Tip •  2024-03-19

Is it too cold to spray?

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frost on wheat

Making plans for early spring weed control? We’ve compiled our recommended best practices and tips to help farmers make the most of their herbicide applications this spring. 

When is it too cold to spray?

  • Waiting until nighttime temperatures are above 5°C will improve product efficacy and limit crop response issues, including crop injury
  • Avoid spraying directly after a frost, wait at least 24-48 hours after the last frost
  • Target mid-day application when it’s warmer and sunnier to optimize product performance
  • Check with the product manufacturer when tank mixing a fungicide in an early-spring cereal herbicide application to avoid crop injury

Winter wheat reminders

Farmers will experience less crop response and better product efficacy when crops and weeds are actively growing. Just like winter wheat, some winter annual weeds, including common chickweed like cooler temperatures too. The winter wheat weed management challenge comes down to prioritizing winter annuals that are already growing and establishing themselves in the crop and waiting for spring annuals to emerge. Farmers need to ask themselves what types of weeds they need to prioritize – is there a sense of urgency to remove early competing weeds or wait to target later season weeds?

Burndown basics

The best start to the growing season is a clean field. Reducing weed competition offers crops their best chance at establishment and the access they need to nutrients, moisture and sunlight. An early-season corn or soybean burndown pass is the best way achieve a clean field ahead of planting.

Variable spring weather can make application timing a challenge. If spring weather is favourable, fields can start greening up early, including weed growth. Early weed emergence can create urgency, especially as they advance and become established. Its important farmers monitor early season weed growth to stay ahead of problem winter annuals or perennial weeds and prevent them from getting too far ahead before a burndown application.

An early-season burndown is the ideal opportunity for farmers to add a residual herbicide for extended weed control. Adding a residual not only helps with weeds but gives farmers more flexibility to manage their busy spring workloads. The assurance of a residual means farmers can prioritize planting, knowing early-season weeds are under control. This is especially helpful with herbicide tolerant crops where farmers can revisit the field with a post-emergence application to catch any weed escapes or later season growth.

Early-season weed control reminders

  • For those farmers who prefer to delay applications until they are certain all the weeds have emerged, remember, that strategy can be very costly as weeds that emerge with the crop result in the highest yield losses.  Managing weeds early is part of a strategy to optimize yields and returns. Tank mixing with an additional effective mode of action and adding a residual herbicide reduces the restrictions on application timing and allows for a wider, earlier application window and more flexibility when it comes to managing acres.
  • Always start with a clean sprayer. This is especially important for farmers planting Enlist E3™ soybeans. Enlist E3 soybeans are not tolerant to dicamba herbicide, and severe crop injury can occur.

Questions about cold weather applications, recommended tank mixes or weed control for your fields? Talk to your local retailer, agronomist or Corteva Agriscience Retail Territory Manager.