Answers are from the Indiana certified crop adviser panel: Betsy Bower, Purdue Extension senior research associate, West Lafayette; Abby Horlacher, Nickel Plate Consulting, Frankfort; and Brian Mitchem, Farmer 1st Agronomy Consulting Services, Decatur.

 

Some people say don’t spray soybeans with fungicide unless you see disease signs. Others say spraying is worth 3 to 4 more bushels per acre. Should we spray? If so, when?

 

Bower: I have worked with customers on both sides of the discussion. To keep our current fungicides as valuable tools for disease protection, we should see disease before we spray. When you scout for disease, look at the plant from top to bottom for disease lesions. Of course, frogeye leaf spot continues to be the most yield-impacting foliar disease in susceptible soybean genetic lines. But we can see yield damage from septoria brown spot and cercospora in years with heavy disease pressure.

 

Spray soybeans between R3 and R4. R3 is when there are pods 3/16 inch long in any of the upper four nodes of the plant. R4 is when there is a pod three-quarters inch long in the upper four nodes of the plant. You typically have around 10 to 14 days to spray soybeans between R3 and R4.

 

Horlacher: This year, I’m seeing questions like this come across my desk more frequently. With economic pressures playing a larger role, “yes” is not always the immediate answer when it comes to fungicide applications. The first question I ask clients is: What is your breakeven yield for the application? This includes both the per-acre cost of spraying and the cost of the fungicide. If you’re applying the product yourself, don’t forget to factor in fuel, equipment expenses and value of your time.

 

Once breakeven yield is established, look at planting date and overall crop health. If the field was planted later — say, in late May or early June — and in poorer conditions, it may be difficult to reach breakeven. If you are looking at an earlier-planted field and good crop health, these fields often have a better chance of exceeding breakeven yields, even in the absence of significant disease pressure.

 

In tight financial years like this one, every decision should be evaluated on a field-by-field basis, rather than applying a blanket approach.

 

Mitchem: Many farmers have adopted use of foliar fungicides plus insecticides as an annual practice in soybeans. They have seen consistent returns from the practice regardless of foliar disease presence. We recognize this isn’t an Integrated Pest Management approach. However, we must recognize economic returns if they are consistent.

 

The most consistent foliar disease of soybeans is frogeye leaf spot. Typically, the farther south you are in the state, the greater the potential for impact. Frogeye leaf spot can be identified as small, light brown lesions surrounded by a darker brown halo on leaves. Your seed variety should have tolerance ratings that can help guide you on the choice to spray.

 

The most consistent timing for fungicides and insecticides in beans has been at late R2 or early R3, or at full flower to early pod development. When applied at this timing, returns of 3 to 4 bushels per acre are realistic.

 

Consider using ground sprayer widths of at least 90 feet. Smaller pull-behind sprayers track over beans too much to be consistently profitable. An alternative would be to use aerial or drone applications.