Garlic mustard is an unwanted European invader like purple loosestrife. In woodlands it out-competes native wildflowers like trilliums. On farms, dairy cows that eat it produce milk with a garlic flavour. Garlic mustard spreads quickly because it employs a form of chemical warfare called allelopathy (all-lee-lo-pathy) to suppress or prevent the growth of competitive plants.

Jessie MacAlpine of Woodstock learned from mentor Dr Brent Sinclair, a biologist at University of Western Ontario how garlic mustard produces biochemicals to suppress seed germination of other plants.

“I said ‘oh, so it’s used a herbicide?’” Jessie recalls, but Dr Sinclair didn’t think any one had ever tried it.

When the Grade 10 student at Woodstock’s Huron Park Secondary School confirmed no one had attempted to use garlic mustard as an all-natural herbicide, she was determined to be the first. And determination was needed since Jessie had to try several different methods for extracting the right chemicals from the roots of garlic mustard plants. “My first month of experimentation just produced at lot of unusable data,” the 15-year-old recalls.

On the 6th attempt she found the formulation that proved that 500 grams of the plant extract per litre of water significantly reduced germination, seedlings and root length.

“The most surprising thing I learned was how little research has been done on allelopathy’s potential as a herbicide,” says Jessie, “especially since synthetic herbicides are harmful to the environment as well as human health.”

Since most allelopoathic plants are edible, an all-natural herbicide derived from them should be safe for humans and the environment. And, she notes, many weeds are becoming resistant to synthetic herbicides.

Jessie calculates that treating an acre of ground with her garlic mustard bioherbicide would require 1,618 litres of extract. A substantial amount but she’s confident that could be improved with further research.

The sanofi-aventis Biotalent Challenge has opened Jessie’s eyes to the possibilities of a biology career, she says. “It was amazing to meet and interact with young scientists who are passionate about changing the world.”

Says Dr. Sinclair: “In science fair projects, the important thing is the process, not the results. Jessie has taken an observation of a natural phenomenon (allelopathy) and thought of a cool application.”

Last year, he noted, Jessie produced data on fruit flies that has now been published in peer-review scientific literature.