As farmers look to push planting dates and maximize yields, seed treatments have exploded in popularity. In fact, 50% of soybeans planted in Iowa are treated, a steep increase compared with the 3% treated in the early 2000s, according to an Iowa State University study.
These additions to basic seed packages can bolster plant defenses against early-season threats and boost performance throughout the growing season.
"We know people invest a lot of time and money into their seeds," said Dale Ireland, technical product lead for Syngenta. "Seed treatments protect the rooting potential and yield potential of that crop."
However, uncertain markets mean careful consideration should be taken to make the most of additional input costs.
Picking the Right Seed Treatment
Much like seed selection, picking the right seed treatment for your acres provides the greatest return on investment. Consider field history, management systems, and seed traits when making a final decision.
"Not all seed treatments are created the same," Ireland said. "There's as much variation in the active ingredients in seed treatments as there are active ingredients in herbicides."
Fungicidal seed treatments have several application methods and classifications to be aware of, including:
In-Furrow Application: Made at planting, this treats the soil directly. It may require a higher rate of active ingredient, accord-ing to South Dakota State University Extension.
On-Seed Treatment: Applied directly to the seed, this targets pathogens as they come into contact with the seed during the first stages of germination.
Protectant Seed Treatments: Effectiveon the seed surface, these provide control over seed-surface-borne pathogens and most soil-borne pathogens.
Systemic Seed Treatments: Absorbed into the developing seedling, these inhibit or kill fungi inside the host plant. Notably, this type of treatment is used to target Pythium.
Biological Seed Treatments: These utilize organisms or natural compounds and may provide a level of protectant activity.
Early-Season Disease Protection
Disease protection is the most popular use of seed treatments. A key concern is seedling diseases, especially on farms prioritizing early planting.
In 2023, 72% of soybean seed treatments were fungicide products, according to a survey by the American Soybean Association (ASA) and the United Soybean Board (USB).
"Seed treatments don't always get the credit they deserve," said Josh Shofner, a field agronomist for Pioneer. "Genetics are big, and the way we handle the crop is huge, but seed treatments are the final step for protect-ing against seedling disease."
Early-season protection is particularly important in areas prone to long periods of cool, wet weather. These conditions exacerbate problems such as Pythium and Fusarium.
"Last year, some pockets of the Midwest saw really heavy rainfall in May and June," Shofner said. "Soybean seedling diseases were a big topic, with early damping off and young plants struggling. Seed treatments are a big option for managing that."
Nematode Protections
Nematodes remain a top yield robber in both corn and soybeans. "Nematode control is an area that's been really difficult to find new solutions for," said Cody Gray, the regional research and development head for North America at UPL. Many control options have lost effectiveness due to an overreliance on single modes of action, he explained.
Nematicide seed treatments protect the early-season plant by creating a "zone of protection" around developing roots, according to the Crop Protection Network (CPN). While they cannot provide season-long protection, pairing them with other management options may significantly increase control.
"There's no silver bullet for nematode control," said Matthew Pye, a biologicals subject matter expert at FMC. "It has to be a multi-pronged approach. Biological [nematicides] are basically new tools with a different mode of action."
Nematicides are gaining popularity, making up 34% of seed treatments used in 2023, according to the ASA/USB survey. These products are most commonly used in the southern Corn Belt.
Sudden Death Syndrome
Early-planted soybeans are particularly susceptible to sudden death syndrome (SDS), a soil-borne disease closely linked to soybean cyst nematode. There is no effective rescue treatment, and the disease can cause substantial yield loss.
Seed treatments containing fluopyrgam - a combined fungicide and nematicide - have offered effective control over SDS.
In a 2019 study by the CPN, fields with a fluopyram seed treatment saw a 35% reduction in the foliar disease index of SDS, and a 4.4-bushel-per-acre yield in-crease compared with fields treated with a commercial base seed treatment. When SDS symptoms were severe, the fluopyram seed treat-ment protected yield more than 80% of the time.
However, the CPN found the probability of seeing a notable yield bump was low when SDS symptoms weren't present.
