Glenn Waller's 100 acres of soybeans in Washington County, Georgia, are the highest yielding in the state. But the "Mr. Efficiency" award winner is worried about rust.
Soybean farmers in the Southeast survived a bout with the crop-destroying fungus in 2005 by using pesticides to halt its spread. But Waller remains worried about a rust resurgence.
"I'm afraid we're going to kind of put it on the back burner and it's going to jump back up and get us,” he said.
Waller, who has farmed for 51 years, increasingly has turned to fungicides to ward off pests and increase his crop yields. Farmers around the country are doing the same, causing an unprecedented surge in fungicide use. But as widespread contamination of waterways near these farms emerges, experts warn that there is inadequate environmental monitoring and information on the chemicals' safety.
"It's concerning," said Jason Belden, an environmental toxicologist at Oklahoma State University. "We have limited toxicological data for a lot of these compounds."
Fungicides are contaminating the majority of water bodies tested in states where there is heavy use, such as in Maine, Idaho and Wisconsin. Some are known to be highly toxic to aquatic creatures, but little is known about whether they are actually harming frogs or other animals in the environment. The potential threats to people are unknown, with new research on lab mice linking them to obesity.
Farmers have historically sprayed fungicides to stop disease. But over the past decade, in an effort to squeeze extra bushels from their crops, they have been spraying more kinds of fungicides on more acres. Wheat, corn, soybeans, citrus and cotton are among the crops that often are sprayed.
The fungicide explosion prompted Kathryn Kuivila, an environmental organic chemist with the U.S. Geological Survey, to see if fungicides were escaping farms and winding up in nearby streams. In a 2012 study of 33 fungicides used on potatoes, Kuivila's lab found that 75 percent of surface waters tested and 58 percent of ground water samples were contaminated with traces of at least one fungicide.
A fungicide called boscalid – used on a variety of crops from food to turf grass – was the most common, found in 72 percent of water samples. The team tested 24 bodies of ground water and shallow water in Maine, Idaho and Wisconsin; the scientists noted that the results may vary nationwide.
The fungicides were found below levels that would kill creatures at the bottom of the food web, such as zooplankton and amphipods, the authors said. But Belden said that doesn't mean there's no threat. Fungicides degrade rapidly so monthly testing in water might not "see all the pulses" of fungicides application, he said. More work is needed to get a better idea of how much aquatic creatures are exposed.
"Is it a red alert that these things should be banned? I don't think so," Belden said. "Is it an alert that we need to do a lot more research relatively quickly to figure out what's going on? I do think that."
There is little information from manufacturers on how much is applied to crops. But all signs suggest that fungicides are now in vogue.
Spraying of soybean crops quadrupled between 2002 and 2006 in an effort to fight Asian Soybean Rust, according to the latest data available from the U.S. Department of Agriculture. Rust is a windblown disease that attacks soybean leaves, causing lesions and eventually killing the plant.