A specialist in an area different than cover crops and nematodes returned home from a meeting nearly irate. He had followed a presenter in a program who was filling in for someone and had simply read the script on the PowerPoint slides. Claims were made that cover crops could help with soybean cyst nematode control. This specialist found the claims to be off the wall, and felt it was just more rah-rah speech for cover crops.
That wasn’t the first time someone at a meeting has claimed cover crops could help curb SCN numbers in the field. It seems like a good time to set the record straight, one way or the other.
There is no one better to share facts about soybean cyst nematode activity in Indiana than Jamal Faghihi. The longtime Purdue University researcher and Extension specialist has devoted his career to studying tiny organisms that cause havoc with soybean plants.
Here are key points he separates as fact and fiction.
Fact: Cover crops are not hosts for soybean cysts nematodes. None of the commonly grown cover crops are hosts for SCN, Faghihi says.
Fiction: Data shows that all cover crops can help reduce SCN numbers. There is no evidence to back up this claim, Faghihi says.
Fact: Cereal rye has shown potential for reducing cyst nematode populations. This is the one cover crop that may have potential in working against SCN, he says. “The first year we tested the theory, we didn’t find reductions in nematode numbers following cereal rye,” Faghihi says. “However, rye was planted late, and there was little growth going into winter. The second year we were able to plant earlier, and there was more fall growth. We did see a reduction in soybean cyst populations following cereal rye as the cover crop in that case.”
Fiction: Since cover crops aren’t hosts, the cysts have a hard time surviving. “The truth is that during the time when cover crops are growing in the field, cyst nematodes typically aren’t active anyway,” Faghihi says. Temperatures are cool enough that the nematodes wouldn’t cause issues.
Fact: In greenhouse tests when cover crops are grown in the presence of SCN, there may be an effect upon SCN numbers in some cases that is linked to the cover crop, he notes.
Fiction: Greenhouse results automatically translate to the field. This is where some of the confusion in information that has been passed around about cover crops and the ability to control SCN populations may come from, Faghihi acknowledges. In the greenhouse, SCN is active because temperatures are warmer. In field conditions at the time of year when the cover crop would be growing, SCN is not active because the temperatures are lower. So it’s not correct to extrapolate greenhouse results directly to what you might expect in the field, Faghihi concludes.