top of page
  • Writer's pictureRachel

Our Soybean Fungicide Talking Points

Each year we discuss the importance of using foliar fungicides in soybeans, and this year is no different. Through several years of testing products and timings, we are confident in our recommendation of a fungicide application on your soybeans. This blog will cover what we recommend in a fungicide application, and what results we have seen over the years.

1. We never mean just fungicide.

In all our trials, we are talking about the combo of fungicide and insecticide. In fact, any response we have seen from fungicides is actually the response from both fungicide and insecticide. The combination of these two provide the most health benefit to your plant by combating disease, stopping defoliation, and promoting overall plant health. It is exceptionally seldom that we would ever recommend applying fungicide and no insecticide. If you are going over it once, you might as well add in some insecticide and get the most bang for your sprayer pass.

2. Our 5-year results.

In 2019, we saw a 6 bushels per acre increase when using a fungicide/insecticide combo. That was identical to our five year average increase of 6 bushels per acre. We’ve seen as high as an 11 bushel per acre increase in 2016, and as low as 3 bushels per acre in 2017.

Using this five year average of six bushels per acre, a soybean price of $8.35, and a application cost of $28.50 (average cost of commonly used fungicides and insecticides, plus aerial application cost), we would see a return of over $21 per acre. In fact our breakeven is only 3.4 bushels, which we have achieved every year of the last 5 years. These economics are sound and give you the best chance of not only a good return on investment, but keeps our potential for high yields.

3. When fungicides and insecticides can help.

We aren’t here to tell you that the results of a fungicide and insecticide application are universal. But over the last five years we have found them very consistent.

This year we have seen a fair amount of threshold insect pressure from Japanese beetles, cloverworms, and likely to see threshold levels from stink bugs in a few weeks. The pressure is there to see a good return for insecticide applications.

What about fungicide? Remember, only fungal diseases can be controlled with foliar fungicides. Things like bacterial blight, or soybean vein necrosis are not fungal diseases and cannot be controlled. It’s important to scout your fields and get a good understanding of what diseases are present. If you see anthracnose, cercospora, frogeye, or Septoria, you are in luck. All of those diseases can be controlled by a fungicide application. We often get asked when planes start flying “Are disease pressures at threshold?” That is usually dependent on the field. It’s important to not only look at what current disease levels are, but to take an educated guess of what disease levels might be in a week to 10 days depending on what the weather is doing. Lately we’ve seen a consistent pattern of rain which is conducive to fungal growth. Given these conditions, we will see an increase in disease levels in the next week. Which brings us to our next main point---timing.

4. Timing

The greatest yield response to foliar fungicide applications is at R3. If you are at R3 (beginning pod formation), it’s time to get going on your applications. This window will provide your best return, and in many cases with fields approaching or already at threshold levels for insect pressure, the time is now to control. (We do have to consider since we are applying both fungicides and insecticides together, we many not be able to perfectly time both applications to meet their respective threshold levels. Sometimes, we may have to apply one a little early, to meet the demands of the other. It’s all about balance) Take a walk through your fields and look at the four uppermost nodes that have a fully developed leaf. If you find a pod on any of those that is at least 3/16th of the inch long, you are at R3.

As always talk to one of our agronomy team with any questions on products or timing!

124 views0 comments

Recent Posts

See All


bottom of page