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Tasmania worms, flies and lice update - April 2016

Perth: Paul Nilon, Nilon Farm Health (pandonilon@bigpond.com)

After the big break in late January, and follow-up rain for many areas in March, things have gone decidedly bad again. All sheep producing areas except the upper Fingal Valley and parts of the east coast are now as dry as they were before the January rain. With winter just round the corner (we’ve had 2-3 frosts here in Perth) there is little time left for rain and pasture growth.

Not surprisingly, worms have remained a non-issue. I cannot remember a time when the WECs have been so consistently and predictably low for all classes of sheep and nearly all pastures. Even those who have irrigation resources available have finished lambs as early as possible to free up the irrigated pastures for other classes.

So, the message this month is to enjoy the lack of worm worry while you can. It may alleviate the stress of mounting grain bills.

Below is a picture of a manky irrigation drain on one of our upland properties. This place is fluke central, and the drains that collect water from flood-irrigated paddocks harbour the snails that host the intermediate fluke. 


The drains and swampy margins are where the liver fluke snails live and  are often the only bit of green feed available to sheep. Source: Paul Nilon
The drains and swampy margins are where the liver fluke snails live and are often the only bit of green feed available to sheep. Source: Paul Nilon

The point of this dissertation is twofold: firstly, fluke habitat has expanded a deal in the last 10 years or so due to irrigation. The main distribution channels and rivers are not the issue; the drains and swampy margins are where the snails live. Secondly, these ditches and dribbles are often the only bit of green in a sea of droughted desolation, so they attract stock like Vermont merinos attract flies. Consequently, we can expect fluke problems in drought years as much as in wet years.

Pale, dead and dying sheep are a good hint. Fluke are extraordinarily pathogenic. You can confirm the diagnosis by a blood Elisa test, or (at this time of the year) a fluke sedimentation test on faeces.

Finally, fluke transmission halts after a few good frosts. The highland property pictured has had a few already. Most lowland places may need to wait a month or so, but if you have a fluke problem a late autumn drench is an important time for strategic control.