By Laura Lindsey, Kelley Tilmon, Andy Michel

Green stems on mature soybean plants may be the result of a source/sink problem. If there are a limited number of pods (sink), there are fewer places for the plant’s photosynthates (source) to go.

Another possible cause of stay green syndrome might be stink bug feeding. As the bugs feed, they inject saliva which may impact the plant’s physiology to remain green. To check for stink bug feeding, open a few pods and look for shriveled or flat seeds (see figure for stink bug damaged seed) that may indicate stink bug feeding. Stink bug feeding is usually heavier on the edge of the field so green plants may be more common there.