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SCN: Out of sight, out of mind — but they’re still there

John Obermeyer, Purdue University soybean cysts on soybean roots
FIND THE CYSTS: Note the lemon-shaped attachments on these soybean roots. Those are soybean cysts, says Purdue's Jamal Faghihi.
Nematode expert says there is as much need to test for soybean cyst nematodes now as ever.

There was a time when you could count the Indiana counties with soybean cyst nematode issues on one hand, two at most. Today the tables are reversed. You can count the counties where Jamal Faghihi and his staff haven’t found SCN on three fingers: Brown, Monroe and Switzerland. They have documented the presence of SCN in every other county in Indiana.

“There is as much need for an extensive testing program for soybean cyst nematodes today as perhaps ever before,” Faghihi says. The Purdue University Extension nematologist has devoted his career to studying nematodes, spending lots of time learning about their life cycles.

Faghihi explained the current status of SCN testing in this exclusive interview with Indiana Prairie Farmer.

IPF: How have numbers of samples tested at your lab varied over the years?

Faghihi: We reached 5,000 samples per year when the Indiana Soybean Alliance provided free samples for farmers. That program is no longer in effect. Last year we tested just over 500 samples submitted for soybean cyst nematode analysis.

IPF: Does that correlate with a decrease in soybean cyst nematode activity?

Faghihi: No. If anything, it is more important to test for nematodes today than ever before. We know they are in all but three counties in the state. They can cause damage and affect yield without you even knowing they’re there. Yield losses can occur before visible symptoms become noticeable.

IPF: Is it expensive to have routine samples tested for presence of cyst nematodes?

Faghihi: No, that is the frustrating part. It is only $10 per sample. For a $10 investment, you can learn if soybean cyst nematodes are in the field or that part of the field, and at what level.

IPF: When can samples be taken?

Faghihi: Samples for soybean cyst nematode can be taken at any time during the year, no matter what the temperature or current crop. Testing for corn nematodes is more restrictive. They need to be taken four to six weeks after germination, usually around the end of June. You also need to take samples to check for corn nematodes when the temperature is below 85 degrees F. Root samples need to be submitted with soil samples to check for corn nematodes.

IPF: What are the steps to prepare a good test sample for soybean cyst nematode?

Faghihi: We recommend that one sample represents 10 acres. You can use a spoil probe to collect cores at random, just as you would for collecting a soil sample for soil fertility testing. You want to probe 6 to 8 inches deep, collect a number of cores, then mix it and prepare one sample to send to the lab.

IPF: Where do you submit samples?

Faghihi: You can submit samples to the Purdue nematology lab. Find more information here. Each sample should contain a quart of soil, and the bag should be clearly marked for identification purposes. You can expect results in five to 15 days.  If you have questions, email me at [email protected], or call me at 765-494-5901.  

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