With wet field conditions during spring planting or fall harvest season, like the tri-state region saw in 2019, the equipment and trucks that enter each field are more likely to carry soil from field to field. Mud on the wheels or tracks of equipment, soil collected on flat surfaces of equipment, and even mud on the boots of someone walking in a field are all ways soybean cyst nematode (SCN) can be moved from an infested field to an otherwise clean field.
Flooding and movement of soil or water will move nematodes, and soybean cyst nematodes are the most devastating and yield-limiting pest of soybeans in the United States. A recent three-year study from the SCN Coalition conducted in the U.S. estimated that soybean cyst nematode (Heterodera glycines) caused annual losses of $1.286 billion (128.6 million bushels) for U.S. growers.
Wet field conditions can create an urgency for growers to plant or harvest their fields during smaller windows of opportunity. This often precludes sanitizing equipment to prevent soil transfer between fields as well. The result can be a higher incidence of moving soybean cyst nematode-infested soil between fields as well as across individual fields when compared to drier field conditions.
Soybean cyst nematode levels can vary greatly from site to site and season to season. The best way to manage them is to never let them into your fields. If you believe you don’t have soybean cyst nematodes in your fields, soil testing is still a good way to confirm your suspicions.
If you do have soybean cyst nematodes in your fields, limiting their spread and minimizing their movement is still important. Continued soil testing to monitor their levels, using soybean cyst nematode-resistant soybean varieties and possibly utilizing some of the available seed coatings, and rotating to non-host crops like corn and wheat can help protect your soybean yields in the future.