WASHINGTON, D.C. — The U.S. EPA has given final approval to a new pesticide designed to eradicate nematodes called fluensulfone. People in the industry have been searching for effective and affordable alternatives to methyl bromide for years.
Methyl bromide, a longstanding soil fumigant, has been largely phased out by the EPA because of an international treaty, the Montreal Protocol. Environmentalists inspired the treaty over their concerns that certain chemicals were depleting the ozone layer of the Earth’s atmosphere.
Agricultural interests have chafed over the disappearance of methyl bromide, because it’s an inexpensive and effective treatment for nematode pests. Iodomethane, also known as methyl iodide, was marketed as a replacement for methyl bromide under the brand name Midas.
Its manufacturer, Arysta LifeScience North America, voluntarily cancelled its U.S. registration in 2012. Environmentalists had a problem with that product as well, but an Arysta spokeswoman said Midas was discontinued for business reasons. It is still being made for export to other countries.
Makhteshim Agan of North America (ADAMA), an Israeli firm, makes the new nematicide. The brand name of the product is Nimitz.
On April 13, 2012, the company requested the EPA register the new active ingredient for use on cucumbers, cantaloupes, watermelons, honeydew, squash, tomatoes, okra, eggplant and bell and non-bell peppers. According to the registration decision document, signed and dated Sept. 11, 2014, the registration is unconditional in accordance with the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA).
Fluensulfone is formulated as a technical and one end-use product. The proposed uses include fruiting vegetables, Crop Group 8; and cucurbit vegetables, Crop Group 9. The end-use product formulation is an emulsifiable concentrate.
Methods of application include broadcast, banded and drip irrigation followed by either mechanical soil incorporation – broadcast, banded – or delivery via water, drip irrigation, to a 6- to 8-inch depth. Both human health risks and ecological risk assessments have been completed.
Fluensulfone is a non-fumigant nematicide that provides lower-risk chemical control of nematodes than methyl bromide and other restricted use soil fumigants, the EPA said. Of the seven main alternatives to fluensulfone used in the last five years, six are soil fumigants and the seventh is a carbamate. All seven are restricted-use pesticides, which may pose a greater risk to human health than fluensulfone, according to the agency.
Restricted-use pesticides require special applicator training and certification, reporting and recordkeeping and additional restrictive labeling to protect against human exposure. Soil fumigants can be labor-intensive, requiring tarping and posting of fields.
Nematodes, which are essentially roundworms, are a serious challenge to growers. Although some of the 2,500 species are considered beneficial, others are among the toughest pests with which growers have to contend. Nematodes are hard to identify and demonstrate because they live mostly in the soil. According to one estimate, 10 percent of the world’s crop production is lost because of plant nematode damage.
The few comments received by the EPA regarding fluensulfone’s registration all seemed to be positive. Extension nematologist and professor at the University of California-Davis Becky Westerdahl was pleased Nimitz is being considered for registration.
"As a U.C. cooperative extension specialist in nematology, during the past 25 years I have evaluated more than 100 new products for efficacy against plant parasitic nematodes on a variety of crops," she explained. "Since 2010, I have conducted numerous trials with Nimitz on annual crops in California and have found it to be a very effective nematicide.
"Unlike many products used as nematicides, it is not broad spectrum and has a lower toxicity for non-targets than most, if not all, of our older nematicides. A benefit of Nimitz over fumigant nematicides is that it is effective at pints, rather than at gallons, per acre and this will greatly decrease the pesticide load in the environment.
"Because it is specific for nematodes, Nimitz is not a standalone replacement for broad spectrum fumigants that also control weeds and fungi, but for annual crops, it would work well as the nematicide component of a fumigant replacement program. Growers need multiple alternatives to combat nematodes, both in order to avoid problems that have been associated with repeated usage of the same product and to continue to produce food at a reasonable cost. Nimitz is a valuable tool for use in Integrated Pest Management programs."
The EPA’s decision document and all public comments are available for viewing at www.regulations.gov under the docket number EPA-HQ-OPP-2012-0629.
