AgResearch seeking diseases able to wipe out Californian thistle

AgResearch scientists need farmers' help in a two-year project aimed at wiping out Californian thistle.

Graeme Bourdot, weed ecologist and head of the project's field sampling team, wants farmers with diseased thistle on their land to get in touch.

A team of scientists and technicians will survey the thistle population nationwide looking for root pathogens - micro-organisms that cause disease - to develop into a biological control agent.

"Previous work on the Californian thistle shows that it is the roots, not the seeds, which propagate this weed from year to year," Bourdot said. "The roots have buds that act as a survival system that gets it through the winter in established pastures."

He said stock generally did not eat the thistle, which can cover enormous amounts of pastoral land.

"It is worth hundreds of millions of dollars to the sheep farming industry alone each year in terms of lost productivity and the use of herbicides, some of which damage clovers.

"The person that comes up with the solution for Californian thistle probably won't get the Nobel Prize.

"But the farming community will be very happy that's for sure."

Farmers with a "particularly interesting disease" in Californian thistle can call Bourdot on (03) 325-9973.

The AgResearch study follows a project managed by the Clutha Agricultural Development Board to investigate a thistle-eating weevil.

If the weevil successfully passes trials and environmental assessments, it will be released in Southland, Otago and Manawatu-Wanganui in 2007, and nationally by 2011.