The right variety can help minimize weather-related risks. Field conditions, yield potential, lodging, maturity group, herbicide program, disease and pests are all factors.
A soybean crop begins with placing seeds in soil—but how many seeds per acre and in what row width? After 15 years of replicated test plots, Farm Journal Field Agronomist Ken Ferrie thought he had the answers—and he did, for planting in the normal window.
Field value to protect. For soybean growers, getting young plants off to a fast, healthy start is a high priority. Seed treatments can help.
Choosing resistant or tolerant varieties is your first line of defense against pathogens—and an essential one. "But inbred disease resistance doesn’t really make a difference until plants reach the V1 or V2 stage," Ferrie says. "Seed treatments can help fill the gap, protecting seedlings until they reach that stage.
"With soybeans in the $12 range, every producer needs to seriously consider applying a seed treatment," he says. "Compared to $5 soybeans, you have a lot more value in your field to protect."
Still, Ferrie adds, there are no guarantees. Seed treatments don’t increase yields; they just help protect it. They provide a degree of insurance that you’ll get a healthy stand.
If there’s no threat, there will be no payoff. "Disease and insect issues revolve around the disease/insect triangle—you need a host crop, a pest and the right environment," Ferrie says. "If one element is missing, a seed treatment probably won’t earn its money back, or will return only a small portion of it. But with today’s soybean prices and the relatively low cost of seed treatments, most treatments probably will pay."
Seed treatments include fungicides, insecticides, inoculants and nematicides. "If you decide to apply one, you must select the right product for the issues you’re trying to manage," Ferrie says.
Here are some factors to consider as you make your seed treatment decisions.
Know your disease threats. Fungicide seed treatments help protect against pathogens that cause seed rot, seedling death and root rot. The infections they cause often are described as seedling blight or damping off. Pathogens that attack seedlings include Phytophthora, Pythium, Fusarium, Macrophomina and Rhizoctonia.
Phytophthora and pythium are also called water molds because they thrive in wet or saturated soils. "With these seedling blights, you will find rotted seed," Ferrie says. "It may rot even after it has already sprouted. To determine whether the problem is pythium or phytophthora, you’ll have to send the seed to a laboratory. But most seed treatment products that control pythium also control phytophthora, if they are used at the correct rates."
The other two most common seedling diseases, rhizoctonia and fusarium, occur across all moisture levels, not just in high-moisture field conditions.
"Rhizoctonia produces a distinctive brown or reddish-brown rot on the root," Ferrie continues. "The lesions will have a sunken appearance. They start at the soil line and extend below the surface."
Phytophthora, Pythium, Rhizoctonia and Fusarium pathogens reside in the soil. "Once you have them, there is no way to get rid of them," Ferrie says.
Evaluate disease risk. Launch your seed treatment strategy by analyzing the risk of disease.
"Look at the history of each field," Ferrie advises. "If certain fields, or parts of fields, have a history of root rots or seedling blights, they are prime candidates for treatment. The soil there probably tends to stay cool and wet."
- January 2011