By Darren Hefty

2016 was an excellent growing season for soybeans across much of the country, but the same growing conditions that led to high yields also provided a great environment for disease development.

For any disease to thrive in your fields, it needs three factors (called the Disease Pyramid) to align.

  1. Host (Susceptible Plant)
  2. Pathogen
  3. Environment
The Disease Pyramid. Source: APS Press.

The Disease Pyramid. Source: APS Press.

If you had anthracnose, pod and stem blight, sclerotinia white mold, sudden death syndrome, charcoal root rot, brown stem rot, or any disease issue hit your crop this year there are steps you can take to reduce the chance of it happening again.  Here are two of the diseases you may not have thought much of this season that could be robbing significant yield on your farm.

Anthracnose – This is generally thought to be a late season disease since that’s when you normally notice it.  In reality, infection can occur at any point in the season.  The stress brought on by hot summer days and primarily the reproductive stages of growth lead to a weakened plant that often expresses anthracnose and other diseases.

Stems with symptoms of anthracnose stem blight. Source: APS Press.

Stems with symptoms of anthracnose stem blight.
Source: APS Press.

Pod and Stem Blight – We saw a lot of this in 2016.  You can go out right now and look at soybean residue and spot it.  Look for rows of black dots running up and down the stem.  Also, you may notice black lesions on the pods.

Pod and stems with pycnidia produced by the pod and stem blight fungus. Source: APS Press.

Pod and stems with pycnidia produced by the pod and stem blight fungus.
Source: APS Press.

Fungicide, while it may not be the total answer, is certainly a nice tool.  The key is to start early and spray late.  With many of the high-yield soybean farmers around the country, they stress continuing to spray fungicide even at R5.  For both of these diseases, that could be a key.  Since fungicide prices have crashed, it’s almost as economical now to spray twice as it was to spray once a few years ago.  If 2017 turns out to be another big disease year, fungicides will again pay big dividends.

Anthracnose and Pod & Stem Blight Summarized

Anthracnose and Pod Stem Blight Summary Table

For more information on diseases in both corn and soybeans, check out these Ag PhD apps developed in conjunction with APS Press: