By Horacio Lopez-Nicora
Soybean cyst nematode (SCN) is a major soybean pathogen that continues to spread throughout Ohio. Yield reduction commonly occurs with no visible above-ground symptoms. To know if this nematode is present in a field, soil samples must be properly collected and handled. The presence of SCN in a field, but more importantly, the SCN numbers will determine the best management strategy.
When should you sample for SCN? Fall is the best time to sample for SCN. After soybean plants are harvested, a soil test will reveal if SCN is present and at what levels. Knowing your SCN numbers in fall will give enough time to plan for next year and to identify the best management practices([more on SCN management here). Furthermore, if you are planning to collect samples for soil fertility, a subsample can be used for SCN testing. Please see Dr. Lindsey’s article on fall soil fertility sampling.
How should you collect soil samples for SCN? Different sampling strategies can be used to collect soil sample for SCN testing, including those used for soil fertility sampling. We strongly recommend using a 1-inch-diameter cylindrical probe to collect 15 to 20 (more is better) soil cores, 8 inches deep, for every 20 acres. Collect these soil cores in a zig-zag pattern across an area similar in soil texture and cropping history. Thoroughly mix the composite sample by gently breaking the soil cores. At this point we advise splitting the composite sample in two: one for soil fertility and one for SCN testing. Place 1 pint (approx. 2 cups) of soil in a labeled plastic bag and ship it to the lab as soon as possible. For more information on how to collect soil sample for SCN testing visit here.
How should you handle your SCN soil sample? Your soil sample is alive, therefore you must handle it carefully. To keep the nematodes alive, store your SCN samples in a cool, dark place out of direct exposure to sunlight and ship them to the lab as quickly as possible.
Source : osu.edu