Flexstar® herbicide 1 pt/A, treated late to show the effect of droplet size. This is from a spray coverage trial at the York, NE, Grow More™ Experience site in July 2020.

We’ve all been there: You go to the beach for an afternoon, put on sunscreen, and think you’re all covered until you are lying in bed that night in pain because you missed a spot – ouch! While herbicide sprayer applications have little in common with a day at the beach, there is an important connection; herbicides are only as effective as their applications. Taking a few minutes to reorient yourself with the following tips might help you increase spray coverage leading to the best possible weed control this season. Note: The following are general suggestions, but as noted in the first point, always refer to spraying instructions on product labels. 

• Reviewing product labels: All pesticide labels are different and offer a one-stop-shop for critical information like crop usage, interval windows, application timing, rates, spray equipment, mixing instructions, personal protective equipment, cleaning, storage and disposal.
• Nozzle selection: The nozzle directly affects the size of the spray droplet. The product labels include instructions about which nozzle size to use.
• Nozzle care: Check each nozzle for blockage or wear before each application. Also, make sure the output is within 5% of the manufacturer’s rating for the nozzle. If necessary, clean or replace the nozzle.
• Droplet size: Read product labels to see which size is needed for application. Common recommendations include coarse- or medium-sized droplets.
• Sprayer speed: Driving at slower speeds (below 15 mph) will help keep the boom at an appropriate and consistent height. If using a rate controller, beware of increased speeds that could affect the rates.
• Sprayer calibration: Sprayer calibration provides the information you need to determine the amount of herbicide and carrier being applied per acre. Read more about the ounce calibration method from the University of Nebraska-Lincoln.
• Boom height: Keep the boom height at the minimum required to get overlapping coverage.

Agronomy Service Representative Travis Gustafson provided 2 examples of how droplet size can impact broadleaf weed control when the label is not followed in a trial at the York, NE, Grow More™ Experience site.

Here’s a summary of how the droplet size can impact weed control:

• Trial background: Flexstar herbicide was applied late when weeds were about 4-6” tall. We do not recommend this application timing but did this specifically to show the impact of droplet size in this trial.
• First photo with medium-to-fine droplets: Even with the late application, there was high crop safety and some velvetleaf, Palmer amaranth and pigweed control. The label recommendation of medium to fine droplets did lead to better coverage than the later trial.
• Second photo with ultra-course droplets: Everything else about the previous trial was the same, except that we applied ultra-course droplets of Flexstar. This application did not lead to good coverage and had increased weed pressure, especially velvetleaf.

It is important that you properly clean and reset your nozzles to the recommended size between herbicide sprays to make the most out of your applications.

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Product performance assumes disease presence. Performance assessments are based upon results or analysis of public information, field observations and/or Syngenta evaluations. Trials reflect treatment rates commonly recommended in the marketplace.

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