Reports of green stem disorder sightings in Missouri have picked up as harvest wraps up.

Green stem is present when stems that should otherwise be brittle and brown at the end of a growing season remain moist and green. According to the University of Illinois Extension, while pods mature and soybeans become ready for harvest, these green stems will not reach the same point of maturity. Green stem also makes it difficult to harvest soybeans in a timely manner. If mature seeds are left in the field, seed quality can decline and result in an unsellable product within just a few weeks.

A disease that affects all soybean growing regions, green stem disorder is exceedingly difficult for growers to predict. According to the Iowa State University Extension, the cause of green stem disorder is unknown and might be due to a combination of factors, including:

• Disease infection
• Insect damage
• Lower fall humidity levels and higher fall temperatures
• Soil moisture stress

As researchers continue to work to diagnose the cause of green stem, the disorder is sometimes misdiagnosed as the strobilurin-greening effect brought on by the use of fungicides.

Green stem disorder and the strobilurin-greening effect have drastically different effects on soybean yields. While green stem disorder can negatively impact soybean harvests, the strobilurin-greening effect extends the window for photosynthesis and can help plants produce larger beans, fuller pods and improve soybean retention. This benefit comes with using a fungicide containing strobilurin, such as Trivapro^® fungicide.

Unfortunately, once green stem is found in a field, there is little that growers can do to mitigate its effects. But researchers continue to study this elusive disease and search for a treatment.

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