Legend Seeds Blog

Post Emergent Herbicide Spraying for Sunflowers

SITUATION

There are limited choices for post emergent herbicides in sunflowers, and the window is small. Understanding how to stage sunflowers will help you not get caught off-guard and apply your post-emergent herbicide on time.

VE Stage (cotyledons only) V2 Stage (2 leaves) V6 Stage (6 leaves)

FACTORS TO CONSIDER

• The early stages are considered vegetative and start with a “V”, followed by the number of leaves.
• Vegetative Emergence (VE) is when the plant is first emerged out of the ground with cotyledons only and no true leaves.
• Sunflowers grow two leaves at a time (V2, V4, V6, etc.).
• Sunflowers have a lower end (44 vs 50 degrees F) and higher end (no top end vs 86 degrees F) of growing degree days than corn.

ACTION PLAN

1. Plants with the Express® trait can be sprayed from V2 to pre-bud (to be safe, apply it by V10).
2. The Clearfield® trait can be sprayed from V2 to V8 with the Beyond® herbicide at four ounces per acre. If you have Nuseed®’s new Clearfield® Plus hybrid, N4HP470, you can tank-mix in a Methylated Seed Oil instead of a Non ionic surfactant for a better weed kill.
3. Zidua® is also labeled post-emerge V2-V8 for residual control (needs a rain to activate). Zidua® will not kill any weeds that have already emerged.

SUMMARY

With all of these products, consult your local agronomist or reference the seed label for proper rates and adjuvants.

RESOURCES

https://www.ag.ndsu.edu/extensionentomology/recent-publications-main/publications/A-1331-sunflower-production-field-guide https://www.ag.ndsu.edu/weeds/weed-control-guides/nd-weed-control-guide-1/wcg-files/6-Snfl.pdf