David Moseley and Stephen Ippolito, LSU AgCenter Scientists

There have been several cases of green stem reported in mature (R8) soybean fields. A Science for Success factsheet (Understanding Green Stem in Soybeans) explains that green stem is a disorder where the stems of a soybean plant stay green after the pods have fully matured. The exact cause of green stem is unknown. However, it is generally associated with any factor that reduces pod and seed development. This is because the developing seeds are the "sinks" that draw nutrients from the plant's "sources" like the leaves and stems. When the seed production is reduced, nutrients can be retained in the stems and the stems can remain green. One of the commonly associated factors is environmental stress, which can lead to premature loss of pods and seeds. Generally, green stem does not appear to limit yield however it can severely reduce harvest efficiency. The green stems can clog or choke harvesting equipment. Operators may need to decrease combine speed if there are too many green stems. However, in some cases it has been observed where environmental stresses have seemed to cause green stem and a severe loss of yield.

Additional information can be found in this Crop, Forage, & Turfgrass Management article. A self-study CEU is available from Crops & Soils magazine where CCAs can earn credit on green stem if they read the Crop, Forage, & Turfgrass Management diagnostic guide and answer the quiz questions found at this Crops & Soils magazine link.

Figure 1. Leaves remaining on mature soybean plants after applying a harvest aid.

Figure 2. Soybean stems remain green after the pods have matured.

Figure 3. Green pods and stems can cause issues in harvesting.

Figure 4. Variety differences in green stem were observed on a farm.

Figure 5. Soybean plants that have been at the R8 growth stage for several weeks, but their stems and branches have remained green. In addition, although there are several pods per plant, the seed count per pod is very low.