Under normal planting conditions and soil temperatures soybean seedlings should emerge five to nine days following planting. This year many acres were planted in early May, creating some concern because cool soil temperatures will slow down germination and emergence allowing diseases and insects more time to harm seed and reduce stand. Early planted soybeans without a fungicide seed treatment are more vulnerable to fungi like Pythium which thrives in cool wet soils. Once soil temperatures warm up, other diseases like Phytophthora root rot and Rhizoctonia can reduce soybean stand. It is critical to evaluate soybean fields after emergence and determine what kind of stand you have.

The good news is soybean is a very forgiving crop and has a great capacity to compensate for reductions in stand. University of Minnesota research on stand reduction suggests that substantial reduction in plant stands has little effect on yield (figure 1).

It takes a 50% stand reduction to reduce potential yield by 10%.Evaluate stands closely before deciding to replant, also considering the calendar date. Weigh yield loss because of stand reduction against the penalty for delayed planting University of Minnesota research on planting date suggests that substantial yield reduction does not occur until after June 1 (figure 2). The early planting this year may lead to earlier opportunity to replant, meaning less yield loss from re-planting date.