Soybean fungicides: By ground or by air?

Many soybeans that were planted in May and early June are now entering the optimum application fungicide timing window of R3-R4 stage. In areas with recent rains, many retailers and growers planning to use ground application may struggle to get across wet fields.  

Many growers and retailers often use ground application as the means for applying soybean fungicides. However, using aerial application to apply fungicides in soybean can also be very effective. Airplanes or helicopters that are properly calibrated can get good coverage of the soybean canopy. The downforce and air pushed into the canopy can indeed provide fungicide coverage into the lower soybean canopy and provide excellent disease protection and yield results. Regardless of how you apply soybean fungicides, it is important to apply Revytek^®, Veltyma^®, or Priaxor^® in soybeans in a timely fashion during this R3-R4 growth stage. 

If applying soybean fungicides with a ground rig:

• Be sure to clean out your sprayer. One of the worst mistakes that can be made is to make a fungicide application with a machine that has herbicide residues in it during the reproductive stages of soybean growth (especially if the last products sprayed were for corn)
• I suggest using 15-20 GPA to maximize the coverage of the soybean canopy.
• Choose spray tips that provide medium/coarse droplets and optimize coverage (twin-fanfan nozzles or nozzles used for Liberty applications are often good options)

Some considerations when applying by air:

• Use a minimum of 2 gallons per acre. Due to the speed of application and droplet dispersal, 2 GPA can look very similar if not better in coverage to a 15 GPA application by a sprayer on the ground.
• Some aerial applicators will apply 3 GPA as well, which can also provide additional coverage. If using foliar nutrients as a tank-mix partner, I often recommend 3 GPA if the aerial applicator will do so to aid in mixing and application
• Utilize adjuvants. Because droplets from aerial application are often more fine, using oil based adjuvants help reduce evaporation of the droplet prior to hitting the soybean leaf. Adjuvants have also been shown to help improve deposition into the canopy

Lastly, not placing fresh wheel tracks in your field can have some advantages too. Soybeans that are run down by tires at the R3 growth stage typically will not recover, and it is too late for the neighboring plants to compensate for the loss of the plant that was run over. For more information on this, see the Purdue article here: https://www.extension.purdue.edu/extmedia/SPS/SPS-103-W.pdf

Whether applying by air or by ground, the optimum timing for Revytek, Veltyma, or Priaxor in your soybean fields are upon us. On average, soybeans progress from the R2 (full flower) growth stage to R4 (full pod) in approximately ~19 days. Once pods are visible in one of the top 4, it is time to spray soybeans with fungicides. If you haven’t already started scouting, take some time over the next 10-14 days to check your soybean fields for Revytek, Veltyma, or Priaxor applications.

Reach out to your local BASF representative with any questions on BASF fungicides or fungicide timing in soybeans!

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