Soybean cyst nematode (SCN) is a major problem in soybean fields throughout eastern and central Kansas (Figure 1). Severe infestations may result in stunted and yellow plants with reduced nodulation. In these instances, symptoms are easily confused with drought, flooding, herbicide injury, compaction, or nutrient deficiency. In most fields, however, the only symptoms present may be some uneven growth and a gradual production decline over time. It is important to identify the presence of SCN and monitor levels regularly to determine if management strategies, such as variety resistance and crop rotation, have been successful.
Figure 1. As of October 1, 2023, SCN was identified in 62 Kansas counties that produce >85% of Kansas soybeans. Graphic by Timothy Todd and Chandler Day.
Immediately following harvest is the best time to check fields for SCN and start planning for next season. Confirming the presence of SCN, determining population levels, and monitoring the effectiveness of resistant varieties are the basis for a successful integrated management program.
To collect a SCN sample, you will need:
Recommended field pattern for sample collection:
If your field is fairly uniform, divide it into quadrants for your SCN sample collection. Sections of the field that have had different cropping histories or have different soil types should be sampled separately. For each quadrant or area of the field, you will collect 10 to 20 cores to a depth of 6 to 8 inches.
It is important that when collecting soil cores, you walk in a systematic pattern, such as a “Z” pattern (Figure 2). Collect a total of 10 to 20 soil cores, emptying each into the bucket after collection. All core samples should be mixed well to account for minor variation between cores. After mixing, collect 1 pint of soil, approximately 2 cups, in a labeled plastic bag and seal.
Figure 2. Example of a good sampling pattern for collecting soil to test for SCN.
When sending your samples to the diagnostic lab, make sure to:
K-State Plant Disease Diagnostic Lab
4032 Throckmorton PSC
1712 Claflin Road
Manhattan, KS 66506
Internal Clients (KSRE agents) = $25
External Clients (crop consultants, individual producers, etc.) = $35
Remember, your results will only be as good as the sample you send to the lab!
Check out this short, informative video from our lab: Soybean Cyst Nematode-SCN Sampling 2022, https://youtu.be/b6Eo0isI1I0 .
For more information, feel free to contact us at the K-State Plant Pathology Department.
Soil sampling for fertility too?
Save some time in the field if you plan on sampling your fields for soil fertility. The sampling protocol is very similar to the protocol for SCN. All you need to do is split the samples into two sets – one for the Soil Testing Laboratory and one for the Plant Disease Diagnostic Laboratory. Remember to keep the soil for the Plant Disease Lab in the field-moist state and follow all the shipping and handling instructions listed above. More information on soil fertility testing can be found here: https://www.agronomy.k-state.edu/outreach-and-services/soil-testing-lab/
Timothy Todd, Nematologist