Forage Science

Research provides new guidance for West Coast farmers on pests

3 April 2017
New guidance for West Coast farmers | AgResearch NZ

AgResearch scientists are set to present new guidance to West Coast farmers on dealing with some of the region’s worst pests after years of in-depth research alongside locals.

Over the past three years farmers in the West Coast Pest Management Group have taken part in a project funded by the Ministry for Primary Industries’ Sustainable Farming Fund to improve the understanding of pests that threaten pastures.

“This research is about providing farmers on the South Island’s West Coast with the tools to tackle these pests, before the long-term damage is done to their pastures and bottom lines,” says AgResearch Senior Scientist Sarah Mansfield.

“The research has focused particularly on the porina caterpillar, which if unchecked has the potential to seriously reduce the quality and production of pasture. The farmers monitored the timing of the porina moth flights on their properties to determine the most effective time to apply measures to control the pest and prevent damage.”

“With the data collected by farmers, combined with sampling of the caterpillar populations by AgResearch scientists, we can now make recommendations for managing porina on the West Coast.”

“We will be preparing a regional pest management guide over the next few months based on the outcomes of this research, and from an earlier Sustainable Farming Fund project focused on another pasture pest, the Manuka beetle. There will also be the opportunity for people to hear first-hand about the findings to date at upcoming public meetings.”

In addition to the funding from the Sustainable Farming Fund, the work on porina has also been supported by DairyNZ, the Ministry of Business Innovation and Employment, Westland Milk Products and Landcorp.

“It’s been a great example of famers working alongside scientists, government and industry to support the rural sector in this region,” Dr Mansfield says.

The public meetings are as follows:

  • 10 April 2017 - from 7pm at Whataroa Community Hall, 57 Main Rd, Whataroa
  • 11 April 2017 - from 7pm at Kokatahi Hall, Upper Kokatahi Rd, Kokatahi.
  • At Landcorp, Cape Foulwind (time and date TBA).

Those interested in attending the meetings and wanting more information should contact their milk supply manager at Westland Milk Products, or Richard Townsend at AgResearch –

Additional notes on porina:

At low densities, porina are direct competitors with stock for foliage and at higher densities plants are destroyed allowing inferior plant – or weed – species to establish.

Young porina caterpillars construct silk-lined casings on the soil surface, and as they grow they construct permanent burrows in the soil. They emerge from their burrows at night to feed, severing grass and clover leaves at the base of plants and dragging them back to their burrows where they are eaten.

Moths fly in large numbers during spring and early summer. They do not feed, but each moth can lay up to 3000 eggs on the pasture surface. Caterpillars and the damage they cause are mostly noticeable from April to September.

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