The Importance of Using the Right Corn Herbicide Rates

Something went wrong. Please try again later...
Evaluating weed control

As you help your customers navigate supply chain issues this season, you may have some corn farmers who are considering cutting their herbicide rates. With certain products in short supply, it may seem like a good idea to reduce rates to make do with less and possibly save some money. However, doing so could set those farmers back with their weed control for years to come.

Knowing this, we have some thoughts on how you can navigate those conversations with your customers to help them get the most out of their weed control programs despite the challenges 2022 has in store.

Why Not Cut Herbicide Rates?

Cutting herbicide rates might work out for farmers in the short term, but it’s important to remind them that action can have serious consequences in the long term. For example, reduced rates of preemergence herbicides may easily control early season weeds, but the length of the residual activity may suffer. In turn, the postemergence application has to work harder to control any additional weed flushes. This can lead to those weeds growing resistant to those postemergence chemistries further down the road. Using the right rates helps extend the life of the active ingredients farmers rely on.

In addition, any weeds the program does not control will be left to go to seed in the field. This will add to the weed seedbank and, depending on the species, could negatively impact a farmer’s weed control for years to come. For example, just one female waterhemp plant can produce up to 1 million seeds. Up to 120,000 of those seeds may still be viable in the seedbank four years later.1

Finding Alternatives

Even though you and your customers know how important it is to cut down on the weed seedbank and mitigate herbicide resistance in their cornfields, it might feel like they have no choice but to cut herbicide rates this year. The supply chain issues are unprecedented, and it’s likely confusing for farmers. That’s why it’s so important to help them work with the products and practices that are available to them.

That could mean finding alternative weed control solutions if the ones they typically use are in short supply. If, for example, you have a customer who typically relies heavily on a postemergence chemistry that is hard to get, maybe you help them switch things up with a heavier emphasis on preemergence residual herbicides. 

Products with Group 15 active ingredients are good for extended residual control this season. Resicore® herbicide and SureStart® II herbicide are two Group 15 options from Corteva Agriscience for corn farmers. Both solutions contain three modes of action and offer application flexibility — they can be applied anywhere from preplant to postemergence on corn up to 11 inches tall. We recommend starting strong with a preemergence application of SureStart II, followed by a timely postemergence application of Resicore.

It’s always advisable to use a program approach with multiple passes and several modes of action when possible. However, with the extraordinary circumstances this year, it’s also advisable to help your customers make the most of any cultural practices they’re able to use to manage weeds. Those techniques could include tillage, crop rotation, planting cover crops and hand-picking weed escapes before they go to seed.

Maximize Herbicide Applications

Getting the maximum results from their herbicides is paramount for farmers, especially in the current climate. If your customers do their own applications, it’s a good idea to give them a few helpful reminders for success:

  • Preparing Equipment — Having sprayers calibrated and ready to roll with the proper nozzles can help ensure good application coverage and control.
  • Getting the Timing Right — Knowing which weeds need to be controlled and when they are likely to emerge can help dictate timing. In addition, understanding how long residual activity is expected to last should be considered. Finally, it’s important to remember residuals will need about ½ to 1 inch of rain to activate, so farmers should take the forecast into account when scheduling applications.
  • Mixing Correctly — A smooth tank mix is also essential for getting the most out of any weed control chemistries. Following the right order can help farmers ensure the herbicides get into the field instead of stuck in the tank.
  • Using Adjuvants — Just as farmers should avoid cutting herbicide rates, they should avoid cutting adjuvants. The right adjuvants can help herbicides work their best, especially in difficult weather conditions like drought.


Visit the corn herbicides portfolio page to find suggested use rates and application timing for the powerful solutions from Corteva Agriscience. You can also talk with your local Corteva Agriscience territory manager about which products can work best for your customers’ fields.

1Bradley, K., and M. Bish. 2018. Waterhemp Management in Soybeans. https://weedscience.missouri.edu/publications/50737_3_TA_FactSheet_Waterhemp.pdf

Resicore®, Resicore XL and SureStart® II are not registered for sale or use in all states. Resicore, Resicore XL and SureStart II are not available for sale, distribution or use in Nassau and Suffolk counties in the state of New York. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. Always read and follow label directions. 

Inputs & Insights

Receive the latest retailer tips and product information in your inbox.

Browse Inputs and Insights

Subscribe to Inputs & Insights