Green Stem Syndrome

Every few years this phenomenon becomes a hot discussion topic. This year, as we are in the middle of soybean harvest in certain areas, it is of interest again.

What causes green stem syndrome?

There are several possibilities, and each can be caused by different agents. This year’s incidents seems to be related to environmental conditions. Potential causes are mutated plants, environmental conditions, viruses, and insect feeding. Currently, there is still a bit of uncertainty as to the exact cause.

• It was originally thought that diseases such as pod mottle virus vectored by feeding from aphids or stink bugs could cause this issue.
• Then there is the mutated or rogue plant theory producing green stems, but only on a very few scattered plants. They have very few pods and very few beans per pod. Again, this will not be on a field wide basis, but rather only a few scattered plants.
• Some Universities have data to prove that the virus theory may not be the case either.
• Then we get to the environmental conditions. Given this growing season, this is most likely the case.  If soybean pod set was less than we had plant resources for, and then we had great or very good conditions late season, we can get green stems.  Basically, we have excess plant resources, and the plant stays green longer. Many agronomists refer to this as “sink and source.” We have more “sources” (plant sugars etc.) than we have a “sink” (soybeans) for them to go. One observation to support this was where one row had a limited population from a planter issue. Plants with less interplant competition stayed greener for a greater period of time.
• Late planting and/or emergence
• Late herbicide application
• Fungicide application
• Research at the University of Illinois demonstrated that the use of Group 11 strobilurin fungicides (QoI), particularly pyraclostrobin, resulted in a higher incidence of green stem.

Brian Weller
Western Region
507.456.3034

Rod Moran
Western Region
507.456.3034

Dan Ritter
Central Region
219.863.0583

Branden Furseth
Northern Region
608.513.4265

Mark Gibson
Eastern Region
260.330.8968

Amanda Goffnett
Eastern Region
989.400.3793

Ryan Mueller
Eastern Region
989.400.3793

Enjoying our Agronomy Updates? Suggestions for topics you'd like us to weigh in on? Drop us an email at dairylandseed@dairylandseed.com. We'd love to hear from you!