Top 7 Soybean Diseases of 2022

Which diseases infected your soybean crop this season? 

All growers struggle with diseases and each season must consider the best way to prevent infection and treat their soybeans when the inevitable occurs. In 2021, in the US, 5.8% of potential soybean yield was lost due to diseases. 

Taranis helps ag advisors & growers conduct soybean scouting and detect diseases early and accurately using digital crop intelligence tools. We have analyzed our dataset of leaf-evel insights from 2022 and have compiled a list of the most prevalent soybean diseases to infect crops across the US. 

The top seven diseases were all fungal diseases; the main offenders being Brown Stem Rot, Brown Spot, and Downy Mildew. 

In this blog we will share the top diseases we found, based on crop imagery from millions of acres across the US Midwest, as well as their geographic location. Offending pathogens can potentially spread through wind, soil, equipment, seeds, and water, and knowing the location of the disease incidents can help you plan for next season and be on the lookout for potential new infection sources. For local information about diseases that impacted your region this year, contact Taranis.

Major Soybean Diseases of 2022

1. Brown Stem Rot (BSR)
   Brown Stem Rot is caused by the fungus Phialophora (or Cadophora) gregata, and symptoms of this disease occur early in the season but the damage appears in the summer. If not detected properly, it can be confused with Sudden Death Syndrome. When severe, yield losses could be up to 40%.We found BSR across the Midwest, towards the South and in the East as well. The states suffering from BSR the most were Indiana, Ohio, Missouri, Illinois, and Michigan.
   
2. Brown Spot (aka Septoria Brown Spot of Soybean)
   Brown Spot is a foliar disease caused by the fungus Septoria glycines. It is a common soybean disease but does not always cause serious damage. Brown Spot can result in yield loss in some situations (~2 to 4 bu). Continuous soybean will increase the severity of the disease and it is more likely to develop in warm and wet weather.We found Brown Spot all over the Midwest and South, most commonly in Ohio followed by Indiana, Missouri, Kansas, Illinois, Michigan, Kentucky, and Nebraska.
3. Downy Mildew
   Downy Mildew is a common foliar fungal disease, caused by the pathogen Peronospora manshurica. This disease has a low impact on yield loss. Downy Mildew occurs when humidity levels are high.In 2022 it appeared throughout the Midwest and South, most prominently in Indiana, Ohio, Illinois, Missouri, Iowa, and Kentucky.
   
4. Alternaria Leaf Spot of Soybean
   Alternaria Leaf Spot is a fungal foliar disease that usually appears late in the season and does not cause significant damage. The seed-borne pathogen attacks the pod where there are cracks in the pod walls. Alternaria is common in Brassica crops.The states with the most instances of Alternaria Leaf Spot were Ohio, Illinois, Missouri, Maryland, Indiana, Delaware, Kansas, Arkansas, and Mississippi.
   
5. Sudden Death Syndrome (SDS)
   Sudden Death Syndrome is caused by a soil-borne fungal pathogen named Fusarium virguliforme. The pathogen remains in the soil, can survive freezing temperatures, and infects the young plants in the spring, moving from the roots to the leaves. SDS can cause serious damage to yield and its instances are closely correlated with Soybean Cyst Nematode (SCN).Scouting for SDS can be challenging because it resembles other diseases, such as Brown Stem Rot.We found the most cases of SDS in Indiana, Missouri, Ohio, Michigan, Illinois, Maryland, and Wisconsin.
   
6. Powdery Mildew
   Powdery Mildew is a foliar disease caused by the fungus Erysiphe diffusa. It requires cool cloudy weather and low humidity to develop. Powdery Mildew is not common in the Midwest however we found a few instances in Missouri and Indiana. The disease usually appears late in the season and does not often cause yield loss.
   
7. Frogeye Leaf Spot
   Frogeye Leaf Spot is a disease caused by the fungus Cercospora sojina that appears on leaves as grayish spots surrounded by a reddish ring border. Frogeye Leaf Spot is a significant soybean disease in the South and its relevance is increasing in the North as well. The degree in which the disease negatively impacts yields varies and if severe can be up to 35%.It favors warm, wet, and humid weather.Our data showed infection from Mississippi northwards to Tennessee, Kentucky, and ending in Ohio.
   

The Importance of Early Detection and Continuous Monitoring of Soybean Diseases

During the growing cycle, disease scouting is critical to maintaining healthy crops and decreasing the spread of diseases. Early and effective scouting can prevent yield loss and save expenses on fungicide application. Continuous monitoring is also important to stay on top of the diseases developing and know when to precisely apply chemicals on the area of concern. 

Recent advances in technology, such as accurate leaf-level insights, has improved the precision of disease scouting and identification. Having precise data allows you to stay on top of the soybean diseases developing on your farm. Monitoring diseases in your state and region gives you an indication of what potential pathogens to be on the lookout for, which is critical to prevent yield loss and unnecessary fungicide applications. 

For more information about soybean diseases this year, contact Taranis.