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Western Australia worm update - May 2013

Brown Besier, DAFWA, Albany (brown.besier@agric.wa.gov.au )

The worm year has well and truly commenced in WA, with variable amounts of green feed on most properties for a few weeks, and the winter frontal rainfall pattern having started.

Depending on the extent of green cover, worm development will be either starting now or will be well under way. Where there has been a good cover of green pasture for some time, there is the potential for earlier worm problems than in most years.  This is especially likely if summer drenches were not fully effective, and some worms “leaked” through summer because not all were killed.

It is strongly recommended worm egg counts be checked in weaners and hoggets in the next 3-4 weeks, as invisible burdens may be reducing growth rates, and also setting pastures up for winter worm problems.

For ewes due to lamb in the next month or so, there should be no need for a pre-lambing drench if the recommended autumn drench was given with an effective drench type. However, if no autumn drench was given, or there is a query over how effective it may have been, worm egg counts should be taken so treatment can be given before lambing starts, if needed. An absolute maximum of 200 eggs per gram should be allowed at this time, ideally under 100 eggs per gram.

A Barbers Pole worm warning: the early pasture growth in coastal areas has increased the risk of this unwelcome visitor. The main concern is in ewes due to lamb in June: if no drench was given say less than 6 weeks before lambing, worm egg counts should be taken. If there is a high Barbers Pole level, the long-acting drench closantel may be advised, to give peace of mind against disease outbreaks while the ewes are lambing.