Soybean Fungicide Applications: A Lucrative Boost for Your Beans

Soybean Fungicide Applications: A Lucrative Boost for Your Beans

Todd Clements, a soybean grower of Morganfield, Ky., couldn’t agree more: applying a fungicide to his soybeans is a lucrative move. He has sprayed Stratego® YLD on his soybeans for the past five years at R3/R4 and has annually witnessed the rejuvenation. This season, Clements applied Stratego YLD to all of his soybean acres: 

“We really see a big yield difference from spraying Stratego YLD on our soybeans. Probably close to 8 to 10 bushel more. We've had some areas that we did not spray just to compare; we always try to do a check. We’ve had frogeye leaf spot and there's so much other disease out there, so you can see definite response in the plant right after you spray.”

How can you determine if spraying a fungicide is right for your farm? Your final decision should factor in more than weather alone.

Randy Myers, Crop Science product development manager, outlines four environmental conditions to consider:

4 factors for determining fungicide applications

  1. Moisture: Infections are more aggressive when there are high levels of moisture, which includes rainfall and heavy dew.
  2. Disease history: If disease has been a problem in the past, there is most likely already a source of inoculum for infection.
  3. Cultivar sensitivity: Some cultivars are high-yielding but more vulnerable to disease.
  4. Insecticide applications: If you are already going over the field with an insecticide, mixing in a fungicide consistently results in higher yields and increased ROI.

Bayer agronomists wanted to know as much as you do — does it really pay to apply fungicides to soybeans? We replicated field trials to test yield response to fungicides applied in soybeans. We then calculated the average yield response and average industry costs for product and application.

Of course, the bottom line will come down to a number of factors that are still unknown at the time of this writing, such as what kind of rain and temperatures will finish out the summer. What we do know is that an application of Stratego YLD in soybeans can be as profitable as it is in corn. For the past several years, soybeans treated with Stratego YLD at flowering averaged 3.25 bu/A more than untreated soybeans.* This equates to a profit of $16.41/A for $10 soybeans.

Even if the weather is going your way — an inch of rain per week, moderate temperatures, low winds, and no hail — the conditions that favor good yields are also ripe for disease. The good news is that disease pressure can be prevented. Just as fruits and veggies boost your immune system, fungicides protect soybeans from potential disease.

Still, don’t wait until the last minute when summer is in full swing to make your final decision. Get a head start and do your homework. Scouting should begin with an analysis of the past few seasons. Fields with a history of disease should be monitored first. 

Fungicide facts every grower should know

  1. Fungicides work to provide growers with valuable ROI. When commodity prices are low, it is even more important to bring in the best yield.
  2. Application timing dramatically affects performance.
  3. Fungicides can’t fix everything. If the field is suffering from a nutrient deficiency, a fungicide can’t increase yield to where it should have been. Fix the underlying problem.

Frogeye leaf spot and brown spot are two of the most prevalent diseases the Mid-South faces. Both can sneak up early, requiring earlier identification than other diseases. The two tend to begin low in the canopy and work their way through the layers of leaves.

“Since a good soybean field typically has a closed canopy by R2, the presence of frogeye leaf spot and brown spot may require an earlier fungicide application,” Myers says. “Once the canopy closes, getting the active ingredient into the understory where the pathogens are active is very difficult."

Some soybean growers apply an early-season and at-flowering fungicide application, but if you only plan to make one treatment, R3 is your best bet. This growth stage will protect the greatest percentage of your canopy.

So nail the timing. That’s critical. Then you will be rewarded with growing a plant that’s healthier, greener, and ready to reach its full yield potential.


*Assumes Stratego YLD in soybeans using industry average for product cost and assuming a tankmix with a planned application of herbicides or insecticides.

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