There were multiple reports of Sudden Death Syndrome (SDS) in soybeans this past year. The cooler, wet season helped promote the disease in susceptible varieties, but the presence of soybean cyst nematode (SCN) can also increase the effect of SDS.
More information on SDS can be found in the article posted earlier this year: Sudden Death Syndrome in Soybeans. One management option is to plant a resistant to moderately resistant variety. For information on soybean variety disease ratings and sampling for nematodes, visit UTcrops.com. The combination of the fungus that causes SDS (Fusarium solani f. sp. glycines) and SCN will have a greater effect on yield on a variety that is susceptible to both pathogens than either pathogen would on its own. Both pathogens are present in Tennessee, so I recommend sampling for SCN. The best time to sample for SCN is in the fall (now), when the population is the highest.