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Posts Tagged: methyl bromide
Methyl iodide debate continues despite registration
The soil fumigant methyl bromide, which growers have depended on for decades, will no longer be available starting in 2015. Methyl iodide, a potential substitute, is a harmful chemical, but can be used safely with proper precautions, said UC Cooperative Extension weed scientist Steve Fennimore.
"The professional fumigators are really good," Fennimore said. "If the public saw how the companies do the fumigation, they'd probably be more comfortable with them."
Another fumigant, chloropicrin, is widely used in combination with methyl bromide and methyl iodide to provide the most pest-free soil for growers.
"Chloropicrin is really strong against fungi, and methyl bromide is really strong against weeds," Fennimore said. "When you use them together, there's a synergy. They're very complementary."
UC specialist looks into steam cleaning soil
UC researchers are considering the use of hot steam fumigation on coastal central California farms to prepare soil for planting strawberries and new orchards and vineyards. Farmers there have for years relied on methyl bromide, but the phase-out of the powerful soil fumigant is closing in, according to an article in The Packer.
To study the steam method, UC weed specialist Steve Fennimore outfitted a tractor with a boiler that heats steam to more than 300 degrees F. Ten-inch spikes inject steam into the ground.
The article, written by Elizabeth Ashby, said sandy or light soils are the easiest to treat, but Fennimore has had success in clay loam in Watsonville, Calif.
“This machine…there is something special about it,” Fennimore was quoted in the story. “It is surprising how fast it heats the soil. Within two minutes, it will take 60-degree soil and heat it to 200 degrees. It is like a microwave.”
The quick-acting treatment allows growers to steam in the morning and plant that afternoon when the ground has cooled. That stands in contrast to soil solarization, another possible methyl bromide alternative. Under the solarization system, the field is covered with plastic and the sun heats the soil and kills pathogens. Solarization takes six weeks.
One drawback of the steam system, however, is cost. Fennimore calculated that operating the steam machine, labor and fuel run $4,200 per acre. Methyl bromide in California costs $2,700 to $3,000 per acre. Applying steam to raised beds rather than entire fields could cut expenses to about $3,000 per acre.
Future studies will examine less expensive fuels like propane, ways to speed up the steam injection process and spot treatments.
UC specialist Steve Fennimore is studying steam soil treatment.
Scientific panel suggests state ban methyl iodide
The Fresno Bee ran a story on the front page this morning reporting that a scientific panel recommended that the California State Department of Pesticide Regulation reject a request by Tokyo-based Arysta LifeScience Corp. to approve the use of methyl iodide for pest control on California farms and in structures.
The eight-member Scientific Review Committee, chaired by UCLA environmental health sciencies professor John Froines, includes UC San Francisco medicine professor Paul Blanc, UC Berkeley public health professor Katharine Hammond and UC Berkeley environmental health sciences professor Tom McKone.
Methyl iodide was approved by the U.S. Environmental Protection Agency and many other states, but if California rejects the use of the pesticide, the U.S. EPA "may choose to initiate reevaluation of the methyl iodide registration," according to the panel's report to DPR.
"Based on the data available, we know that methyl iodide is a highly toxic chemical and we expect that any anticipated scenario for the agricultural or structural fumigation use of this agent would result in exposures to a large number of the public and thus would have a significant adverse impact on the public health," the panel wrote.
Farmers, however, believe methyl iodide would be an important tool in their arsenal for controlling soil pests in nursery containers and in the field before planting strawberries or establishing new orchards. The chemical could replace methyl bromide, which has been phased out because it damages the Earth's ozone layer.
"The products that we have just don't do the job," Bee reporter Robert Rodriguez quoted Barry Bedwell, president of the California Grape and Tree Fruit League.
According to the Bee article, DPR director Mary-Ann Warmerdam will review the panel's findings and DPR research as she decides if farmers can use the chemical and if so, under what restrictions. The decision is expected "soon."
The UC Integrated Pest Management Program has reported that soil solarization may be an alternative to chemical soil pest control under the right weather conditions. More information is available on the UC ANR Methyl Bromide Alternatives Web site.
Soil solarization is a possible alternative to methyl bromide fumigation.
Fresno Bee story skips ANR nematologist's point of view
Fresno Bee reporter Robert Rodriguez spoke to UC nematologist Michael McKenry for his methyl iodide story, which appeared in today's paper. McKenry's thoughts weren't included in the article, so I'll share some here.
Methyl iodide is a federally approved fumigant that is currently under review by the California Department of Pesticide Regulation. Farmers see it as a potential alternative for methyl bromide, which is being phased out because it reacts with ozone in the stratosphere, diminishing the earth's protective ozone layer. McKenry said methyl bromide will be unavailable in 2012, but it is already very expensive, costing farmers about $2,500 per acre for treatment, compared to $600 per acre 10 years ago.
However, methyl iodide has its own disadvantages, and McKenry feels those will be tough to overcome in California.
The pesticide is a known carcinogen. McKenry believes the protective gear that workers would have to wear for safe application would be problematic. He also said the company plans to label the chemical for a treatment level that is insufficient for adequate pest control. Finally, he said, methyl iodide will be expensive, even more so than methyl bromide, though the company licensed to sell it, Arysta LifeScience Corp. of Japan, hasn't yet shared the cost.
"It is without a doubt an effective product at high enough application rates. If farmers can use 250 pounds per acre, we can replace methyl bromide," he said. "But it only comes mixed with chloropicrin, which doesn't have anywhere near the type of activity against nematodes that methyl iodide has."
The Bee story did include a quote from UC Berkeley chemist Robert Bergman, who is one of many scientists and environmentalists opposed to the use of methyl iodide in the United States.
"We know that even in small amounts it can be very toxic," Bergman was quoted. "And in agriculture, you are talking about hundreds of pounds being put into the ground and covered with a tarp."
A likeness of a methyl iodide molecule.
Activist radio program takes on UC-patented pesticide
They say all publicity is good publicity, so I'll point out a report about UC research that appeared on a blog and radio program titled Uprising - Subverting the Airwaves, broadcast on KBFK radio in Los Angeles and on the Web.
The premise is a proposed substitute for the fumigant methyl bromide, which is being phased out because it has been found to deplete ozone in the earth's atmosphere. The substitute, methyl iodide, was patented by UC Riverside, the story said, and licensed to Arysta LifeScience.
Methyl bromide has been important to the state's strawberry industry. Growers used it to control soil-borne pests and diseases that dramatically reduce strawberry yields. Methyl iodide does not harm the earth’s atmosphere, but many scientists and concerned citizens worry that it increases cancer, causes miscarriages and poses other health risks in humans and animals, said the program's host, Sonali Kolhatkar.
The guest on the show was Susan Kegley, a chemist and consulting scientist for the Pesticide Action Network. She said switching from methyl bromide to methyl iodide is analogous to leaping from the frying pan into the fire.
"This just seems like the wrong direction for California agriculture to be heading," she said.
Kegley mentioned that the California Department of Pesticide Regulation is currently considering the registration of methyl iodide in strawberries, and that the Pesticide Action Network is organizing a petition against the chemical's registration.
"The strawberry industry got together and developed a lot of techniques that would work, but are not in broad practice because (chemical) alternatives are available," Kegley said.
