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Tasmania worms, flies and lice update - December 2014

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

There has been useful rain over the northern parts of the State this month.  Perth has received approximately 100 mm.  Unfortunately, the rain has tapered off in the central and southern midlands, and these areas are still very dry.

The suggestion is to stick to the plan outlined in the last few missives:

  • Wean early (or at least not late).
  • Weaning drench for all lambs
  • Weaning drench/first summer drench for all ewes going back onto permanent pastures.
  • The drench used for the first summer drench must be highly effective.  It’s pleasing to have received lots of enquiry about the new actives (derqantel and monepantel): it shows a level of awareness that may previously have been absent.

The big news this month is the diagnosis of Haemonchus (barber’s pole) on a property south-west of Longford.  While Haemonchus is a feature on Flinders Island, and occurs sporadically in the Tamar Valley and northeast, this is the first time in 25 years I’ve seen it on my patch.  Haemonchus have been an occasional incidental finding on PMs, mostly in the late summer and autumn, but a clinical case (poor sheep as white as sheets) in the early summer is a new occurrence. 

The property concerned runs Coopworth ewes on irrigated pastures.  It’s assumed that larvae from contamination laid down last autumn survived the winter and have multiplied in the spring.  This mob did not receive a pre-lambing drench (indeed, the ewes on this property have been undrenched for about 3 years).

In coming months, part of this column will be dedicated to control options (this will give me time to get up to speed).  In the meantime we must assume that irrigation is, or has the potential to extend Haemonchus’ range.  Be on the lookout for poxy sheep with a high egg count (Haemonchus is a prodigious egg layer), pale gums and not scouring.  While young sheep are exquisitely vulnerable, adult sheep are not inherently immune, as they are to scour worms (black scour and brown stomach worms). 

(Editor’s note: From many years experience seeing sheep affected by barber’s pole worm, sheep generally look really healthy until just before they keel over and die! Tasmanian sheep likely have mixed infections with plenty of scour worms too, causing them to be 'poor 'or 'poxy'.)

The rain and ongoing humid weather has also activated the flies.  Dag control is pivotal.  Please refer to last month’s missive to see control options.

Have a happy Christmas and New Year.