May 21, 2019

Managing White Mold In Soybeans

Managing soil-borne pathogens can be difficult. As growers and agronomists, we may only have a few pieces of information available to work with. If we are lucky, we may have scouting records with detailed notes. In most situations, this is not the case. I am sure we all agree, our current management of soil-borne pathogens leaves room for improvement. Using Trace Genomics technology, we will help you discover the missing information. That new information is exciting, but let’s discuss how it fits into the bigger picture.

“All three factors need to come together to create the ideal conditions for infection.”

The presence of a pathogen does not mean infection and yield loss will occur. Infection and yield loss are a result of three factors: presence of the host crop, presence of the pathogen, and a conducive environment. Together, the three factors make up the Disease Triangle. Having one or even two of the factors will not lead to infection. All three factors need to come together to create the ideal conditions for infection. Let’s examine some examples to better understand the Disease Triangle.

Soybean Disease Triangle


In the figure above, are the three factors that lead to infection from White Mold (Sclerotinia sclerotiorum) in soybeans. Using the figure, let’s walk through a potential scenario. You send a soil sample to Trace Genomics and we report the presence of white mold in your soybean field. Two of the three factors are present, which could mean trouble. The missing piece of information is weather. During the late vegetative stages, pay close attention to the forecast. If the forecast is for hot and dry weather, then you may not see infection. If the forecast is for moderate and wet weather, you may want to start making plans for a preventative fungicide application. Regardless of the weather, scouting is crucial! 


Image source


In general, here are various control tactics you might consider:
  • Cultural Control: Manipulation of row spacing, plant population, planting date, crop rotation, weed control, etc. can help avoid infection from some pathogens.
  • Physical Control: Burying infected residue is often a good way to avoid potential infection.
  • Genetic Selection: Varietal resistance is often available for major damaging pathogens. Choosing the right variety and form of resistance can help.
  • Chemical Control: Seed treatments and foliar fungicides are an effective way to manage some soil borne pathogens.
  • Biological Control: The use and availability of biological product to tackle pathogens is increasing. In many cases, bacteria or fungi are used as the biological treatment.

Above is a snapshot of Trace’s Customer Portal where we surface our soil analysis. This is showing the level of Sclerotinia sclerotiorum found in soybean soil samples. Being able to measure soil-borne pathogens is the factor that we’ve been in the dark about. Guessing or working with less than adequate scouting data may be costing you time and money. Trace Genomics is here to help by providing actionable insights.


 If you are interested in biological testing, please contact us at