20 Jan 2014

Scientists ask West Coast farmers to help track clover pest

8:23 am on 20 January 2014

Scientists are asking farmers on the South Island's West Coast to help them keep track of one of the country's worst pasture pests, which has spread into the region, so they can control it.

The clover root weevil, which can cause serious losses of white clover in pasture, is now established through most of the country, including the northern half of the West Coast.

AgResearch insect scientist Scott Hardwick says they have found potentially damaging populations of the weevil north of Greymouth, but so far only one infested site south of there.

Dr Hardwick says they're keen to hear from farmers who think they've got the pest in their paddocks, so they can ensure a tiny parasitic wasp introduced to control the weevil is also present.

He says normally the wasp travels with the weevil as it spreads, but that may not be happening as effectively on the wetter West Coast, and its numbers may need to be boosted.

Dr Hardwick says clover root weevil is now known to be present from Greymouth north and the parasitic wasp has a patchy distribution within that area.

He says the wasp has travelled with clover root weevil, but AgResearch may consider dropping the wasp into infested pasture before the weevil numbers increase and start causing significant amounts of damage.

Dr Hardwick farmers can check for clover root weevil infestation by looking for the distinctive U-shaped notches the pest makes on clover leaves.