Mint scent inhibits the growth of weeds

Some plants are very successful in the competition for space, nutrients, and water. They inhibit the growth of their competitors by chemical signals that cause cells of the neighboring plant to die. Scientists of the Botanical Institute of Karlsruhe Institute of Technology (KIT) study this effect for potential use in environmentally compatible bioherbicides.

Hobby gardeners and woodland walkers know the phenomenon that no other plants grow near a walnut tree and that wild garlic and mint displace their neighbors. This chemical warfare is referred to as allelopathy by experts.

"In most cases, this effect in the target plant is caused by chemical signals rather than poisons," says Peter Nick, Professor for Molecular Cell Biology at KIT's Botanical Institute. While wild garlic and mint are immune to the effect of their chemical signals, biological communication triggers self-controlled cell death in the neighboring plant. Scientists think that this mechanism of plant communication may lead to the development of novel, environmentally compatible bioherbicides that specifically affect a certain type of weed without damaging the useful crop.

Cell cultures revealed that the menthone compound contained in the essential oil of the mint activates a process in competing plants, as a result of which microtubules – finely branched, tubular protein structures – destroy themselves. "We found that menthone is particularly effective against dock on mountain pastures," says Dr. Mohammed Sarheed.