The latest on SCN risk to soybean growers and best practices to manage the pest
Soybean cyst nematode (SCN) is not a new issue for growers, but how to manage it effectively is a new conversation. A serious threat to soybean production across the U.S., SCN populations can exponentially grow to wreak havoc on yields in just one year if not controlled properly.
Untreated SCN can also combine with other soil-borne pathogens to cause additional damage to yield by:
- Stunting roots
- Increasing susceptibility to brown stem rot and sudden death syndrome
- Reducing effectiveness of nitrogen fixation
- Disrupting vascular function
But what is proper management? According to Dair McDuffee, Valent U.S.A. Seed Treatment Specialist, the basics for SCN management will never change. “Proper management starts with the varietal selection, cultural practices and seed treatments for enhancing your protection.” How can growers give these steps some new consideration?
Varietal Selection and Genetic Components
Step one for any season-long management approach to SCN is seed selection.
The most common way to manage SCN in soybeans is through a gene called PI 88788. McDuffee says that SCN are recently starting to adapt and are gaining the ability to reproduce on soybeans with that gene. “It has worked well for so long but as resistance continues, growers need to be prepared.”
To combat these resistance issues, McDuffee suggests an integrated pest management (IPM) strategy to SCN. “Active management is going to be the difference in preventing and controlling SCN,” he adds.
Practices for Protection
Once a field is infested with SCN, it is impossible to eliminate. However, the pest can be managed using some of these tips.
The most important time of year to act for SCN is in the fall. McDuffee suggests performing field tests in the fields you will be planting into next year to know where you stand with pest pressure.
After the season, McDuffee suggests practices like rotating resistant varieties, rotating to non-host crops and properly managing host-weed species can help to slow population build-up within an infected field. Cleaning implements between fields can prevent the spread of the pathogen to fields that are not yet infected.
As for in-season management, McDuffee says that is tougher.
“The damage rarely shows during the season. You can have two fields look exactly the same, but one can yield anywhere from 5 to 20 percent less if it has a large and active nematode population,” McDuffee says. “Since there are no obvious signs of infestation, growers may not be aware of the damage and that is why it is important to scout for the disease throughout the season.” Stunting, yellowing and early crop maturation are all symptoms of SCN, but are often mistaken for other causes.
Using multiple modes of action early on for control will extend the life of SCN technologies under threat from resistance.
“In almost all cases of resistance, bringing in multiple modes of action early can extend the life of those technologies under threat,” says McDuffee. “Until more progress is made, PI88788 is our best defense against SCN and better overall management is key to keep it working harder and longer in your field.”
One way to do this is with seed treatments. Products like Aveo® EZ nematicide from Valent U.S.A. can help growers with that next step to manage SCN through IPM. Aveo EZ is a stand-alone biological seed treatment that colonizes the root and grows with the plant from the start of for season-long protection.
Taking another look at SCN management and current plans can help growers continue to fight resistance issues and keep fields clean. For more information on creating an integrated plan for SCN, visit thescncoalition.com.