27 April 1999

Canterbury Farming Focus
Dip Residue Feature

Flies in the face of market demand

by Stuart Edwards, Dip Residues Leader, WoolPro

The clock is ticking for farmers who use plunge and shower dips to protect their sheep from flystrike during summer and autumn.

Latest residue results reveal that as many as one-third of Merino and mid-micron growers will be hurt in the pocket if they don’t change their dipping and shearing practices in the next three years. Hardest hit will be growers who are not accredited to the Fernmark, Merino Integrity or Wrightson Woolcare quality assurance programmes.

By 2002, tough new effluent standards will be applied to woollen mills and scours across the European Union. To meet those standards, they will only be able to process wools which have dip residue levels below 5 parts per million (ppm).

The European Union is home to the most valuable markets for New Zealand fine wools. Our best Merino and mid-micron wools are sought after by spinners and weavers who supply leading fashion houses in Italy, France, Germany and England.

Early data from the latest WoolPro survey of dip residues in Merino and mid-micron wool, shows a significant reduction in organo-phosphate and synthetic pyrethroid residues in quality assured (QA) clips, for a second year in a row. That’s good news for the QA flocks where most of the reduction has occurred.

More than 75 per cent of samples from QA clips had dip residues less than 5 ppm.

Indeed, more than 90 per cent of the average residue levels in QA flocks came from 10 per cent of the clips – those with residues greater than 10 ppm.

For non-QA growers the situation is grim. More than 60 per cent of non-QA clips sampled had residues of more than 10 ppm. At 43 ppm, they had three times the average dip residue level of accredited clips.

This dramatic difference is due to dipping and shearing practices.

To achieve acceptable residue levels, farmers need to have an active residue minimisation policy. In fine wool flocks, that means no plunge- or shower-dipping sheep with more than eight weeks wool.

Strike flies need to be controlled by jetting – either using handjets, or modern automatic races which give targeted dip application – or by the use of spray-on concentrates. Lice is best controlled with off-shears pour-on or shower treatments. Changing the dipping and shearing practices of a life-time is not easy. Especially not in tough seasons like this, where late season fly strike was a problem over much of the South Island.

A warm wet autumn, stock stressed after a prolonged summer drought, and a flush of autumn grass growth causing sheep to scour, provided ideal conditions for strike flies.

The migration south of the Australian green fly added to the problem – especially for Southlanders who experienced this pest for the first time this year.

But the message from the market is clear and consistent. Those growers who ignore it, do so at their peril.

Many farmers who in past years would have saturation dipped their flocks to cope with the unusually late fly challenge, changed tack this season. They are impressed by the good results they have achieved by crutching and jetting round the crutch and across the shoulders.

Others, such as the Awatere Blowfly Busters in Marlborough, have adopted integrated management principles – using plastic fly traps to reduce fly pressure, with remarkable success.

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For more information on effective fly and lice control without excess residues, contact: Stuart Edwards, Freephone 0800 4 Meat & Wool Innovation (0800 496 657).