WASHINGTON, May 25, 2016 - Cotton growers are worried about losing another tool to fight the tarnished plant bug if EPA’s new label for sulfoxaflor is approved.
The Dow AgroSciences product, sold under the trade names Transform and Closer, was pulled from the market last fall after the 9th Circuit Court of Appeals said Sept. 10 that existing studies did not adequately characterize the risk to honey bees.
“Given the precariousness of bee populations, leaving the EPA’s registration of sulfoxaflor in place risks more potential environmental harm than vacating it,” the court said.
The newly proposed label, on which EPA is accepting comments until June 17, would restrict applications on “bee-attractive” crops to post-bloom and impose other conditions in order to achieve “essentially no exposure to bees on the treated field.”
But one way it would achieve that result is to prohibit sulfoxaflor use on “indeterminate blooming” crops such as citrus, cotton, cucurbits (such as melons, pumpkins and squash), soybeans and strawberry.
According to estimates by the U.S. Geological Survey, about 21,000 pounds out of a total of 23,000 pounds of sulfoxaflor used in 2013 was sprayed on cotton fields. The remaining product was used on vegetables, fruit, orchards and grapes.
EPA’s proposed registration includes crops in three categories: “non-bee attractive” crops such as barley, wheat and triticale; pre-bloom application for crops such as leafy vegetables, and post-bloom application for bee-attractive crops such as berries, canola, fruiting vegetables and pome fruits, among others. (The full list is here.)
Dow AgroSciences is working to get cotton back on the label.
“Our intent is to recover all the uses that sulfoxaflor had,” Dow AgroSciences spokesman Garry Hamlin said, adding that the company is “in the process of providing data” to EPA. “We continue to maintain, based on considerable evidence, that the previous registrations of sulfoxaflor were protective of pollinators.”
He pointed to EPA’s announcement of the proposed registration, in which the agency said it had determined that “when used according to the proposed label requirements, sulfoxaflor is safe for everyone, including infants, children and agricultural workers. The agency has also determined that overall, sulfoxaflor presents a low risk to aquatic and terrestrial organisms and low residual toxicity to pollinators.”
In the meantime, cotton growers are counting on obtaining emergency exemptions under Section 18 of the Federal Insecticide, Fungicide, and Rodenticide Act, in order to use sulfoxaflor. The comment period closed May 18 on a request by the Tennessee Department of Agriculture, Arkansas State Plant Board, and Mississippi Department of Agriculture for authority to use the chemical on up to 168,750 acres of cotton in Tennessee, 320,000 of acres of cotton fields in Arkansas and 337,500 acres of cotton fields in Mississippi.
Grain sorghum growers in nine Southern states got a Section 18 exemption earlier this month to use sulfoxaflor to control sugarcane aphids. Approval in Texas for use on sugarcane aphids in sorghum fields was granted in April.
Don Parker, an entomologist and manager of Integrated Pest Management (IPM) with the National Cotton Council, said it’s important to have sulfoxaflor because tarnished plant bugs, especially in the mid-south, have developed resistance to chemicals such as organophosphates and pyrethroids. Sulfoxaflor has become part of a rotation using a variety of chemicals.
“You take that out of the mix, it undermines the whole strategy,” he said.
As Clark Carter, who grows cotton on 400 acres in the Mississippi Delta, said in comments supporting the Section 18 application, “Multiple applications of less effective insecticides are required to replace the more effective and less used Sulfoxaflor (Transform). Also, multiple applications of less effective insecticides increase secondary pests that are also hard to control.”
Without sulfoxaflor, “we are at risk of using more insecticides to control more insects.”
And Jeffrey Gore, associate professor at Mississippi State University’s Delta Research and Extension Center, said that growers have been able to decrease their average number of insecticide applications by using sulfoxaflor – while also increasing yields.
“The availability of sulfoxaflor had given growers the additional mode of action necessary to fully implement the IPM program and the area planted to cotton has been increasing,” Gore said in comments supporting the Section 18 application. “Over the last few years, the use of sulfoxaflor has replaced applications with high rates of neonicotinoids and organophosphates tank-mixed with pyrethroids.”
Neonics have been under fire for their toxicity to bees, but neonic manufacturers say the connection between neonic use and bee losses is unproven. EPA is currently reviewing the effect on pollinators of registered neonicotinoids while simultaneously suspending approval of any new neonics.
Sulfoxaflor is in the sulfoximine class of insecticides and the only member of a subclass that targets a specific receptor in insects. Transform and Closer became the first two sulfoximine insecticides to hit the market when EPA approved their use in 2013.
Although cotton fields have absorbed the largest share of sulfoxaflor applications, orange growers battling the Asian psyllid also have used the product.
The removal of citrus from the proposed label is “unfortunate,” said Mike Rogers, director of the University of Florida’s Citrus Research and Education Center. “It can be a useful tool, particularly during the bloom period.”
Rogers said the jury is still out on the effectiveness of antimicrobial products recently approved for use on citrus. “It may take a couple of years to see the benefits,’ he said.
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