Soybean aphid (Aphis glycines) can cause significant yield reductions in Minnesota soybean production. Research from the University of Minnesota and neighboring Midwestern states has documented yield losses of up to 40% under severe infestations when aphid populations are left unmanaged.

This season has been particularly dry across several soybean-producing states, including South Dakota, Nebraska, Kansas, Arkansas, Kentucky, Missouri and portions of southern Minnesota. These environmental conditions could increase the risk of soybean aphid outbreaks during the 2026 growing season. Soybean aphids generally benefit from warm and dry conditions, and regional factors such as overwintering populations and passive movement from southern states can also contribute to aphid pressure in Minnesota soybean fields.

Because of this, growers should remain alert and continue to scout soybean fields closely, especially those planted early.

Scouting and Thresholds

Based on recommendations from the University of Minnesota Extension and neighboring Midwestern states, growers should consider treatment when fields reach an average of 250 aphids per plant, more than 80% of plants are infested and aphid populations are actively increasing. This threshold provides time to schedule insecticide applications before populations reach economically damaging levels.

As a general scouting recommendation, growers should evaluate at least 11 plants per 50 acres using a “W,” or “Z” scouting pattern to obtain a representative picture of field conditions.

What Minnesota soybean research is showing about insecticide performance

Koch and Ribeiro (University of Minnesota, 2025) evaluated insecticide performance under relatively low to moderate soybean aphid pressure, with populations averaging approximately 60 aphids per plant before treatment. Several insecticides, including Endigo ZCX (neonicotinoid + pyrethroid), Sefina (pyropene), Renestra (organophosphate + pyrethroid), Transform (sulfoximine), Ridgeback (sulfoximine + pyrethroid), and Sivanto Prime (butenolide), maintained aphid populations near zero through 21 days after treatment (Figure 1). In contrast, Warrior II (pyrethroid) did not adequately control soybean aphids, and aphid populations increased to nearly 450 per plant, exceeding those observed in the untreated check. These results demonstrate that pyrethro-only insecticide programs may not provide consistent soybean aphid control in Minnesota soybean production.

Lueck and Whitmore (Next Gen Ag LLC, 2024) evaluated insecticide performance under substantially greater soybean aphid pressure, with aphid populations averaging approximately 367 aphids per plant before treatment, well above the University of Minnesota economic threshold of 250 aphids per plant. Under these conditions, differences among insecticide programs became even more apparent (Figure 2). Products containing alternative modes of action, including Sivanto Prime (butenolide), Transform (sulfoximine), Sefina (pyropene), Endigo ZCX (neonicotinoid + pyrethroid), and Renestra (organophosphate + pyrethroid), maintained aphid populations below approximately 50 aphids per plant 14 days after treatment and were generally associated with the greatest soybean yields, ranging from approximately 65 to 70 bu/acre. In contrast, pyrethroid-based treatments, including bifenthrin and zeta-cypermethrin combinations, resulted in aphid populations exceeding 200 aphids per plant and lower soybean yields, in some cases near 55 bu/acre.

Together, these soy checkoff-supported studies reinforce current University of Minnesota Extension recommendations encouraging growers to avoid repeated reliance on pyrethroid-only insecticide programs and to rotate insecticides from different IRAC groups to improve soybean aphid management and delay the development of insecticide resistance.

Dangers of treating too early or using the wrong insecticide

Treating soybean aphids before the economic threshold is reached can create additional management problems. Early insecticide applications may reduce populations of beneficial insects and natural enemies that help suppress soybean aphids naturally throughout the season. In some situations, this can increase the risk of later aphid outbreaks.

In addition, applying insecticides when aphid populations are not present or are below threshold may create a false sense of security. Residual activity from insecticides is limited, and soybean plants may remain unprotected later in the season if aphid populations increase after the insecticide activity declines.

Selecting the appropriate insecticide is also important. Research from Minnesota continues to show that relying only on pyrethroid insecticides may not provide consistent soybean aphid control under all conditions.

Take-home message

The 2026 growing season has the potential for increased soybean aphid pressure in parts of Minnesota. As always, the key to successful soybean aphid management is consistent scouting and informed decision-making. Growers should monitor fields carefully, follow established economic thresholds, and select insecticides based on field conditions, crop stage and effective IRAC group rotation.

Effective soybean aphid management cannot rely on only one or two chemical options. Rotating insecticides with different modes of action is important for maintaining effective control and reducing the risk of insecticide resistance in Minnesota soybean production systems. There are also resistant and tolerant varieties, crop rotation and some cultural management practices that could be used. The Minnesota Soybean Research & Promotion Council (MSR&PC) will continue to explore these options and make sure to share this information with our farming community.

Disclaimer

Trade names and commercial products are mentioned solely for educational and research-based discussion. MSR&PC does not endorse or guarantee any specific product or company. Products discussed in this article are referenced based on publicly available research and field evaluations. Always read and follow pesticide label directions. For field-specific recommendations, consult local agronomists, University Extension specialists, or Extension educators.

References

Ribeiro, A. V., and R. L. Koch. 2025. Evaluation of insecticides for management of soybean aphid, 2025. Arthropod Management Tests 50(1): tsaf146.
Evaluation of insecticides for management of soybean aphid, 2025

Lueck, B., and J Whitmore. 2024. 2024 Aphid, Plant Health and White Mold Industry Program Yield Impact in Soybean. Minnesota Soybean Research & Promotion Council.
2024 Aphid, Plant Health and White Mold Industry Program Yield Impact in Soybean