UI scientist studies spread of harmful plant
CHAMPAIGN — Horseweed is the bane of soybean farmers, straying into their neatly planted fields and in some cases drastically reducing yields.
That's one reason Junming Wang, an atmospheric scientist at the University of Illinois State Water Survey's climate-science section, is using balloons — yes, balloons — to study the spread of this pesky plant, also known as marestail.
You may have seen the red, yellow and white balloons floating above a university farm just south of Windsor Road, along First Street.
They're part of a government-funded study to see how far seeds and pollen can travel — research that's important in an era of genetically modified plants or "super weeds" like herbicide-resistant horseweed, Wang said. Both can, and do, affect adjoining crops, and Roundup-resistant horseweed is blamed for reducing soybean yields by as much as 90 percent, he said.
The research is of interest to seed companies and the U.S. Department of Agriculture regulators, he said.
Wang's atmospheric science group received a three-year, $500,000 grant for the study last December from the USDA's Agriculture and Food Research Initiative.
Seeds and pollen can travel horizontally but also vertically, as high as 300 feet above ground level, where they can go much farther aided by winds, he said.
The balloons have instruments at different elevations that sample the seeds and pollen in the air. The motorized device is called a "roto-rod," which spins and catches the seeds, he said.
Wang and his team also use ground-based devices that catch seeds and pollen at various distances downwind from the plants, as well as anemometers to measure wind speed and direction.
They started the experiment about a month ago, during the peak horseweed pollen season, and will be out there for another week or two, he said. The measuring will resume next summer, he said.
So far, it's working great, Wang said: "We've got a lot of data."
Horseweed seeds are heavy, he said, so they weren't expected to travel too far. But on one windy day, researchers found a square-meter patch with 100 seeds more than 500 yards from the source plant.
"That's about 10 seeds per square foot," he said.
Wang's co-investigator on the project, Professor Neal Stewart of the University of Tennessee, is studying the molecular mechanisms involved in the transfer of herbicide tolerance from the "superweed" to regular horseweed plants, which then produce resistant seeds.
Information gleaned about seed or pollen travel will help scientists understand the seed-dispersal process and "outcrossing" by horseweed and other crops — the genetic transmission of a characteristic from one group of plants to another.
The overall goal of the project is to develop user-friendly online tools for regulatory agencies, industry, farmers and the public that would show how far pollen/seeds can be dispersed and offer guidelines for how to prevent outcrossing under different environmental conditions, including buffer zones for planting.
"That's very useful for the seed companies," Wang said, or government agencies that want to set up rules to avoid biological contamination from genetically modified plants.
Wang has used the balloons to study genetically modified maize in Connecticut, but he believes this is the first time they've been used at the UI. He was hired by the survey about a year ago, and before that worked at Tennessee State University.
He said the research also will be applicable to people with asthma and related conditions, as it measures how many pollen grains the plant can release, how far they travel and their concentration in the air, he said.
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