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South Australia worm, flies and lice update - April 2014

South Australia: Colin Trengove, Sheep Health Lecturer, UA Roseworthy (

SA has benefited from an unusual weather pattern to kick off an early start for 2014. Substantial rainfall in February followed by excellent rain 6 weeks later was brought about by cyclonic disturbances from the north resulting in only the south east missing out. This has allowed many farmers to complete much of their seeding by late April. Warm oceans off WA are now forecast to bring a further 20–50 mm by the start of May. With the grape harvest almost complete, this should top off the best start to the year in recent times.

Even the predictions of El Niño later this year won't dampen (or is that dry up) farmers’ enthusiasm.

It would be expected that these unusual summer/autumn rains would have produced a substantial worm and fly risk. However, this has not occurred. Recent monitoring around the State reveals less than a third of WECs have indicated a need for a drench and even these have only shown moderate worm burdens. This may reflect the dry finish in 2013 ensuring relatively low worm risk pastures in the lead up to 2014.

Discussions with producers around SA indicate minimal fly concerns despite the unseasonal rainfall to start the year. This is good news considering many mid and upper north, Riverland and mallee producers received around 50 mm of steady rain twice on lengthy fleeces.

The forecast rain is bound to spike worm larval emergence and so pre-lambing monitoring (and maybe drenching) is advised to minimise the risk of unexpected worm burdens. To counter this, early green feed has ensured lambing ewes are in good condition and so better able to suppress worm burdens. Depending on weather conditions during lambing above average lambing would be expected given the optimal start to the season.

Animal Health Officers report lice detections in stock markets remain a regular occurrence. This endemic disease persists unabated and is unlikely to change without a concerted industry campaign. The on the spot fine for presenting lousy sheep for sale appears to have little impact other than a transitory reduction in discretionary expenditure for the transgressor. Given much of the cost associated with lice are chemical and labour costs it is disappointing, or perhaps not unexpected, that the state prevalence has remained similar for over 30 years.

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