Soybean cyst nematode (SCN) remains the number one pest in soybean production in the United States. Per the Crop Protection Network review conducted from the 2023 production year, SCN was responsible for 87 million bushels of yield loss.

Soybean cyst nematode (SCN) remains the number one pest in soybean production in the United States. Per the Crop Protection Network review conducted from the 2023 production year, SCN was responsible for 87 million bushels of yield loss. Today, both public and private researchers and labs have identified SCN in nearly all major soybean growing areas in the U.S. (Marett and Tylka, 2020)

SCN-resistant germplasm sources have been identified, developed, and increasingly incorporated into soybean breeding programs across the industry. These resistance sources are derived from soybean plant introduction (PI) lines with unique resistance gene combinations. Today, most new soybean variety releases contain some form of SCN resistance. There are several sources of genetic SCN resistance, but the PI88788 source of resistance is the most widely adopted.

SCN populations have evolved tolerances to several sources of resistance in many geographies. SCN populations in these fields can now reproduce on soybean varieties with one or more resistance sources. Currently, most SCN-resistant varieties contain resistance from PI 88788, some with Peking (PI 548042), and fewer still are PI 89772.

In the last decade, Peking (PI 548042) has become a popular source of genetic resistance that remains very effective in PI88788-tolerant populations. Moving forward across the region, the Peking source of genetic resistance has demonstrated a reduction in SCN's ability to set up feeding sites and reproduce. Reducing reproduction is critical to long-term population management.

Researchers recently discovered a novel way to prevent soybean cyst nematode (SCN) from attacking soybeans. The loss of function of the GmSNAP02 gene in resistant soybean varieties like PI 90763 and PI 437654 thwarts the ability of SCN to attack the soybean plant. As Dr. Melissa Mitchum, College of Agricultural & Environmental Sciences at The University of Georgia explains in a recent article by the SCN Coalition,

“Think of it like a lock-and-key model, where SCN is the key, and GmSNAP02 is the lock. If you get rid of that lock, the nematode cannot access the plant. You make the parasite ineffective.”

The next step in SCN management will be integrating the GmSNAP02 gene mechanism into varieties that are available to plant.

Left unmanaged, SCN populations lead to a steady increase in yield loss. Reducing population densities once they have reached highly damaging levels is difficult. Scouting fields for the presence of pests and sampling fields for nematode population densities are both important management tactics.

Scouting fields for foliar plant symptomology and SCN egg cysts on roots (Figure 1) and soil sampling for SCN eggs are two critical management tools to define potential SCN populations when determining a cropping sequence and a rotation of SCN-resistant sources. In the cropping sequence, using nonhost crops and non-host cover crops and diligent weed control are key "must-do" cultural tools. Growing soybean varieties with resistance to SCN and rotating SCN sources of in-plant resistance, along with the use of nematode-protectant seed treatments, are the next steps toward reducing SCN populations.

In 2025, Saltro® seed treatment will be added to Beck's Escalate® yield enhancement system as an upgrade option to the base treatment containing Nemasect®. Nemasect alone has a 3.0 Bu./A. advantage in moderate to high soybean cyst nematode (SCN) infections.*

Superior protection from SDS without signs of plant stress, including phytotoxicity or stunting

Paired with Chitosan, a bio-stimulant and nematicide that provides superior protection against SCN and offers improved early above- and below-ground growth.

This is the most important step for all soybean growers to conduct to define their SCN populations on any field that is or will be planted with soybeans. Although these soil samples can be pulled at any time (not frozen), the most representative data will be pulled from a fall or post-R6 (full bean in the pod) sample. For growers conducting annual or system soil sampling for nutrients, this soil sample can be split for both nutrients and SCN testing.

Growers have an ally and resource at The SCN Coalition. The SCN Coalition is a public/checkoff/private partnership formed to increase the number of farmers who are actively managing SCN. Their goal is to help soybean farmers increase their yields and profit potential.

 to view laboratories that conduct SCN soil testing

For additional information on SCN Population Management, please see the 

*8-year test results (2016-2023) from 303 trial sites
Map Source: https://www.plantpath.iastate.edu/news/scn-continues-spread-us-and-canada