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Tasmania worms, flies and lice update - October 2017

Tasmania WormBoss Worm Control Programs

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

Most of the State has had half a spring. Nowhere near as big as last year, but way better than the meagre effort of 2015. The east coast and upper Fingal Valley are a rare class of desperate, while the Bothwell and Derwent Valley areas are fair to OK.  The Midlands, up and down Highway 1 are mostly reasonable, but unless there is substantial rain, it will all peter out.

Because of the spring growth the weaner worm egg counts (WECs) have calmed down. Moreover, few people have been forced to give a lamb-marking drench.  So, what now? Well, firstly, we can be confident that Richmond will win a string of flags. This tends to be independent of the strength of the spring. Secondly, (and almost as importantly), unless there is a big rain on your place, plan to wean early. Aim at about 11 weeks after the start of lambing. This is parasitically and nutritionally vital. You don’t want the lambs and ewes competing for scarce green pasture, or worse still, poxing a clean paddock to the eyeballs by grazing ewes and lambs together on it. The only exception is if you plan to wean onto to irrigated crop.  Otherwise wean early and often.

Two new products to announce:  Bayer have a fly prevention claim for Avenge (imidacloprid).  The registered protection period is up to 14 weeks for long wool sheep and 10 weeks in short wool.  The Export Slaughter Interval (ESI) is 63 days.  In terms of activity it’s roughly in line with Clickzin (low concentration dicyclanil), ivermectin and cyromazine.  In comparison with these drugs it gets slaughtered a bit on the ESI.  So, what may its uses be? Firstly, as an alternative to dicyclanil and cyromazine for short-medium fly control.  Secondly, as a rotation to another compound when cyromazine and dicyclanil have run out in the face of on-going challenge.  It’s the opinion of the Paraboss Technical people that you should use a different active if retreatment is needed.  At this stage I have no intelligence from Bayer on rain fastness.

(Editor's note: I called Domenic Dellosa from Bayer for rainfastness information about Avenge and his reply was:
"Although there were no formal rainfastness studies, rain fell on the sheep on multiple occasions during the registration field trials for efficacy against flies.")

I would also point out that Clik is now available as Clik Extra (29 weeks protection). I will tackle how we might use it next month.

The second new product is a moxidectin triple (moxidectin, levamisole and albendazole) marketed as Tridectin (Virbac).  You know that I am always banging on about using mectin triples for most therapeutic drenches, particularly in the absence of current drench test data, and even more so if your drench test shows that all 3 components are working fair to good (as my English teacher would say).  Moxidectin is the most potent of the mectin compounds, so Tridectin should figure in your thinking.  Virbac has some information to show that the formulation potentiates the activity of both the mectin and levamisole components, so that is a plus.  In my experience resistance to moxidectin and abamectin develop at about the same rate, so if you have substantial abamectin resistance it’s unlikely that Tridectin will be a revolution.  Having said that Virbac have many cases on file where Tridectin has worked when abamectin triples have failed.  A big plus for Tridectin is a 17-day ESI, compared with 28 days for most of the abamectin triples.