Farmers must follow the pre-harvest intervals for soybeans that have been treated with insecticides before harvesting the treated fields, especially those fields treated in late July and August. That warning comes from Marlin Rice, Iowa State University Extension entomologist.
"Based on reports from my Extension agronomist colleagues, hundreds of thousands of soybean acres were sprayed with insecticides during July and August in Iowa for control of soybean aphids and bean leaf beetles," says Rice.
All insecticides listed in the accompanying table have at least a 21-day preharvest interval, and several have moderate intervals of 30 days and some have very long preharvest intervals of 60 days. The preharvest interval is the minimum number of days a farmer must wait before harvesting a treated crop.
Questions have been asked about who is responsible and liable for following the preharvest interval for an insecticide if it was custom applied to a farmer's field. Rice provides the following interpretation of information provided by the Iowa Department of Agriculture in consultation with the federal Environmental Protection Agency.
What are the Iowa Department of Agriculture regulations regarding this issue?
Section 206.11.3(b) (Distribution or sale of pesticides) states that "It shall be unlawful: For any person to use or cause to be used any pesticide contrary to its labeling or to rules of the state of Iowa if those rules differ from or further restrict the usage." Harvesting a crop before the interval stated on the label is illegal and may result in legal consequences for the farmer and the applicator. If the custom applicator has informed the farmer of the preharvest interval then this could mitigate any enforcement actions against the applicator.
Are there potential problems with a farmer harvesting soybeans before the preharvest interval?
Yes. The Federal Food, Drug, and Cosmetic Act, Chapter IV, Section 402(a)(2)(B) states: "A food shall be deemed to be adulterated if it bears or contains a pesticide chemical residue that is unsafe within the meaning of section 408(a)." This means that if any pesticide residue is found on harvested soybeans that exceeds the established pesticide tolerance then it is unsafe. The farmer that hauls soybeans with unsafe pesticide residues to a grain elevator is liable for delivering to the marketplace soybeans with illegal residues. Unsafe soybeans could create many problems at the grain elevator or with potential sales to international markets.
What is the solution to this potential problem?
The custom applicator should document that he or she has informed the farmer of the date of insecticide application to the field and the preharvest interval for the chemical. The farmer should determine when the preharvest interval will expire and not harvest the soybean crop before the label-stated interval. Written documentation of insecticide application date, insecticide name and rate, and harvest date should be kept as a record of field activities.