What Fungicide or Product Should I use to Manage White Mold and how Should I Apply it?

Figure: White mold fungicide efficacy trial conducted in 2020. Red bars are yield and blue bars are white mold disease severity index.

Each year we conduct white mold fungicide efficacy trials. We examine old and new fungicide products, fungicide timing and application techniques. The two following graphs are snapshots from individual trials conducted over the last two years at the MSU Montcalm research station. We conducted these trials in 15” rows at a population of approximately 160,000 plants per acre, in irrigated fields with a history of white mold. The soybean variety used was moderately susceptible to white mold.

Note, the amount of white mold that developed in the trial is expressed as the disease severity index (disease severity x disease incidence) and is shown in blue, while the respective yield (bu/A) of each treatment is shown in red. Disease severity index or yield that is different between treatments is indicated with different letters. Also take note of the different application timings that are indicated such as R1 (beginning of flowering – plants have at least one flower on any node), R2 (full flowering - there is an open flower at one of the two uppermost nodes), and R3 (beginning pod - pods are 3/16 inch at one of the four uppermost nodes).

In addition to conducting these trials, we also collaborate with colleagues in states across the north central region allowing us to collect data on product performance over multiple environments. The fungicide efficacy table is a consensus of product performance for white mold and other soybean diseases and can be found here:
https://cropprotectionnetwork.org/publications/fungicide-efficacy-for-control-of-soybean-foliar-diseases
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In addition to making the decision of what to apply, the “how” of fungicide application is also very important. For ground rig applications the following considerations should be made

• Apply 15 to 20 gallons of water per acre 
• Adjust nozzle pressure to around 40 psi 
• Maintain ground speed at 10 mph or less 
• Utilize nozzles that produce a single flat fan spray pattern directed straight down into the canopy
• Select nozzles that generate fine to medium droplets
• Use the mid-point in the crop canopy as your target and adjust the boom height from this point

 
A helpful article discussing these points in more detail can be found here: https://www.canr.msu.edu/news/equipping_and_operating_sprayers_to_control_insects_and_diseases_in_soybean

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Figure: White mold fungicide efficacy trial conducted in 2021. Red bars are yield and blue bars are white mold disease severity index.