An American entomologist who conducted field trials on insecticidal seed treatments for soybeans and determined the product has little value for farmers says other researchers have reached similar conclusions.
In the Feb. 17 edition ofThe Western Producer,Palle Pedersen, a Syngenta seed treatment expert, said most research done across the U.S. Midwest has proven that insecticidal seed treatments do boost yields and provide an economic return for growers.
But according to Jonathan Lundgren, a U.S. Agricultural Research Service entomologist in Brookings, South Dakota, the majority of scientists support his contention that soybean growers are better off if they avoid insecticidal seed treatments.
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In 2009 and 2010, Lundgren held field trials in South Dakota, planting untreated soybeans along with beans treated with insecticide.
He found no difference in yield and no difference in aphid counts, between the untreated and treated seed.
“When independent researchers have addressed this question of whether insecticidal seed treatments affect soybean aphids, there are no published records of this benefitting farmers over spraying when the pest needs it,” said Lundgren in an e-mail.
One of those scientists is Matt O’Neal, an entomologist at Iowa State. In a study published in the December 2009 issue of theJournal of Economic Entomology,O’Neal and his colleagues evaluated the economic value of insecticidal seed treatment. He concluded that spraying, as needed, is a better option for growers.
“Preventative applications of insecticides, either applied to the seed or foliage, did not significantly reduce soybean exposure to soybean aphids or prevent yield lost compared with insecticides applied in an IPM approach,” O’Neal and his collaborators wrote.
“Our results are consistent with previous studies that show seed treatments do not provide significant protection against yield loss caused by soybean aphids.”
Using insecticidal seed treatment is an effective way to control bean leaf beetles, O’Neal said, which feed on the plant early in the season. But soybean aphids aren’t a problem until much later in the year. Therefore, it doesn’t make sense to apply a seed treatment a couple of months before a potential outbreak.
“There’s actually quite a few papers in the peer reviewed literature that have shown that these seed treatments will kill the aphid…. But if they don’t show up until later in the season, there really isn’t much value.”
Overall, insecticidal seed treatments are used on about 30 percent of the 82 million soybean acres in Canada and the U.S.
Farmers are using this product because they don’t have a choice, O’Neal added.
“My perception of the industry is there isn’t a lot of choice. It can be difficult for growers to get seed without treatment,” he said, noting that Syngenta has developed and sells beans with aphid resistance.
Pedersen, Syngenta’s technical manager for development of seed treatments, said that’s not the case. Growers do have the option to use insecticidal seed treatments or not.
“More than half of soybeans are treated at the local level, at the co-ops and elevators,” said Pedersen. “They don’t get forced to use it.”
Further, the price of seed is increasing and growers want to ensure that every seed counts.
“Farmers are cutting seeding rates, because seed is getting more valuable, by using the seed treatment and protecting them (seeds) from these insects and diseases. (Growers) can plant much fewer seeds and still get the same yield.”
Syngenta makes a seed treatment for soybeans called CruiserMaxx.
Ted Labun, technical manager for Syngenta Seedcare in Canada, said commercial growers in Canada have found that soybeans treated with insecticide and fungicide yielded two to four bushels per acre more than untreated seed.
But that yield boost is likely explained by the fungicide or seed genetics, Lundgren said.
“It is important for farmers to understand that these are separate seed treatments and that potential yield benefits from fungicides may be mistakenly attributed to the insecticidal seed treatment.
“I strongly advocate producers of my region to request the best genetics of beans, just hold the insecticides. Then spray if aphids exceed the threshold.”
Fungicidal seed treatment for soybeans costs around $4 per acre. Insecticidal seed treatment costs approximately $10 per acre.
