2 March 2000
First organic herbicide in five years

ORGANIC farmers could within a few years be using their first broad-spectrum herbicide – a fungus-derived protein which attacks broad-leaved weeds.

The protein, taken from the soil fungus Fusarium oxysporum, kills the leaves of many broad-leaved weeds, but does not damage crops such as corn, reports New Scientist magazine.

Weeds are not killed outright, but are stunted until new leaves grow back.

“If you can delay the weed problem, the crop will outgrow it and shade it out,” says Bryan Bailey, a plant pathologist with the US department of agriculture in Beltsville, Maryland.

Organic farmers already use insecticides and fertilisers certified as organic, but there are no herbicides cleared for use on their crops.

Researchers must find an organic surfactant – a substance which would allow the protein to stick to leaves – and conduct toxicity and allergy tests.

If problems can be overcome, Mr Bailey predicts the product could reach the market in five years.