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South Australia worms, flies and lice update - August 2015

SA WormBoss Worm Control Programs

SA WormBoss Drench Decision Guides

Adelaide: Colin Trengove, Sheep Health Lecturer (UA Roseworthy campus) (

A relatively cold winter with just sufficient rain to encourage pasture and crop growth, but soil moisture reserves are at a low ebb in many areas. The strong indications foreboding El Niño are not welcome, but worms pay little attention to the SOI & SST indicators. 

Recent monitoring has revealed moderate counts, perhaps in response to the cold drier winter in the higher rainfall areas, although the lack of inundation would be expected to assist worm survival. As a consequence, there has been little need for salvage or "knock down" drenching in winter. 

Lamb marking reports across the state reveal above average results with flocks reporting 120–140%. This most likely reflects the relatively good weather through the May-July lambing period. While a drench is recommended at weaning in September/October, prior monitoring is also recommended to assess worm burdens. Absence of worms at this stage of a lamb's life is unlikely, but a negative egg count can save an unnecessary procedure as well as a drench cost.

As soil temperatures rise the corresponding spring pasture growth will reduce worm larvae pick up. This combined with better nutrition for grazing livestock should ensure worm burdens diminish or at least won't progress. The next monitoring in adult sheep will be to indicate the need for a summer drench. An exception to this will be unresolved scouring to assess worm involvement. Any queries please discuss with your local animal health professional. 

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