Recently the Environmental Protection Agency approved a Section 18 Emergency Exemption label for Vertento® Insecticide for use on sunflowers for red sunflower seed weevil management in South Dakota. This exemption is effective from July 15 to August 31, 2026.
At SDSU, we have previously tested the active ingredient of Vertento® Insecticide (isocycloseram) for the last few years. In a 2022 laboratory assay, we observed 100% mortality of a red sunflower seed weevil population that was collected from Hughes County. In field trials, isocycloseram greatly reduced the percentage of damaged seeds when compared to the untreated control. The emergency exemption for this product provides sunflower producers in South Dakota with an alternative choice to malathion.
In South Dakota, we have confirmed red sunflower seed weevil resistance to the pyrethroid active ingredients lambda-cyhalothrin, esfenvalerate, cypermethrin, deltamethrin, and beta-cyfluthrin. In addition, we received field failure reports for malathion (organophosphate) during 2025. The active ingredient isocycloseram targets insects at a different site and has a different mode of action than pyrethroids and organophosphates. This new active ingredient has the potential to effectively manage red sunflower seed weevil populations, and if used according to the label and not overused, it may slow the development of resistance to malathion.
If red sunflower seed weevils require management, we recommend a single application of either Vertento® Insecticide or malathion. If an additional application is required to reduce the red sunflower seed weevil populations, rotate to the other product to reduce the risk of resistance selection to either active ingredient. While permissible by the label, tank mixing multiple insecticide products is not recommended due to increased and/or unpredictable toxicity, risk of phytotoxicity, and product incompatibilities. As a reminder, use the rates on the malathion Section 24c and Vertento Section 18 labels found at the South Dakota Department of Agriculture and Natural Resources.
If you suspect failure of Vertento® or malathion for red sunflower seed weevil management, please contact Adam Varenhorst with SDSU Extension.
Always read and follow pesticide labels. It is your legal responsibility to adhere to any restrictions, including required minimum droplet sizes and buffer distances, and to ensure that the correct rate is being applied.
