Senyu Chen's soybean disease research.

MN Impact: Soybean cyst nematode sampling, education program and disease research improve outlook for Minnesota soybean farmers affected by this pathogen

October 28, 2019

Objective

Minnesota soybean cyst nematode (SCN) sampling and education resulted in increased yields that could be valued as high as $5 million for Minnesota farmers.

Issue

The soybean cyst nematode (SCN) is the most yield-limiting pathogen of soybeans, responsible for annual yield losses of more than 100 million bushels in the North Central U.S. SCN may be present long before producers are aware that fields are at risk because above-ground systems may not be overt. While Extension, agronomists, and other agricultural professionals stress the importance of monitoring and managing SCN, many producers remain unaware of the threat SCN poses, and of how essential monitoring population densities is to maintaining crop productivity.

What has been done

In 2018, with funding from the Minnesota Soybean Research and Promotion Council, Extension developed the Minnesota SCN sampling and education program to increase awareness of the threat of SCN and to encourage SCN sample collection. Presentations reached 861 people with information about SCN and how best to manage it. Free sampling kits were provided at these presentations, including 2,500 sample collection bags. While farmers were responsible for sample collection and shipping, costs associated with sample analysis and education were covered by check-off funds.

Results

A total of 363 samples were submitted for analysis in 2018. Of these, 50.4 percent tested positive for SCN and 44.8 percent of these had egg densities at which yield loss could result even with planting an SCN resistant variety; 6.6 percent had densities so high that planting soybeans is not recommended. After learning this, 47 percent planned to plant a soybean variety with SCN resistance and 29 percent planned to plant a different crop. Participants represented 43,774 acres.

Collaborative research in recent years has resulted in the discovery of SCN resistant soybean lines and potential novel genes (including Rhg1) that are now used in screening new varieties for SCN resistance. Additionally, research has shown that when SCN is present at moderate densities, SCN-resistant varieties can improve soybean yield by up to 40 percent. Using Minnesota's average field size of 160 acres, the value of SCN management after detection could be as high as $29,120 per field. Given that 183 positive samples were identified, the value of the program could be higher than $5 million.