21 December 2001

Herbicide resistant GM crops offer bright future

CROPS genetically modified to resist total herbicides offer benefits, even if volunteers emerge from other GM herbicide-tolerant crops resistant to the same chemical.

That is the opinion of Windsor Griffiths, chairman of the part-government-funded BRIGHT project, set up in 1998 to study the implications of growing GM herbicide-tolerant crops.

His comment comes after GM volunteers resistant to the broad-spectrum herbicides glyphosate and glufosinate emerged in GM herbicide-tolerant sugar beet at trial sites run by IACR Brooms Barn research station in Suffolk, Morley Research Centre in Norfolk and NIAB, Cambridge.

"These trials allow us to look at a worst case scenario deliberately created where a GM crop contains volunteers from a previous GM crop," explains Mr Griffiths.

A key finding is that the GM volunteers can be successfully controlled using conventional beet herbicide sprays, says NIABs Jeremy Sweet, co-ordinator of the £750,000 four-year project.

"The timing is critical." With Roundup-Ready (glyphosate-tolerant) and Liberty-Link (glufosinate-tolerant) crops growers can wait until weeds are quite large and still control them with no loss of yield, he explains.

"But delaying application of conventional beet herbicides doesnt control volunteer oilseed rape very well, so we had to spray earlier." Most conventional treatments have to be applied before the weeds have two-leaves, he notes.

Mr Griffiths does not think the latest findings take some of the potential shine off growing GM herbicide-tolerant crops. "In fact it shows that a combination of GM crops and conventional treatments allows the growing of more than one GM crop in the rotation. Using the GM-associated herbicide on GM beet also allows you to control weed beet, and thats a key benefit."

Compared to conventional methods the number of treatments for full weed control will be cut, he adds.

Being able to tackle grass weeds successfully in GM beet also means the previous cereal stubble could be safely left unsprayed, he suggests. "That could have environmental benefits for birds." &#42

BRIGHT SIGNS

&#8226 GM vol OSR in GM beet no problem.

&#8226 Conventional herbicides required.

&#8226 Overall herbicide load reduced.

&#8226 Valuable weed beet control.

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