SCN: The Silent Robber

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By Dairyland Seed Agronomy Team

In certain agronomy circles, soybean cyst nematodes are called “the silent robber.” The reason being is they slowly rob yield, and you don’t dramatically notice it. You just see yield slip away. We hear “I just can’t get my beans to yield like they should.” For many agronomists, especially in SCN hot spots, is the first clue as to what is happening.

A preponderance of soybean lines today carry SCN tolerance and specifically PI88788 resistance. This has been a useful trait for years and continues to have utility. However, as with any trait, repeated use can put stress or selection pressure on the native populations of the pest. In a sense, “sorting or selecting those individuals out of millions that may be tolerant.” We are beginning to see this with PI88788 and the ability of SCN to repopulate on soybean roots with this trait.

Iowa State has great data on the reproduction of SCN on soybean roots. (See the graphs below.) Notice the exponential increase in reproduction on PI88788 versus Peking over the past 20 years. Item three shows the yield performance of Peking lines (Dairyland does not market in that area, however, other Corteva other brands are represented) and in the yellow rectangle in the lower right corner you can reference the percent reproduction.

Item #1

Item #2

Item #3

Dairyland Seed has a strong and unique line up of Peking lines to choose from with more in the pipeline. May we suggest DSR-C990E; DSR-0585E; DSR-1150E; DSR-1383E; DSR-1601; DSR-1881E; DSR-2067E; DSR-2188E; DSR-1919E; DSR-1989E; DSR-2444E; DSR-2525E; DSR-2994E; DSR-3421E; or DSR-3499E.

If you are noticing a yield slide year after year in your soybeans and you have used the same SCN resistance for years, it may be time for an SCN soil test. Even if you haven’t, we would strongly suggest doing so. Procedures for taking good SCN soil samples include:

Fall is a suitable time
Collect 8-inch-long soil cores.
Collect 15 to 20 soil cores per sampling area.
Limit the area sampled to 20 acres or so, if possible.
Collect numerous multiple-core samples in large fields
Collect cores from underneath crop row if soybeans were grown this season. For a more detailed description you can reference the following references.
https://scn.plantpath.iastate.edu/diseases/scnsoilsampling.html
https://www.thescncoalition.com/wp-content/uploads/2021/12/Scouting-and-Soil-Testing-for-SCN-Resource.pdf

The next step is to get the samples analyzed at a SCN lab. There are several options in the Dairyland Seed marketing area. This weblink has an extensive list of labs https://www.thescncoalition.com/state-information/soil-testing-labs/.

Once the results arrive back feel free to contact one of your local Dairyland Seed professionals to discuss a seed plan around managing this silent little thief.