Limited Seed Treatment Tools Increase Importance of Stewardship

- Nathan Ehresman

The modern crop-chemical registration process limits the number of available seed treatment tools and makes stewardship of existing tools even more important.

The increasing cost to obtain and maintain regulatory approvals for crop protection chemicals threatens to limit the introduction and retention of seed treatment pesticides.

By itself, seed treatment is a relatively small part of the overall global crop-protection market. The cost to develop a chemical for seed treatment alone would be prohibitively expensive. The expense and time to develop a new chemical pesticide — now estimated at $250 -$300 million and more than 10 years from laboratory to sale and distribution — requires wide market appeal for a manufacturer to achieve an acceptable return on their investment.

On top of the ever-increasing cost for new chemistry approval, the U.S. Environmental Protection Agency (EPA) is deep in the process of reevaluating existing active ingredients which have been in use for many years. As part of this process, EPA looks at the current state of science, requires new studies, and finally re-screens all existing chemicals using new methods to estimate the risk from ongoing use. The reevaluation process culminates in an updated risk-benefit conclusion for each chemical.

The EPA’s risk-benefit analysis relies, in part, on computer models that simulate exposure to the chemical on several categories such as, honeybees foraging near a field being planted with treated seed, birds that may be exposed to treated seed left on open ground, and farmers who load a planter with treated seed. Manufacturers bear the cost of defending seed treatment chemicals.

The reevaluation process requires EPA to examine all incidents that have been reported during the past 10-15 years from alleged exposure to the chemical during its use. This is why stewardship and use in a manner that prevents unintended exposure is so very important to the future of seed treatments. If a seed treatment product would be withdrawn from the market following EPA’s reevaluation, there are few products in the development pipeline to replace it.

Because of the high cost for new registration and reevaluations, there is increasing interest by manufacturers in biologicals since the time needed to develop these products for seed treatment is much shorter. Toxicology and environmental study requirements are abbreviated, which means less development cost. The EPA and the Canadian Pest Management Regulatory Agency (PMRA) have made provisions to encourage development of biorational products. These agencies have diminished the approval requirements from those that apply to conventional chemical products. One of the downsides is that biorational products are very specific in their use spectrum often targeting a limited range of pests. Conventional chemicals have much broader utility but face more intense scrutiny now and in the future.