Using technology to pinpoint problem weeds

U.K. researchers create inexpensive, in-field herbicide resistance test tool

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Britain’s island geography has been a major barrier for invading forces throughout history, but it’s not so effective at stopping the spread of invasive weeds.

That’s why United Kingdom researchers have developed an inexpensive, convenient tool to help farmers identify resistant weeds, specifically black grass, as early as possible.

Black-grass is to the U.K. what Canada fleabane is, or waterhemp might be, to some Ontario farmers. According to Robert Edwards, professor of natural and environmental science at Newcastle University, the pest made serious incursions across the English Channel in the 1980s.

Why it matters: Quick resistance identification tests could help Canadian farmers better monitor resistance in their fields, resulting more responsive control.

Since 2009, black-grass is the top problem weed in the U.K. Just 12 plants per square metre can seriously deplete grass crop yields. It currently infects three million acres of arable land in the U.K.

Significant herbicide resistance issues

The challenge of controlling black-grass in grass crops, particularly winter cereals, continues to build as herbicide resistance problems mount.

Robert Edwards.
photo: Matt McIntosh

“The problem comes from a high dependence on chemical controls,” says Edwards. He adds the U.K.’s regulatory system also constrains farmers by limiting the types of chemistries they can use. There are currently only three main herbicides that growers can employ against black-grass. The switch to lower tillage systems in the last several decades has also been a contributing factor.

Black-grass is genetically diverse. Because control options are so limited, says Edwards, it’s not uncommon for farmer control efforts to be ineffective.

A tool for more focused control

Testing for resistance is a critical solution. As described by Bayer’s U.K. Crop Science division, knowing whether black-grass is herbicide resistant can help farmers determine application timing, avoid unnecessary applications — as well as what chemistries will work — and other longer-term management strategies.

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But sending samples away for testing is not always practical. To meet farmer needs, Edwards and his colleagues developed the black-grass resistance diagnostic tool, known as BReD, which is inexpensive and can be used by farmers in the field.

The tool is described as a “lateral-flow device” resembling a pregnancy test. Originally based on a more costly tool used to identify fungal spores in the field, growers use the device by applying a leaf sample on the device.

In five minutes, a series of red lines appear, the layout of which illustrate whether resistance genes are present.

By using it across the field, farmers can better map non-target-site, herbicide-resistant weed populations. Edwards adds it can help avoid the “classic control method” of flipping between different modes of action in herbicide applications, which he says actually hurts their chances of managing non-target resistance.

“What we want is to eventually make a digital agronomist,” he says.

Focusing on problem weeds in Canada

The BReD diagnostic tool was developed after Edwards and his colleagues spent years analyzing black-grass genes — as well as proteins within those genes and other metabolic changes — in order to find the origin of its resistance. Eventually, they determined one specific gene as the source of most herbicide resistance. This is what the BReD tool identifies.

Now his team are collaborating with researchers in other parts of the world to expand the tool’s scope. Edwards says this includes working with Canadian agronomy companies to apply the technology to wild oats, a major weed of the Prairies.

Eventually, he says they also hope to improve the technology by giving it the capability to make agronomic recommendations based on plant analysis.

About the author

Contributor

Matt McIntosh

Matt is a freelance writer based between Essex County and Chatham-Kent. He is interested in all things scientific, as well as rock n' roll, hunting and history. He also works with his parents on their sixth-generation family farm.

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