We’ve received a few pictures from around the state of green soybean pods splitting and also seed sprouting out of pods. While it is not uncommon to see pre-harvest pod shatter just prior to harvest due to re-wetting of dry pods, the pictures we’ve received have been of soybeans at the R6 growth stage.
Splitting of green pods may be related to the recent warm, wet (high intensity rainfall), and humid weather. (The Western Agricultural Research Station in Clark County had a high temperature of ≥93°F over a three day period in September followed by 3.5 inches of rain in a four day period.) Wet conditions at the R6 growth stage results in a large seed size that may split pods. Once the soybean pod is open, the seed is susceptible to pre-harvest sprout (germination of seed in the pod prior to harvest). Researchers have found differences in pre-harvest sprout among soybean cultivars.
Another (potential) cause of pre-harvest sprout is insect feeding. Feeding may open the pod where moisture can enter and sprout the seed.
Dougherty, R.W., and H.R. Boerma. 1984. Genotypic variation for resistance to preharvest sprouting in soybean. Crop Sci. 24:683-686.
Holshouser, D. 2015. Wet conditions may lead to soybean seed sprouting. Virginia Ag Pest and Crop Advisory. Available at: https://blogs.ext.vt.edu/ag-pest-advisory/wet-conditions-may-lead-to-soy...