Warmer weather has finally arrived and will hopefully continue. Some areas will just be getting started, but for others, their sunflowers have been sitting in the ground for day. We hear about growing degree days (GDD) a lot with corn, but not as much with sunflowers. How many GDD are actually needed from planting to emergence for sunflowers? Are there any concerns for grower that have had their sunflowers sitting in the soil?
Emergence can vary from field to field and hybrid to hybrid, but typically it takes 206 GDD for a sunflower plant to emerge. Sunflowers can be planted in soils as cool as 45 degrees Fahrenheit (7 degrees Celsius), but won’t germinate until the soil nears 50 degrees Fahrenheit.
For more information on sunflower GDD and how to calculate go to https://ndawn.ndsu.nodak.edu/help-sunflower-growing-degree-days.html.
If you are able to get your sunflower planted early, make sure to keep an eye on them as they start emerging to know if there should be any potential stand concerns. Seed treatments, like the new Plenaris®, can help with issues such as downy mildew. Besides fungal pathogens, there are still other concerns that may arise. Cutworms, wireworms and soil crusting are just some examples that can contribute to stand loss. It is also to make sure to keep post emergent weeds under control.
Post Emergent Herbicide Spraying for Sunflowers
There are limited choices for post emergent herbicides for sunflowers and the window is small. Understanding how to stage sunflowers will help you to not get caught off guard and apply your post emergent herbicide on time.
Factors to Consider
- The early stages are considered vegatative and start with a “V: followed by the number of leaves
- When first emerged out of the ground that is considered Vegetative Emergence (VE)
- Sunflower put on two leaves at a time (V2, V4, V6, etc)
- Growing degree days (GDD) for sunflower have lower end (44 vs 50 degree F) and higher end (no top end vs 86 degree F) than corn
- Plants with the Express® trait can be sprayed from V2 to pre-bud (safe bet to have it on by V10)
- The Clearfield® train can be sprayed from V2-V8 with the Beyond herbicide at 4 oz per acre. If you have Nuseed’s Clearfield Plus hybrid, N4H470 CL Plus, you can tank-mix in a Methylated seed oil instead of non-ionic surfactant for a better weed kill.
- Zidua® is also labeled post-emerge, V2-V8, for residual control (needs to rain to activate)
With all of these products, consult your local agronomist or the label for proper rates and adjuvants.