Fall is in the air and harvest is starting up across Iowa. It has been noted soybean are holding onto their leaves. This green bean effect is more often thought of as green stems, however, this year there are more leaves and petioles staying green and attached to the main stem. Take note this occurrence may mean that soybean grain is drier than expected based on plant appearance. This green bean effect can be caused by both biotic (stink bugs, thrips, viruses, etc.) and abiotic (weather, late planting, fungicides, etc.).
Management to avoid green bean syndrome is difficult in-season because of variety of causes. At harvest, the best solution to green bean syndrome is to harvest fields when the soybean seeds are at the proper moisture content. Make sure the sickle bar on the combine is sharp and well-maintained. Slower harvest speeds will be needed to account for more soybean biomass coming through the combine.
Soybean at harvestable grain moisture with green (and yellow) leaves still attached. (photo credit: Rebecca Vittetoe)