Michael Stout, Blanchard, Tobie M.
Rice growers soon will have one less weapon in their arsenal to fight the rice water weevil.
After this year, the international company Bayer CropScience will no longer manufacture the seed treatment Icon for rice grown in the United States.
"The reason the company cited was declining sales," said Dr. Michael Stout, an entomologist with the LSU AgCenter. "It was no longer profitable for them to sell Icon in the United States."
The insecticide Icon was introduced in 1998. Rice farmers in Louisiana found it very convenient to use. They could treat their seeds with Icon before planting and not worry about subsequent treatments or accurate timing of insecticides after planting, experts explained.
Another benefit was that Icon was very effective against a major pest of rice – the rice water weevil.
"Based on the work that I do with experimental plots, I would place yield loss due to the rice water weevil at 10 percent or more," said Stout. "It’s a significant strain on rice yields in Louisiana."
Icon works by coating the roots of the rice plant as it grows. Then the rice water weevil attempts to feed on the treated roots and dies.
Many rice farmers in Louisiana began using Icon in the late 1990s. But use has declined in recent years as farmers became more comfortable with less expensive treatments. Icon could cost around $13-$15 per acre for seed treatment.
Another reason for the decline was growing concern about a potential side effect of the pesticide.
"Farmers were a little bit nervous about a possible link between the use of Ion and crawfish mortality," Stout explained.
In South Louisiana, a lot of farmers grow crawfish in the same fields where they grow rice. LSU AgCenter researchers have said using water in crawfish ponds that was just drained from newly planted rice fields with Icon-treated seed could kill some crawfish.
Stout says he is testing new products to fight the rice water weevil. One product is a seed treatment that would be similar to Icon.
"Right now there really are no products that are similar to Icon in the terms of being seed treatments," Stout said. "The alternative products are all products that are applied after flooding a field."
Products such as Karate and Mustang Max are more difficult to use than Icon, according to Stout. These two pesticides have a similar chemical composition, and Stout said he is concerned the rice water weevil could develop a resistance to them.
Farmers still can use Icon and any remaining supplies through 2006. A press release from Bayer CropScience says, "Icon remains a leading rice seed treatment globally."
The company will continue to market Icon in foreign rice-growing regions.