Answers are from the Indiana certified crop adviser panel: Betsy Bower, Keystone Cooperative, Lafayette, Ind.; Jeff Nagel, Keystone Cooperative, Lafayette, Ind.; and Marty Park, Gutwein Seed Service, Rensselaer, Ind..

 

I hear lots of talk about soybean cyst nematode. I have never seen symptoms. Should I pay attention to new seed treatments that claim to help or to varieties with resistance? Or should I just consider myself lucky and go on?

 

Bower: First, do some soil sampling for SCN. There are opportunities to get fields sampled for free from BASF if you are willing to share your data. In 2023, testing supported by BASF in 135 fields in southwest Indiana found that about 35% of the fields had either no SCN or levels of SCN that would not impact yield much. However, 65% of fields had medium to very high levels of SCN.

 

Pay attention to new seed treatments that control SCN or new seed traits that impart a new source of SCN resistance. There are several fields in Indiana where PI8878, the source of resistance in 90% of Indiana soybeans, is no longer working as well as it once did. SCN populations have changed in those fields. The nematodes are tolerant to the PI8878 source of resistance, and yield has begun to slip. There are a few companies incorporating Peking resistance into some of their beans, and there are new tools being developed to reduce the negative impact of SCN.

 

Soon, there will be a new source of SCN resistance bred into soybeans from BASF, and Syngenta has a new seed treatment coming geared toward reducing SCN and root knot nematodes. FMC has a biological seed treatment called Avodigen that is being used in addition to SCN resistance as another tool for SCN.

 

Nagel: Almost every soybean field has some level of SCN. Yield loss can be significant, even without visual symptoms. Yield impact is often more severe on sandier soils. Often, SCN goes unnoticed on heavier soils until they build to levels where visual stunting or noticeable yield loss occurs.

 

If you have never sampled for SCN, sample for detection and level of SCN egg counts. The level of SCN will direct the crop rotation and source of SCN resistance in soybeans. For decades, the main source of SCN resistance used in breeding programs has been PI88788. There are now some commercial soybean varieties that have Peking as the resistance source, and they yield better in the presence of SCN. It will be important to rotate resistance sources.

 

Seed treatments such as Saltro and ILevo can be used in combination with SCN-resistant varieties. These can help mitigate yield loss, but you still will have SCN. There are some newer seed treatments in development, but they are not available yet. Trials with biologicals that claim activity on SCN and some other nematodes show inconsistent results.

 

Park: Northwest Indiana is known for cyst pressure, especially on sandier soils. But not every area has high levels. Even if you have not seen damage from cysts, it is important to still evaluate pressure. Dig plants in June and July and evaluate roots for cysts. Focus on lower organic matter soils or areas that have not been yielding well.

 

Another option is to pull some soil samples and send them to a reputable lab for evaluation. Once you see results, then you can make your plan.