Sudden death syndrome (SDS), caused by a fusarium species in soil, needs cool and moist conditions to thrive. It also needs an entry point, and soybean cyst nematodes (SCN) make those for the pathogen in roots of soybean when they attack the crop.
Effectively managing SCN, therefore, is just one part of the puzzle in managing SDS — but that battle also requires the use of resistant genetics and effective seed treatments.
“When you look at the symptoms of SDS, there are two different kinds of symptoms, above-ground and below-ground,” says Abhi Deora, seedcare technical lead with Syngenta. The above-ground symptoms have three different phases: the first is yellowing of leaves or intra-veinal yellowing, which eventually merges together, making the whole leaf yellow. The second phase is yellow areas turning brown and the leaf dying. The third phase is premature defoliation, as infected plants will drop leaves and the plant will shut down.
Yield loss to SDS depends on several different factors says Deora. The first is disease pressure in your field, and the second is the genetic tolerance of the variety in your field. If you have a tolerant variety, you’re going to see less impact on yield, he says. The third factor is the timing of symptom development, which can be critical to how your crop pulls through.
“If you have the symptoms already appearing right up to the reproductive stage, flowering stage, or symptoms are appearing at pod-fill stage, you’re going to have more impact,” says Deora. There may be flower or pod abortion at this stage. If symptoms appear later, there may be an impact on seed size and weight. Furthermore, if you have SCN in the background, and a susceptible variety, the damage is much worse.
So how do you control SDS? Choosing a tolerant variety is the first tool to use when managing SDS, but it’s not a silver bullet, says Deora. Even with a tolerant variety, there’s still a yield loss but symptoms will be less than what you’d see on a susceptible variety. Seed treatments are also very effective in combination with a tolerant variety, because they can control early infection which can delay or suppress symptoms later on.
If you can combine the right variety with a seed treatment, you’re creating a knock-out combination for SDS.
Watch the full video to hear Deora talk about a new seed treatment product from Syngenta