Sudden death syndrome and soybean cyst nematode are among the top yield-robbing soybean pests for U.S. growers. SDS infection can cause an annual loss of 25 million bushels, and SCN also steals yield each year. When the two pests are found together, the risk for yield loss is even greater.
“SDS and nematodes have a hand-in-hand relationship,” says Dale Ireland, Syngenta seed care technical product lead. “In the worst cases of SDS, there’s usually a nematode involved, and its typically SCN in the U.S. soybean belt.”
As nematodes feed on young soybean roots, they open holes within the roots and create a higher risk of Fusarium virguliforme infection — the cause of SDS. The SCN parasite also stresses the plant and weakens its defenses, making the plant even more vulnerable to SDS.
While not every field that has SDS also has SCN or vice versa, when the two do occur in the same field, SDS symptoms appear earlier and are more severe. “The earlier SDS symptoms appear in the leaf canopy, the more yield will be lost as the plant’s ability to photosynthesize is decreased,” Ireland says. “That’s why it’s crucial to have a management plan for both SDS and SCN to give soybeans the best protection. It’s vital to get a strong start and a strong finish for beans.”
As farmers begin thinking ahead to the 2020 growing season, Ireland suggests tactics to consider for stopping these partners in yield theft:
Know your numbers. Best time for growers to sample soil for SCN is postharvest because nematode populations will be at their peak before fields begin to freeze. Soil sampling in winter can be difficult, and waiting until spring won’t leave much time to implement an effective SCN management plan.
Consider crop rotation. Rotating infested crops with a non-host crop will help disrupt SCN’s lifecycle, but studies haven’t shown crop rotation to manage SDS. The Crop Protection Network, which includes Iowa State University Extension, says corn crop residue and soil can harbor the SDS pathogen. While this practice can help prevent SCN from becoming a larger issue, additional tactics are needed to manage both pests.
Plant SCN- and SDS-resistant varieties. Since SDS and SCN both attack and infect soybeans soon after planting, variety selection with SDS and SCN genetic resistance is crucial to protecting yield potential. However, soybean variety selection can’t be the only management technique, as SCN is becoming increasingly less susceptible to the most common source of resistance in bean varieties due to overuse. That’s why growers should supplement their genetics with a powerful seed treatment with activity on SDS and SCN.
Choose an upgraded seed treatment. In 2019, Syngenta’s latest fungicide seed treatment, a product named Saltro, received federal registration. Saltro provides protection against SDS, as well as several nematode species including SCN.
COMPARISON: Saltro treated beans on the left are healthy, while untreated beans on the right are infected with SCN and SDS.
“With more power than older SDS seed treatments, Saltro offers superior SDS protection and dependable nematode activity,” says Ireland. “It does it all without causing any early-season plant stress response or phytotoxic effects. Upgraded SDS protection plus nematode activity and no stress means Saltro will help soybeans reach their full genetic yield potential. Saltro takes soybean protection to the next level.”
For more information, visit Syngenta.