Posted on Oct 21, 2014 by Michael Gray

US EPA Concludes Neonicotinoid Seed Treatments of Negligible Benefit to Soybean Production

On October 15, 2014, the US Environmental Protection Agency issued a report on the benefits of neonicotinoid insecticidal seed treatments to soybean production in the United States. Neonicotinoid insecticidal seed treatments include imidacloprid, thiamethoxam, and clothianidin. The analysis concentrated only on the potential benefits of imidacloprid and thiamethoxam used as seed treatments. Although clothianidin is registered for use as a soybean seed treatment, the authors of the report considered its use “minor” as compared with the other two neonicotinoids. Provided below are interesting pieces of information that I pulled directly from the report.

The authors of this EPA report acknowledge that use of neonicotinoids within soybeans is largely prophylactic — an insurance based form of pest management. In their analysis they estimate that insecticidal seed treatments cost on average approximately $7.50 per acre. They also point out that foliar insecticides labeled for use in soybeans generally cost less than $7 per acre (11 insecticides identified). In addition, the authors of this EPA report make the following assumptions on page 10:

Some of these assumptions can be challenged, especially on very large farms across the Corn Belt in which many producers rely upon aerial applications of pesticides rather than making their own ground-based treatments. Additionally, the use of fungicides although increasingly common in recent years, is not routine within every Midwestern soybean field. Therefore, application of an insecticide and fungicide tank mix should not be considered a given on most soybean fields, nor should that of a herbicide and insecticide combination. The optimum time to apply a herbicide for weed control can vary considerably from that to deter insect damage.

Nonetheless, this informative report raises considerable doubt regarding the economic benefits of these insecticidal seed treatments to soybean producers. The use of insecticidal seed treatments within the soybean production system clearly functions as an insurance-based form of pest management. For large commercial farms across the Midwest landscape, many producers typically do not scout soybean fields and utilize economic thresholds to make management decisions for insect pests. Over the years, producers could save on insecticide costs within many Midwestern soybean fields by only treating when economic levels of a given insect pest surface. Yet, the long term trend regarding insect management within large-scale commercial corn and soybean production systems reveals an increasing reliance on product-based inputs (insecticidal seed treatments, Bt hybrids) versus labor and management costs (scouting and use of economic thresholds). It will be interesting to see if US EPA considers a similar analysis for these insecticidal seed treatments in corn production systems.

Mike Gray

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