Ban sought on tomato-killer lawn spray

By SIMON COLLINS

The Government is being asked to ban a common weedkiller that has affected tomato plants after being recycled into compost.

Auckland compost maker Living Earth says traces as low as five parts a billion of the weedkiller clopyralid in composted grass clippings were enough to cause deformities in tomato plants.

The company has won support from the Ministry for the Environment, the Business Council for Sustainable Development and the Auckland, Waitakere and Christchurch city councils to ban the weedkiller in urban areas.

The weedkiller is sold under names such as Versatill, Kiwicare No Lawn Weeds and McGregor's Turf Weed Control.

It will be allowed in rural areas, where 99 per cent of the clopyralid sold in New Zealand is sprayed on weeds in cereal crops and forests.

The spray does not affect cereals or trees, but can be lethal for vegetables such as tomatoes and potatoes.

It is the first time a ban has been sought on any product because of the recycling of garden wastes as compost, and will be a test case for the Environmental Risk Management Authority.

Living Earth chief executive Rob Fenwick said the problem had arisen only in Christchurch, but the company did not want the use of the spray to spread.

"It's a turf herbicide that you use to get rid of special weeds and clover, and for some reason Christchurch gardeners have used this a lot more than anywhere else," he said.

"It's a very persistent chemical and it does not break down in the compost when the compost gets warm. That seems to extend its life."

In Christchurch, the city council diverted all grass clippings from lawn mowing contractors to the city landfills after the effect of clopyralid was spotted three years ago.

Council brochures advised against using grass clippings contaminated with clopyralid for compost, and some manufacturers put warning notes on their products.

Dow AgroSciences, which makes the product in New Plymouth, supports the ban in urban areas.

Its research and development manager, Brian Husband, said the product's label advised against using it in home gardens.