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Tasmania worms, flies and lice update - November 2014

Perth: Paul Nilon, Nilon Farm Health (

An opportunity to do a “big lap” gave a better idea of the state of the state.  North of Epping, things are Rosie.  Between Epping and Oatlands it's bad to very bad, with the York Plains resembling the Gobi Desert (in a good year, it should be added).  South of Oatlands, the upper Derwent Valley and the Bothwell area are fair to good, due of all things a late rain that fell as snow above 400m the first weekend in November.  The Fingal Valley is pretty desperate, except for the very top end and the east coast is as dry as an Indian test pitch.

Weaning is under way, and marking finished for all but the latest lambers.  A surprising number of clients resorted to a lamb marking drench, and in a few cases a post-marking/pre-weaning drench.  These were sometimes unnecessary, but there is nothing like a dry spring to get people twitchy with resultant poor decisions.

As for last month, the advice is to wean as early as possible consistent with marketing plans for suckers.  Don’t let the remaining green tucker go down the necks of corpulent ewes.  Give it to the lambs.  Drench at weaning, which will count as a first summer drench.  Ewes going back on to perennial pastures should also be drenched unless they received a long acting product pre-lambing.  This is a great opportunity to get better pasture decontamination than has been possible for the last few years.  Ewes destined for a holiday at the health farm (bush runs and the like) can remain undrenched.

Worm egg counts (WECS) are a bit like shares:  you only worry when you look at the value.  Thus some of the panicked drenching resulted from people doing WECs immediately before marking and finding results of 400 epg to 700 epg.  In my experience this is not unusual and not cause for concern unless the ewes and lambs are dirty, the ewes light and the lambs looking poorly or if they have no tucker going forward. 

In October, mention was made of a risk management approach to chemical fly control.  To date it’s not been so humid or warm that flies have become active.  This can change rapidly.  The table shows the choice available in fly preventives:







Cyromazine 60g/l

Vetrazin Sprayon





Cyromazine 500g/l

Vetrazin liquid





Dicyclanil 50g/L

Clik Sprayon





Dicyclanil 12.5g/l






Ivermectin 16g/L

Paramax concentrate





Spinosad 25g/L






1:  Does the product kill maggots/treat existing strikes.  2: Export slaughter interval.  3: Wool harvesting interval

Now whenever you list products, there is always a buggerup and manufacturers feel aggrieved because their product is not mentioned. So, the “example” is the first product on the market/the colloquial name.  All but Spinosad are off-patent and there are many examples from different companies.  Always check the withholds.  There are some variations between products with different concentrations (e.g. Dicyclanil 33g v 50g) and substantial differences between different methods of application for the same active. The “duration” is my experience with the product:  it can vary greatly with challenge, rain and wool length. Finally, I’ve excluded products whose primary purpose is different (e.g. Dicyclanil/Diflubenzuron and mectin capsules).

The balancing act is between duration of activity and withholds.  Although most producers are aware of the ESI, WHI often flies below the radar, and your wool marketer may have special requirements.  This is particularly important for lamb shearing of merinos.

The final consideration is active strikes.  I frequently encourage clients to treat these strikes individually with or without crutching of the whole mob.  The reality is that there are many covert strikes and it’s not always easy to get a shearer between Christmas and New Year.  The days of spiking Vetrazin with an OP have (thankfully) long gone, so if you want to treat active strikes you may have to accept a relatively short protection period.

Still, there should be enough options to meet most situations.  If in doubt talk to your vet or have a look at FLYBOSS.

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