Performance of SCN-resistant soybean varieties in Iowa in 2016

December 24, 2016
ICM News

Soybean varieties that are resistant to the soybean cyst nematode (SCN) are essential tools for managing the pest. Resistance to SCN requires multiple genes, and soybean varieties bred to be resistant may not contain all of the resistance genes necessary to provide maximum nematode control. Consequently, SCN control can vary greatly among resistant soybean varieties, just as yield.

Iowa State University evaluates the SCN control and yield of SCN-resistant soybean varieties in field experiments conducted throughout Iowa annually. The effort is supported, in part, by soybean checkoff funds from the Iowa Soybean Association.

2016 results now available online, coming in print

Soil sample processing and overall data analysis for the experiments in 2016 were completed in mid-December. More than 150 glyphosate-resistant, SCN-resistant and 24 Liberty Link®, SCN-resistant varieties were included in experiments across northern, central, and southern Iowa. Several SCN-susceptible soybean varieties also were included in the experiments for comparison. Four of the SCN-resistant varieties had the Peking source of resistance; all other resistant varieties had the common, PI 88788 source of resistance.

A report of the 2016 results is available online at The report also is available for free download at the ISU Extension Store, Evaluation of Soybean Varieties Resistant to Soybean Cyst Nematode in Iowa-2016, IPM 52. Hard copies of the report will be mailed as a special insert in the Iowa Farmer Today and the Illinois Farmer Today magazines on January 14, 2017.

New format for 2016 report

To make the information more easily viewed and used, presentation of the results was streamlined for 2016. The SCN-resistant varieties are shown in descending order of yield and yield is depicted with bars on the right side of the page, as shown in Figure 1 with results from the experiment in east central Iowa with glyphosate-resistant varieties. To the left of yield data are mean end-of-season SCN numbers (population densities) and blue bars showing the SCN reproductive factor (RF) for each variety. The RF value is the change in SCN soil numbers from planting to harvest. End-of-season SCN numbers and RF values illustrate the amount of SCN control provided by the varieties. Data on the susceptible varieties in the experiment are shown at the bottom of the page.

Figure 1. Results of experiment conducted in east central Iowa with glyphosate-resistant, SCN-resistant soybean varieties in 2016.

Greater yields and lower SCN numbers with resistant varieties

Soybean yields were greater in the 2016 experiments than in 2015 (described here), and SCN population densities were variable among the experimental locations. Overall mean yields of the resistant varieties were greater than the susceptible varieties in all but one of the experiments, in which the mean yields were the same (Figure 2). Yields of individual resistant varieties varied by 10 to 35 bushels per acre in individual experiments. End-of-season SCN numbers were lower for SCN-resistant soybean varieties than susceptible varieties at all locations (Figure 3), and the numbers varied among resistant varieties as well.

Figure 2. Mean yields of all glyphosate-resistant, SCN-resistant soybean varieties compared to susceptible soybean varieties at the field experiments conducted in 2016.


Figure 3. Mean end-of-season or final SCN egg population densities for all glyphosate-resistant, SCN-resistant soybean varieties compared to susceptible soybean varieties at the field experiments conducted in 2016.

More information about SCN

These data are from a limited number of locations and should be used only as a beginning point for developing a SCN management program for any specific field. Performance of individual SCN-resistant soybean varieties in SCN-infested fields will vary among locations and years. Farmers are encouraged to seek out and consider other sources of yield and SCN control data for SCN-resistant soybean varieties and, if possible, to evaluate several SCN-resistant varieties at their own locations to determine the best varieties for their local conditions.

More information about the biology and management of SCN is available at and Iowa State University’s management recommendations for SCN are available online in a downloadable format, Soybean Cyst Nematode (SCN) Management Recommendations, IPM 63.




Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Integrated Crop Management News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on December 24, 2016. The information contained within may not be the most current and accurate depending on when it is accessed.


Greg Tylka Morrill Professor

Dr. Greg Tylka is a Morrill Professor in the Department of Plant Pathology and Microbiology at Iowa State University with extension and research responsibilities for management of plant-parasitic nematodes. The focus of Dr. Tylka's research program at Iowa State University is primarily the soybea...