Collateral damage in war on weeds
BLYTHEVILLE, Ark. — Clay Mayes slams on the brakes of his Chevy Silverado and jumps out with the engine running, yelling at a dogwood by the side of the dirt road as if it said something insulting.
Its leaves curl downward and in on themselves like tiny, broken umbrellas. It’s the telltale mark of inadvertent exposure to a controversial herbicide called dicamba.
“This is crazy. Crazy!” shouts Mayes, a farm manager, gesticulating toward the shriveled canopy off Highway 61. “I just think if this keeps going on ... ”
“Everything’ll be dead,” says Brian Smith, his passenger.
The damage here in northeast Arkansas and across the Midwest — sickly soybeans, trees and other crops — has become emblematic of a deepening crisis in American agriculture.
Farmers are locked in an arms race between everstronger weeds and everstronger weed killers.
The dicamba system, approved for use for the first time this spring, was supposed to break the cycle and guarantee weed control in soybeans and cotton. The herbicide — used in combination with a genetically modified dicamba-resistant soybean — promises better control of unwanted plants such as pigweed, which has become resistant to common weed killers.
The problem, farmers and weed scientists say, is that dicamba has drifted from the fields where it was sprayed, damaging millions of acres of unprotected soybeans and other crops in what some are calling a man-made disaster. Critics contend that the herbicide was approved by federal officials without enough data, particularly on the critical question of whether it could drift off target.
Government officials and manufacturers Monsanto and BASF deny the charge, saying the system had worked as Congress designed it.
The backlash against dicamba has spurred lawsuits, state and federal investigations, and one argument that ended in a farmer’s shooting death and related murder charges.
“This should be a wakeup call,” said David Mortensen, a weed scientist at Pennsylvania State University.
Herbicide-resistant weeds are thought to cost U.S. agriculture millions of dollars per year in lost crops.
After the Environmental Protection Agency approved the updated formulation of the herbicide for use this spring and summer, farmers across the country planted more than 20 million acres of dicamba-resistant soybeans, according to Monsanto.
But as dicamba use has increased, so too have reports that it “volatilizes,” or re-vaporizes and travels to other fields. That harms nearby trees, such as the dogwood outside of Blytheville, as well as nonresistant soybeans, fruits and vegetables, and plants used as habitats by bees and other pollinators.
According to one 2004 assessment, dicamba is 75 to 400 times more dangerous to off-target plants than the common weed killer glyphosate, even at very low doses. It is particularly toxic to soybeans — the very crop it was designed to protect — that haven’t been modified for resistance.
Kevin Bradley, a University of Missouri researcher, estimates that more than 3.1 million acres of soybeans have been damaged by dicamba in at least 16 states.
“It’s really hard to get a handle on how widespread the damage is,” said Bob Hartzler, a professor of agronomy at Iowa State. “But I’ve come to the conclusion that (dicamba) is not manageable.”
The dicamba crisis comes on top of lower-than-forecast soybean prices and 14 straight quarters of declining farm income. The pressures on farmers are intense.
The new formulations of dicamba were approved on the promise that they were less risky and volatile than earlier versions.
Critics say that the approval process proceeded without adequate data and under enormous pressure from state agriculture departments, industry groups and farmers’ associations. Those groups argued that farmers desperately needed the new herbicide to control glyphosate-resistant weeds, which can take over fields and deprive soybeans of sunlight and nutrients.
Such weeds have grown stronger and more numerous over the past 20 years — a result of herbicide overuse. By spraying so much glyphosate, farmers inadvertently caused weeds to evolve resistant traits more quickly.
The new dicamba formulations were supposed to attack these resistant weeds without floating to other fields.
But during a July 29 call with EPA officials, a dozen state weed scientists expressed unanimous concern that dicamba is more volatile than manufacturers have indicated, according to several scientists on the call. Field tests by researchers at the Universities of Missouri, Tennessee and Arkansas have since found that the new dicamba herbicides can volatilize and float to other fields as long as 72 hours after application.
Regulators did not have access to much of this data. Although Monsanto and BASF submitted hundreds of studies to the EPA, only a handful of reports considered volatility in a real-world field setting, as opposed to a greenhouse or a lab, according to regulatory filings. Under EPA rules, manufacturers are responsible for funding and conducting the safety tests the agency uses to evaluate products.
And although pesticidemakers often supply new products to university researchers to conduct field tests in varied environments, Monsanto acknowledged it did not allow that testing on its commercialized dicamba because it did not want to delay registration, and scientists said BASF limited it.
Scott Partridge, Monsanto’s vice president of global strategy, thinks some farmers have illegally sprayed older, more volatile dicamba formulations or used the herbicide with the wrong equipment.
The company has deployed a fleet of agronomists and climate scientists to figure out what went wrong.
“We’re visiting every grower and every field,” Partridge said. “If there are improvements that can be made to this product, we’re going to do it.”