Factors to Consider Before Using a Soybean Seed Treatment

Updated in 2026, this version replaces the 2018 Factors to Consider Before Using a Soybean Seed Treatment.

There are many seed treatments available to manage soybean pests, but most are only effective during the first few weeks after planting. In addition, there are many products and product combinations available, which can make it difficult to understand which treatments consistently provide a positive return on investment.

This publication describes the factors to consider when making soybean seed treatment decisions. This publication discusses three major types of seed treatments: fungicides, insecticides, and nematicides.

Fungicide Seed Treatments

Fungicide seed treatments can provide protection against two different types of pathogens: seedborne fungal pathogens (e.g., the Phomopsis seed decay fungus) and soilborne pathogens that infect seedlings and roots (e.g., Pythophthora spp., the sudden death syndrome (SDS) fungus, etc.). If you are considering a fungicide seed treatment, then it’s important to know that they are more likely to provide a benefit when:

• Fields that have a history of soybean seedling diseases, SDS, and/or red crown rot

• Planting into soils below 60°F (16°C)

• Planting into compacted soils

• Seeding  rates less than 140,000 seeds per acre

• Planting in no-till or reduced tillage systems, or fields with high levels of surface residue, such as cover crops

• Fields that have a history of flooded soils

• Seeds that have high levels of seedborne fungal infestation

• Fields that are in continuous (two or more years) soybean

• Varieties that are susceptible to diseases such as Phytophthora root and stem rot and SDS are planted

Insecticide Seed Treatments

Insecticide seed treatments manage early-season insect pests, especially insects that injure soybean seedlings before growth stage V2. However, most soybean insect pests occur after this time.

Except in special circumstances, economic analyses that incorporate yield benefits and management costs show that farmers have a higher return on investment when they follow an integrated pest management (IPM) approach based on scouting and treating at insect pest thresholds. Factors like pest history, cropping patterns, and economic analyses should also factor into this decision. If you are considering an insecticide seed treatment, they are more likely necessary when:

• Soybean is planted into fields after pasture, grassland, or a Conservation Reserve Program (CRP)

• Soybean is planted into fields with a high level of decomposing organic matter (such as recently incorporated green cover crops or animal manure)

• Soybean is planted as a second-crop in a double-crop system (e.g., following wheat)

• Soybean varieties are planted that are at risk of acquiring bean pod mottle virus from the bean leaf beetle

Nematicide Seed Treatments

Nematicide seed treatments can be classified as either chemical or biological agents with varying modes of action. While nematicide seed treatments provide some early-season protection of seedling roots from nematodes, they are not meant to be a silver bullet for season-long nematode management. Consider a seed treatment as just one tool for nematode management.

The two best tools for managing nematodes remain rotating crops that are non-hosts or poor hosts to a specific nematode species and planting nematode-resistant varieties. However, repeatedly planting  varieties with the same source of resistance can lead to the selection of nematode populations that are able to reproduce and damage those varieties.

If you are considering a nematicide seed treatment, it is more likely to be beneficial when:

• Fields have a history of plant-parasitic nematodes.

• Seed treatments are combined with nematode-resistant varieties.

• A low to moderate population of plant-parasitic nematodes is present. Nematicide seed treatments are not likely to provide adequate protection when populations are high.

• Soil moisture is adequate at planting and several weeks thereafter.

Before using a seed treatment, submit soil samples to a nematode testing laboratory and consult with your extension specialist to determine if yield-limiting plant-parasitic nematodes are present and those  populations are in a range where a seed treatment may be beneficial.

Inoculants

Although not a seed treatment, inoculants may be applied to soybean seeds at planting. Soybean has the unique ability to form a symbiotic relationship with a soil bacterium, Bradyrhizobium japonicum, which forms nodules on the roots that can biologically fix nitrogen. During this process, atmospheric nitrogen (N) is converted into a form that soybean plants can use. Because of this symbiotic relationship, soybean farmers typically do not apply N fertilizer to soybean, but may consider applying soil inoculants that contain B. japonicum on or near the seed to ensure that biological nitrogen fixation occurs.

If you are considering an inoculant, they are more likely necessary when:

• Fields have no history of soybean production.

• Fields have gone 4 or more years without soybean.  

Also, be aware that:

• Tillage systems do not influence the need for inoculant.

• Some seed-applied fungicides and insecticides may not be compatible with inoculants.

• There are no known harmful effects from applying inoculants.

Agronomic Practices

It is important to remember that several agronomic practices can affect the performance of the seed treatments. Always consider the following agronomic factors when deciding whether to use seed treatments:

• Planting time. Seed treatments are most likely to be beneficial when soybean is planted early in the region. Early planting can increase the risk of wet, cool soil conditions that favor seedborne and soilborne pathogens (infection) and some insects.

• Seeding rate. The benefit of a seed treatment is most evident when reduced soybean seeding rates (140,000 seeds per acre or less) are used. In many regions, the minimum plant stand for highly productive soils is 100,000 plants per acre. Because farmers want to minimize input costs while maximizing yield, they may reduce their seeding rates and use seed treatments to help protect the stand.

Additional Risks to Consider

Repeated use of products with the same pesticide mode of action can lead to less sensitive or resistant insects and pathogens over time. Using integrated management strategies can decrease the need for seed treatments, which reduces selection pressure on insects and pathogens. Although it is easy to consider seed treatments as “insurance” for stand establishment, this practice may not be economically viable each year, and will increase the risk that pest populations will develop pesticide resistance.

Additionally, there is an economic risk to using seed treatments as they are an added expense and may not provide an economic benefit in all fields. Carefully weigh the costs and benefits of seed treatments and consider fields and conditions before deciding on any seed treatment.

The North Central Regional Committee on Soybean Diseases (NCERA-137) updates the Fungicide Efficacy for Management of Soybean Seedling Diseases publication annually. This publication rates the efficacy of fungicide seed treatments.

You can review a list of insecticide seed treatment products from the University of Wisconsin-Madison Extension.

Table 1. Risk factors that influence the need for soybean seed treatments.

Acknowledgements

Authors

Kiersten Wise, University of Kentucky; Mandy Bish, University of Missouri; Carl Bradley, University of Kentucky; Martin Chilvers, Michigan State University; Shawn Conley, University of Wisconsin-Madison; Ashleigh Faris, Oklahoma State University; Travis Faske, University of Arkansas; Horacio D. Lopez-Nicora, The Ohio State University; Dyan Mangel, University of Nebraska; Daren Mueller, Iowa State University; Edward Sikora, Auburn University; Damon Smith, University of Wisconsin-Madison; Albert Tenuta, OMAFA; and Kelley Tilmon, The Ohio State University

Reviewers

Maira Duffeck, Oklahoma State University; John Mueller, Clemson University; Boyd Padgett, LSU AgCenter; Trey Price, LSU AgCenter; Madalyn Shires, South Dakota State University; Darcy Telenko, Purdue University; and Richard Wade Webster, North Dakota State University

Sponsors

The authors thank The United Soybean Board, Grain Farmers of Ontario, and United States Department of Agriculture - National Institute of Food and Agriculture for their support.

How to cite: Wise, K., Bish, M., Bradley, C., Chilvers, M., Conley, S., Faris, A., Faske, T., Lopez-Nicora, H. D., Mangel, D., Mueller, D., Sikora, E., Smith, D., Tenuta, A., Tilmon, K. 2026. Factors to Consider Before Using a Soybean Seed Treatment. Crop Protection Network. CPN-4003. doi.org/10.31274/cpn-20190620-012.