Weeds Could Be the Key to Reducing Pesticide Use

Pesticides have something of a bad rep. Those chemicals that are supposed to protect plants by attracting and then killing pests have been linked to the decline of the bee population, contaminated foods, and even depression among farmers.

In a study published last week, researchers at Cornell University put forward a new approach to agriculture pest management—one that doesn't rely so heavily on problematic pesticides.

The solution? Weeds.

The Cornell scientists suggest that rather than removing weeds from farms (usually done to increase crop yield), farmers should keep and incorporate specific plant species as part of a sustainable, integrated pest management system. This approach could both reduce the need for pesticides and benefit crops.

The research, which was published in the Weed Science journal, includes scientists' observations on how the presence of milkweed in a cornfield could protect against the European corn borer, one of the crop's main pests. They found that the milkweed is a habitat for aphids (destructive flies), which provide a nectar food source for parasitic wasps. The wasps then lay eggs inside European corn borer eggs, killing them and thus reducing damage to the corn crop.

It's not the first time that scientists have highlighted the benefits of keeping weeds in crop fields—the Cornell researchers highlight other experiments that demonstrate the positive effects on soil quality, for example. But this research is the first to evaluate the pros and cons of using weeds in an integrated pest control system. Weeds are still a competitor plant to the crop its protecting, after all.

John Losey, co-author and professor of entomology, said in a press release that we mustn't be swayed by the negative connotations of weeds.

He said: "Every organism in an agricultural system plays multiple roles. If management decisions are based solely on the negative aspects, yield and profit can be lost in the short term and broader problems can arise in the longer term."

Speaking to MUNCHIES, Dr Katie Field from the Centre for Plant Sciences at the University of Leeds, echoed Losey's comments. She suggests that weeds could be used for intercropping, an ancient agricultural technique which she describes as "growing different but compatible crop species with non-competing requirements for nutrients or space alongside each other."

Field said: "Using weeds in an intercropping management system is a new idea—frequently intercropping systems are used to reduce weed cover. Farmers often don't consider weeds as anything other than harmful to their crop yield. Using weeds through intercropping could be really important as part of an integrated pest management regime."

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She added: "By providing plants suitable for the predators of the crop pests to live in, it may be possible to reduce the use of chemical pesticides—great news for the wider environment."

So, those weeds you haven't pulled up from your balcony in six months? They're good for the environment, really.