In the central Corn Belt of the U.S., western corn rootworm (WCR) (Diabrotica virgifera) is widely regarded as the most significant insect pest in corn. This beetle is often called “billion-dollar bug” due to damage caused by adults and larvae. This yield-limiting pest requires an effective combination of integrated pest management (IPM) strategies, including use of foliar-applied insecticides like Steward® EC insecticide for adult control.
Steward EC insecticide delivers reliable control of WCR when applied properly. Primary exposure is through ingestion with some contact activity. Adult WCR behaviors - feeding, egg laying and mobility - are affected within zero to four hours of ingestion, and this product resists wash off once dried. There is minimal impact to many key beneficial insects and predators, and there is no flaring of spider mites. Steward EC insecticide has been formulated to help eliminate mixing, handling and clean up issues and contains both an oil solvent and surfactant characteristics for excellent crop protection.
An effective and properly timed foliar insecticide application of Steward EC insecticide can suppress the number of eggs laid and reduce potential WCR larval feeding problems in the future. Three factors are important to consider when applying Steward EC insecticide:
- Proper Timing: Treatments are usually started when more than 10% of the females are gravid. It is not advisable to make treatments too early since more females will emerge to lay eggs and newly emerged silks and foliage will not be protected. It is not advisable to make treatments too late since egg laying will already be complete.
- Good Coverage: Because this product needs to be consumed, it needs to get where the adult WCR are feeding. It is recommended that 3-5 gal./A are applied by aerial applications.
- Proper Rate: Field efficacy trials have shown Steward EC insecticide provides excellent knockdown and control rates of 6-10 fl. oz./A. If high adult WCR numbers are present, longer residual control is needed so the higher rate should be used.
STEWARD EC INSECTICIDE IS HIGHLY EFFECTIVE
The active ingredient in Steward EC insecticide, indoxacarb, has selectively low dermal and oral toxicity to mammals. Indoxacarb works primarily through ingestions, breaking down into a highly toxic metabolite inside the gut. Thus, Steward EC insecticide provides fast and long-lasting control of adult corn rootworms.
Economic thresholds and application timing: Economic thresholds vary with location, cropping history and corn variety, specifically regarding traited hybrids. In general, however, treatment is warranted when there are one to two beetles per plant in continuous corn. Steward EC insecticide should be applied when 10% of females are gravid, keeping in mind that the goal is to reduce the number of eggs laid in the soil.
Adult foliar-applied insecticide treatments such as Steward EC insecticide can drastically reduce WCR egg numbers and ultimately larvae the following year. The research trial below shows a Steward EC insecticide application made the prior year can reduce larval feeding in conventional corn (0.5) to similar levels of just using Bt traited corn (0.47).
The EPA label for Steward EC insecticide contains the following statements: This product is highly toxic to bees exposed to direct treatment on blooming crops or weeds. Do not apply this product or allow it to drift to blooming crops or weeds of bees are foraging the treatment area.
Asana® XL insecticide, Brigade® 2EC insecticide/miticide, Pilot® 4E insecticide, Penncap-M® insecticide, Voltage® insecticide and Warrior II with Zeon Technology® insecticide are Restricted Use Pesticides. Always read and follow all label directions, precautions and restrictions for use. Some products may not be registered for sale or use in all states. FMC, the FMC logo, Brigade and Steward are trademarks of FMC Corporation or an affiliate. Asana is a trademark of Valent U.S.A. LLC Agricultural Products. Onager is a trademark of Gowan Company, LLC. Pilot is a trademark of Gharda Chemicals Limited. Voltage is a trademark of Innvictis Crop Care, LLC. Warrior II with Zeon Technology insecticide is a trademark of Syngenta Crop Protection, LLC. Penncap-M is a trademark of United Phosphorus, Inc. ©2025 FMC Corporation. All rights reserved. 99_24-FMC-3456 05/24
