Heavy rain events throughout the summer set many soybean fields up for sudden death syndrome (SDS). In fact, conditions were so prime for SDS that Michael McCarville, seed growth technical service rep for Bayer, says foliar symptoms appeared two weeks earlier than normal this season across the two states hit hardest: Iowa and Illinois. Unfortunately, symptoms that appear earlier in the season tend to lead to heavier yield loss, he explains, due to pod abortion and shrunken seeds.

Looking back at the past few years of SDS pressure, McCarville says 2010 was the worst year for SDS, 2014 was bad and 2015 was regionalized. “This year is giving 2010 a run for its money,” he says.

PROPER ID: Suzanne Bissonnette, assistant dean of agriculture and natural resources, University of Illinois Extension, says several of the samples sent in for sudden death syndrome testing were actually brown stem rot.

As farmers wrap up the 2016 harvest and make plans for 2017, here’s a look at five reasons why SDS is such a difficult disease to manage, and what can be done to reduce infection next year:

1. Mistaken identity. Was it SDS? Or was it brown stem rot? Suzanne Bissonnette, assistant dean of agriculture and natural resources, University of Illinois Extension, says several of the samples sent in for SDS testing were actually brown stem rot. Bissonnette says the only way to identify SDS versus brown stem rot is to split open the stem and see if the tissue is white or brown. White tissue indicates SDS.

2. Rotation doesn’t help. McCarville says rotating to corn won’t help suppress SDS. The pathogens that cause SDS can reproduce and sustain themselves on corn. In fact, McCarville says, one of the worst SDS fields he saw this season was coming off six years of corn.

SCN CONNECTION: SDS is not contingent upon soybean cyst nematode, explains Michael McCarville, seed growth technical service rep for Bayer, “but it’s definitely worse off.”

3. Tolerant varieties may not be enough. Selecting varieties rated highly for SDS tolerance is a good place to start. However, McCarville says those varieties are rated based on foliar symptoms, not the root rot phase. “There’s actually very little variation in commercial varieties between how susceptible they are to SDS,” he explains. “The SDS-tolerant trait is present in about 95% of commercial varieties.” Relying on one trait is never a smart choice, McCarville adds.

4. The soybean cyst nematode connection. Soybean cyst nematodes (SCN) lurk in about 75% of fields across Iowa and Illinois, according to McCarville, and they are the No. 1 cause for yield loss. SDS tends to be more prevalent in fields with high SCN levels. In other words, McCarville explains, SDS is not contingent upon soybean cyst nematode, “but it’s definitely worse off.”

5. There is no cure. We don’t know what Mother Nature will throw at farmers next season. What we do know, McCarville says, is that the pathogen that causes SDS is hiding in fields. One way to prevent significant infestations next season is to plant soybean varieties treated with a seed treatment such as ILeVO. ILeVO paired with Poncho addresses both SCN and SDS.

McCarville says harvest is a great time to note fields with SDS for next season, and to take soil samples to determine SCN populations.