance are manifested in seeds that are often not commercially viable, with undesirable qualities such as shattering and low standability.
Rotating beans with non-host plants is another strategy for cutting down on nematode damage. Corn, for example, is not a host plant. On the other hand, some weeds — such as henbit — are.
“You should consider a nematicide package. You need to seriously think about that and look into it,” Ireland said. “I’m not a sales person. As a scientist, some of this stuff is relatively new. It’s not just another cost. I see it as an investment.”
Seed treatments in general offer 25 to 35 days of protection. That grants farmers a head start on controlling plant pests such as nematodes, especially on full-season soybeans.
“Obviously, the earlier you plant, the longer that seed sits in the cooler and wetter soil than you would like, the greater potential return you’ll see on a seed treatment,” Ireland said. “If you’re double-cropping and have great soil moisture, those seeds are going to jump out of the ground more quickly than if you get them planted immediately after your corn.
“I’m not saying that seed treatment doesn’t pay in double-crop beans, but in the scope of things you’d expect that return to be much higher the earlier that seed is planted.”
Early defense against nematodes can pay off big later. Ireland pointed out that nematodes usually begin attacking plants just a few days after the radical — or primary — root first protrudes from the seed.
“When that happens you affect the size of that root system, even weeks later,” Ireland said. “If you can protect that from as many pests as possible, you’ll realize a greater potential for the entire genetic potential that plant has.
“It’s not rocket science. It’s the basis for reaching for reaching the greatest yield potential of a crop.”
Ireland recommends that farmers take soil samples every three to five years to determine whether nematode levels are falling or increasing.
“This is a condition that once you have it you can never get rid of it,” he said. “But you can reduce the numbers by rotating the non-host crops and manage the problem in your crop if you use resistant genetics and a nematicide.”
Source - http://agrinews-pubs.com/
