According to the North Dakota Department of Agriculture there are currently two products with the active ingredient chlorpyrifos that are registered for agricultural crop use in North Dakota as of February 2024.
Chlorpyrifos is an important and valued tool for insect and mite control in many crops including alfalfa, field corn, soybeans, sugarbeets, sunflower, and spring and winter wheat. (NDSU photo)
In November 2023, the U.S. Court of Appeals for the Eight Circuit issued a ruling overturning the Environmental Protection Agency (EPA)'s final rule of August 2021, which revoked all food crop tolerances for chlorpyrifos.
The Eighth Circuit Court's decision was based in part on the fact that the EPA had issued a Proposed Interim Decision (PID) in 2020, which included 11 chlorpyrifos crop uses that the EPA determined met safety tolerances. Before the PID could be finalized, the U.S. Court of Appeals for the Ninth Circuit issued a ruling ordering the EPA to either amend or revoke chlorpyrifos food tolerances and gave the EPA 60 days to comply.
The EPA revoked all chlorpyrifos food tolerances in its final rule in August 2021 (effective February 28, 2022). The Eighth Circuit Court held that the EPA could have issued a PID amending tolerances despite the short turnaround time and therefore vacated the order to revoke all food crop tolerances.
"Because of the Eighth Circuit Court's ruling, food crop tolerances are restored and producers can now use currently registered chlorpyrifos products on all crops with reinstated tolerances, consistent with directions for use on those product labels," says Janet Knodel, North Dakota State University Extension entomologist.
According to the North Dakota Department of Agriculture Pesticide Product Search site, located at https://www.kellysolutions.com/nd/searchbychem.asp, there are currently two products with the active ingredient chlorpyrifos that are registered for agricultural crop use in North Dakota as of February 2024.
"Those products are Pilot 4E, a liquid formulation used primarily as a foliar insecticide in several crops, and Pilot 15G, a granular formulation used as an at-plant band treatment for control of soil dwelling insects, notably sugarbeet root maggot in sugarbeets," says Mark Boetel, NDSU School of Natural Resource Sciences professor of entomology.
"Be sure to check with your state's department of agriculture for registered chlorpyrifos products," advises Knodel. "Even for registered products, availability may be limited in 2024."
"Chlorpyrifos is an important and valued tool for insect and mite control in many crops including alfalfa, field corn, soybeans, sugarbeets, sunflower, and spring and winter wheat," says Adam Varenhorst, South Dakota State University Extension entomologist. "This has the potential to be beneficial for producers, especially with the management of certain insecticide resistant insect pests, including pyrethroid resistant soybean aphids, pyrethroid resistant red sunflower seed weevils in South Dakota, and insect pests for which there is no other effective option."
"As a reminder, read, understand and follow the label directions for these products regarding registered crops, application methods, application rates, preharvest intervals and the total seasonal limits for active ingredient per acre. Also, be sure to follow personal protective equipment (PPE) requirements on the product labels, as well as environmental hazard, spray drift mitigation, and agricultural use language," cautions Andrew Thostenson, NDSU Extension pesticide program coordinator.
Chlorpyrifos is highly toxic to bees that are directly exposed to the treatment or to remaining residuals on blooming crops and weeds. Per the Environmental Hazards section on the label,do not apply this product or allow it to drift to blooming crops or weeds if bees are visiting the treatment area.
"This means that application timing must occur when pollinators are not actively foraging on the crop and will not be exposed to residuals during foraging activities," says Patrick Beauzay, NDSU Extension entomology research specialist. "Application of chlorpyrifos insecticides should occur in the evening after 6 p.m. Do not apply chlorpyrifos or any other pesticide during temperature inversions, as severe off-target drift is likely to occur under these conditions."
"The future of chlorpyrifos is still uncertain. While registered product and crop uses are again legal, the EPA will continue to evaluate chlorpyrifos food tolerance and environmental safety as required by law during the registration review process," says Thostenson.
The EPA likely will issue a new PID for the 11 identified crops from the 2020 PID, including alfalfa, soybean, sugarbeet, and wheat (spring and winter), which could include amended tolerances and new use restrictions, says Knodel. Crop uses that were not identified in the 11 uses specified in the PID are especially uncertain and could have their tolerances revoked entirely. Sunflower and corn were not included in the 11 crop uses.
Producers, crop consultants, pesticide applicators, commodity groups and other stakeholders can and should provide comments to the EPA when they publish decisions, recommends Knodel.
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