Quick Dips

Thistle-Thwarting Tie-up

AgResearch and ICI Cropcare scientists hope to have a biological control for Californian thistle on the market within three years.

The product being developed is a mycoherbicide, a herbicide based on a naturally-occurring fungus, Sclerotinia sclerotiorum, which was isolated from sick and dead thistle plants collected around New Zealand. The fungus attacks the thistle plants, producing a toxin which kills not only the leaves and stems but also the root system, providing ongoing control.

Californian thistle is one of New Zealand's most widespread and serious pasture weeds. Chemical control is not always effective or economic, and it can damage beneficial plants such as clovers in pasture.

The fungus is pathogenic to many types of plants, and is being investigated for its potential to control other pasture weeds such as ragwort, scotch thistles and nodding thistles.

AgResearch scientists have been working on the project for about two years, and after excellent field trial results negotiated a $600,000 collaborative research licensing agreement with ICI. The major reason for choosing ICI was the company's experience in formulating living micro-organisms. Currently the mycoherbicide is expensive to produce, and large quantities are required to treat paddocks. It is hoped that with ICI's expertise, the scientists should be able to reduce both production costs and application rates.