Test For The Soybean Cyst Nematode Before Planting Soybean This Spring

May 05, 2016

By Emmanuel Byamukama

Sampling soil to test for the soybean cyst nematode (SCN) is an important spring activity. Testing for SCN can help determine the occurrence of SCN in your field. For fields where SCN has been detected before, periodic testing can better inform farmers whether the SCN population density is increasing (management program is not working) or if the population density is decreasing (management program is working).

Spring Soil Testing

Soybean cyst nematode can cause up to 30% yield loss without causing obvious above ground symptoms. Sometimes SCN symptoms can be confused with those caused by other stress factors such as nutrient deficiencies or iron chlorosis. The most reliable method for determining the presence of SCN in the soil is through a soil test. Soil testing for SCN is free of charge to South Dakota producers, courtesy of the South Dakota Soybean Research and Promotion Council. Taking advantage of this service will help get a better picture of the current SCN status of a field before planting soybeans this season.

Figure 1. Sampling for SCN can be done anytime provided the soil is not too wet and a soil probe can be pushed into the ground.

Sampling Soil for SCN

To sample soil for SCN, use a soil probe or shovel and obtain 20 soil cores ensuring areas such as field entrances, low yielding areas, and/or along the fence line are included (Figure 2). Larger fields should be divided into 10-20 acre sections.

Figure 2. Sampling for SCN. Use a zig-zag pattern and include field entrance, low yielding areas, and low areas.

Sampling for SCN can be done any time provided the soil is not too wet (can form a paste once rubbed between the fingers) and not frozen so that a spade or soil probe can be inserted to that 0-6” depth. Mix the 20 soil cores well and mail or drop off a minimum of a pint of soil at the SDSU Plant Diagnostic Clinic:

SCN Management

Soybean cyst nematode can be managed primarily through planting SCN-resistant cultivars and through crop rotation. If SCN has been detected in your field, plant soybean cultivars with SCN resistance. Typically SCN-resistant varieties do not cost any more than seed without SCN resistance. If a high SCN population has been found (>10,000 eggs/100cm3 of soil), a longer rotation (>2 years) out of soybean is recommended.

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