Vineyards stumped by rye


Ryegrass resistant to glyphosate - a basic component of popular herbicides such as Roundup - is a more widespread problem for Marlborough vineyards than previously anticipated, AgResearch scientist Trevor James said yesterday.

Glyphosate-resistant grass was first discovered in New Zealand in December last year on a Marlborough vineyard, and tests since then confirmed the problem throughout the region.

Glyphosate is commonly used in vineyards to combat weeds between the vines.

Mr James said vineyards had used glyphosate exclusively for many years because it was cheap and effective and left no residues in the soil.

He said a combination of chemicals would reduce weed growth but could cost twice or three times as much, and leave residues.

"We can recommend different chemicals. We will eliminate the problem. It is not dire in that respect - we can get back to square one again. What makes [glyphosate] special, and so widely used, is there is nothing that replaces it exactly."

He said the next step would be for scientists and other relevant parties, including the Government and chemical firms, to get together and come up with a solution that could be adopted by the wine industry.

Marlborough Wine Growers chairman and vineyard owner Dominic Pecchenino said the finding meant the industry needed to use different types of chemicals rather than just relying on one type of herbicide.

"It will have an effect on your bottom line, and you may go from spending $5 to $20 a litre [for herbicide], but in the grand scheme of things it is not going to put out anyone out of business."

New Zealand Winegrowers sustainability manager Philip Manson said having to use other kinds of herbicides did not necessarily jeopardise the industry's commitment to sustainable environmental practices.

"We will have to look at what to recommend to avoid resistance. If you use agrichemicals you need to bear in mind resistance, and take steps to avoid it."

He said various techniques could be used to address the problem. New Zealand Winegrowers would look at the options before giving advice to its members.

The Marlborough Express