Icon, a seed treatment applied for the control of rice water weevil and grape colaspis in rice, is being voluntarily removed from the market, according to entomologists.
“There isn't any Environmental Protection Agency pressure; the company just decided to remove it,” said John Bernhardt, University of Arkansas rice entomologist. “It's very disturbing because we're left with no pesticide option to control grape colaspis.
Icon, a pesticide containing the active ingredient fipronil, was introduced by Rhone-Poulenc Ag Products in 1998. Rhone-Poulenc later merged with AgrEvo to form Aventis CropScience, which was acquired by Bayer CropScience in 2002. Bayer subsequently sold the fipronil active ingredient to BASF Corp.
“Icon is part of a novel class of insecticides discovered a few years ago,” said Bernhardt, a researcher at the Rice Research and Extension Center in Stuttgart, Ark. “This class has a broad range of activities, and the product is registered for use in a few crops as well as other uses (like flea control on pets). It was tested in rice as a control, mainly, for the rice water weevil. The weevil is our second-most bothersome pest in the state (with the rice stink bug being first), and Icon was registered for its control. It works very well.”
After Icon was registered for water weevils, Bernhardt and colleagues wondered if it had any activity against grape colaspis, commonly called the lespedeza worm. Normally a minor pest, grape colaspis can wreak havoc on a rice stand under certain environmental conditions.
“When we finally got some field data showing colaspis is controlled very well by Icon, it was put on the rice label,” says Bernhardt. “When talking about this product at grower meetings, we said, ‘This is an interesting pesticide. You can put it on as a seed treatment. It will suppress chinch bugs; it will control grape colaspis, water weevils, and a couple of minor pests.’ It was (and is) the only pesticide registered for grape colaspis control.”
Cultural practices to control grape colaspis include flooding the field once infestation is realized. Or, if a farm has a historical problem with colaspis, changes in tillage practices can help (problem fields are usually composed of silt loams). Neither option is, in most cases, as economical as an Icon treatment nor as effective, says Bernhardt.
With news of Icon's loss to growers, Bernhardt began investigating other products that could help fill the void.
“There are products registered for other crops that have colaspis activity. We're going to see if they help in rice. Plus, we're going to investigate products already registered in rice. Maybe we can find something.”
This is a “strange” situation, says Bernhardt. Even with farmers asking to buy it, the uses for Icon are limited given the small amount of acreage planted to rice in the United States. For a company to invest enough money to register a product in rice, a certain amount of return must be promised. Not many companies consider rice a big enough crop to expend funds.
“We can often find products useful for rice,” says Bernhardt. “But getting the companies to register them is very difficult. It's just cost-prohibitive.”
But producers need Icon, he says. Some years, a producer will lose only 2 percent of his stand to colaspis and won't even know the pest is there. Other years, like in 2001, “we'll have growers lose 100 percent of their stands.”
“Usually, damage is sporadic in a field — but that isn't always the case,” says Bernhardt. “A farmer can be faced with replanting and, if he's already pulled levees, he's got added problems.”
Grape colaspis in rice normally follows a soybean rotation. In rare cases, infestation will follow a corn rotation. At least two generations of the pest occur annually in most soybean fields. That's particularly true in fields where later maturity groups are planted.
Following soybean harvest, the immature form of the pest — many people call them white grubs, although they're not — burrow deep into the soil below the freeze line. In the spring, the larvae move closer to the soil surface to feed on crops and mature.
“Icon is pretty expensive when compared to herbicides running $4 per acre,” says Bernhardt. “Icon costs, at the lowest effective rate (0.5 ounce per acre applied as a seed treatment), around $10 per acre. A 0.75-ounce rate — which will run a grower between $13 and $15 per acre — is the lowest rate we recommend for rice water weevil control.”
After 2004, no more Icon will be manufactured for rice. Any remaining supplies can be utilized through 2006.
Bernhardt says producers he's spoken to about Icon's departure are surprised.
“They all want to know, ‘What will we do?’ That's a great question. Last year, about 30 percent of Arkansas' rice acres (close to 500,000 acres) had Icon on it. Principally, that was for grape colaspis control. I think just now many producers are finding out about the product. And just as they find out, we're to lose it. Icon is important.”
After farmers began using the product, Bernhardt says, they've facetiously reported back that, “‘Icon cured my salt problem. I now have a good stand of rice.’ All along, their poor stands were attributed to salt, poor seed, germination problems and disease. They didn't realize that grape colaspis was causing the problems.”