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Insecticides & Miticides

News Release: FMC Corporation Introduces New Tool in Battle Against Resistant Western Corn Rootworms

Steward® EC insecticide gains EPA registration for use in field corn. 

PHILADELPHIA, February 22, 2018 – Corn growers have a new option for protecting input investments from resistant Western corn rootworm (WCR) beetles. Steward® EC insecticide from FMC has now received registration approval for use in field corn from the U.S. Environmental Protection Agency (EPA). State registrations for Steward EC insecticide for use on field corn are pending. This new addition to comprehensive integrated pest management (IPM) programs effectively controls yield-robbing WCR beetles and other lepidopteran pests.

“Western corn rootworms are one of the most destructive corn pests in the United States, taking a substantial toll on yields and profits through silk clipping and ineffective management costs,” said Sally Feeley, insecticide product manager, FMC. “Steward EC insecticide is the missing link for resistant WCR beetle control, something that has eluded growers due to overreliance on existing products and Bt traits in corn-on-corn acres.”

Steward EC insecticide demonstrated effective WCR beetle control in numerous field studies conducted in various Midwestern states from 2013 to 2016. Results show that Steward EC insecticide at 6 and 10 fluid ounces per acre provided 79 percent and 84 percent control of beetles, respectively. These evaluations were made from two to five days after treatment to 19 to 24 days after treatment.

The active ingredient in Steward® EC insecticide, indoxacarb, is an integral part of an IPM plan to manage WCR resistance. Resistance has been reported in the previous three major insecticide classes used for WCR beetle control: organophosphates, carbamates and pyrethroids. However, indoxacarb has no known WCR resistance or decreased sensitivity. By working through ingestion and contact activity, Steward EC insecticide provides fast-acting protection within four hours of ingestion to prevent impact on yields from reduced pollination because of silk clipping. It is also easy on beneficial mites and insects, preventing flares from spider mites and other insects.

Steward EC insecticide is easy to handle and apply and provides up to two weeks of residual control. Steward EC insecticide features a short re-entry interval of 12 hours and rapid dispersal in hard or soft water. Data has also shown that Steward EC insecticide is rainfast within two hours.

Western corn rootworm photoSteward EC insecticide has a unique mode of action shown to be effective in controlling Western corn rootworm adults in field trials. At high infestation levels, adult beetles can cause damage by feeding on silks, which affects pollination and seed set. 


Media contacts
Lisa Homer, 215-299-5870,
Joan Olson, 612-808-8406,

About FMC
For more than a century, FMC Corporation has served the global agricultural, industrial and consumer markets with innovative solutions, applications and quality products. On November 1, 2017, FMC acquired a significant portion of DuPont's Crop Protection business. FMC employs approximately 7,000 people throughout the world and operates its businesses in two segments: FMC Agricultural Solutions and FMC Lithium. For more information, visit


Always read and follow label directions. FMC acquired one or more of the referenced studies from DuPont as of November 1, 2017. As of November 1, 2017, the USEPA registration for DuPont™ Steward® EC insecticide has been sold to FMC by DuPont. FMC and Steward are trademarks of FMC Corporation or an affiliate. ©2018 FMC Corporation. All rights reserved. 18-FMC-1742 02/18


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