SUNFLOWER AGRONOMY ALERT – Herbicide Spraying Time!
June 17, 2016
Recent rains and warm weather mean that the 2016 crops have finally taken off and are growing like weeds! No pun intended, but chances are when the crops are growing well in early summer, so are the weeds. Time to take advantage of our long summer days (the ones that aren’t windy) and spray. If you were able to plant a sunflower hybrid with either Clearfield® or Express® tolerance, then you have a few more options to help control some of the tougher broadleaves.
If your sunflower hybrid has the Clearfield® trait then you will be spraying 4 oz of Beyond with an NIS and a nitrogen-based fertilizer anywhere from the V2 to V8 leaf stage (V stands for vegetative). Be wary of temperatures and humidity when you spray, if there is a combined total of 135 or greater for temperature and humidity then you better park the sprayer until a cooler temperature later in the day.
Express® offers growers a little wider window as you can spray from V2 to pre-bud at .25 to .5 oz per acre with 1 pt/acre 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. Express® has no activity on grass weeds. If you also need a grass herbicide, a separate application is recommended for maximum control one day before or 7 days after Express®. However, if a grower wants to tank-mix, make sure that they increase their grass herbicide by 1-2 oz per acre to adjust for some antagonism.
With both of these products, consult your agronomist or the label for proper rates and adjuvants. Remember, the larger the sunflower plants, the larger the weeds will be as well.
For staging a young sunflower plant:
A sunflower plant will grow two leaves at a time. After it emerges there will be two cotyledons (not to be counted as leaves). Next the plant will shoot out two leaves opposite sides from each other. Once the leaves have reached 1 ½ inches it is considered a “true leaf” and can be counted as a stage. This would be considered V2. For every two new leaves that are at least 1 ½ inches, this is another stage. So a plant with 4 leaves would now be V4, etc.
Click the links below to view: Clearfield® and Express® tech sheets, the DuPont™ rebate form for Express® and our weed comparison chart highlighting Clearfield® and Express®. The DuPont™ form only highlights ND, SD and MT, but I have confirmed with a DuPont™ representative that MN growers are included in the rebate also!
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.