If you're waiting for Asian soybean rust to appear in your fields before you spray, Marty Wiglesworth suggests you reconsider.
“I’m really trying to steer people away from waiting until they see rust in their fields, because according to the research we’ve got, it’s difficult to make up the yield you’ve lost by then,” says Wiglesworth, a plant pathologist and technical brand manager of fungicides for Syngenta Crop Protection in Greensboro, N.C.
Asian rust can hit a healthy soybean field and completely defoliate it in 4 to 5 weeks, he says, so no-tillers should review the available fungicides and take action before the problem arrives.
Although no fungicide currently available or being developed will completely control or eliminate soybean rust, he says, three different classes of fungicides can be used to manage the disease and protect yields:
The triazole-based products are considered “curative” because they can be applied to an infected plant to stop the creation of additional spores. Triazole-based fungicides include products such as Volacure, Alto, Tilt, Laredo and Delmark. “They do a great job,” Wiglesworth says, “but there are always escapes, and those escapes can worry you.”
Strobilurin-based compounds are called preventative because they act to prevent the disease. Spores are controlled when they land on treated leaves and take up the compound, Wiglesworth says. “If the spore gets into the leaf, the strobilian chemistry has very limited effect,” he adds.
The strongest control is achieved by combining triazole and strobilurin products to complement one another…