Post Emergent Herbicide Spraying for Sunflowers
June 12, 2017
It wasn’t too long ago that parts of Western ND and SD were in a freeze warning and sunflowers were slow to come out of the ground. If you were fortunate enough to catch a rain with your sunflower pre-emergent herbicide your fields may not have many weed issues. Most sunflower hybrids in 2017 have either the Clearfield® trait or Express®, allowing a grower to spray in-season for broadleaves. The recent heat has raised our soil temperatures dramatically over the past 10 days, causing the sunflowers to grow fast. They keep growing at cooler temperatures than corn (44 vs 50 degrees F) and continually add on Growing Degree Units over 86 degrees, even when corn shuts down. Keep checking your sunflowers to make sure you don’t miss your window to spray as any unwanted green growth is just taking away from what matters most, especially since a lot of the Dakotas are in a drought right now.
If your sunflower hybrid has the Clearfield® trait then you will be spraying 4 oz of Beyond with an NIS from the V2 to V8 stage for grasses and broadleaves.
Express® offers growers a little wider window as you can spray from V2 to pre-bud at .25 to .5 oz per acre with MSO. Pre-bud means all the vegetative stages that occur before R1, which is when the top center part of the plant starts forming a little head versus just a cluster of leaves. There is not a set number of vegetative stages for a sunflower (depends on weather, the hybrid, etc), so it’s a safe bet to have your Express® application on by V8/V10. Also note that Express® has no activity on grass weeds.
The BASF herbicide Zidua received a supplemental sunflower label a couple of weeks ago, allowing growers to put down a residual pre-plant (can’t be incorporated), pre-emerge or post from V2-V8 (avoid application during soil emergence through cotyledon). This is another great option to have in the toolbox for sunflowers, especially if you have a waterhemp or palmer amaranth issue. Do NOT tank-mix Beyond and Zidua together, the mix gets a little too hot for sunflowers to handle.
With all of these products, consult your agronomist or the label for proper rates and adjuvants.
DuPont™, Express® and ExpressSun® are registered trademarks of of E.I. du Pont de Nemours and Company. Clearfield® and Beyond® herbicide are registered trademarks of BASF.
Reference: Alison Pokrzywinski | Nuseed Sunflower Product Manager