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Tasmania worms, flies and lice update - November 2019

Tasmania WormBoss Worm Control Programs

Tasmania WormBoss Drench Decision Guides





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

Wind is the feature of the weather report. Wind and cold weather, and wind and warmish weather. Does not matter which one: both have been truncating the spring. The southern midlands and Derwent Valley now look quite ordinary. The east coast and Fingal Valley are hanging onto the rain event of early September.

Worm-wise, it’s the quiet time between marking and weaning. There’s little to report. The reminders are the same as last year: drench the lambs at weaning, and also the ewes if they are staying on permanent pastures. This will be our first summer drench. Make sure you use a working drench, that is, one with as close to 100% efficacy as possible. Ninety-five per cent does not cut the mustard in this case. It’s the ideal time to use one of the new actives (derquantel or monepantel), but watch the Export Slaughter Interval (ESI) if using monepantel on lambs.

Spring Memes: I’m not thinking of nesting swallows with their attendant piles of sh1t on the veranda, nor endless gardening duties. The spring meme is a long queue of cars behind a mower or bailer as it moves between properties. There have been plenty of examples in the last 3 weeks. This means that spring is winding down quickly. Get your lambs weaned sooner rather than later. I’ve heard all the gumpf about the ewes being in good condition and how well they are milking. If the grass is changing colour (which it is/has) get the lambs weaned. This is parasitically and nutritionally sensible. The only reason not to wean now is the likelihood of better green tucker in a few weeks (e.g. clover being irrigated up or rape coming online).

Snail-Paced Invasion: The thesis of one federal ‘polie’ is the risk of being overrun by Asians and (more recently) Muslims. Other members of the government are warning about an invasion of the mind through interference in university courses and politics. Fear not: an invasion [of snails] is much slower, but potentially quite serious.

The main intermediate host for liver fluke is the aquatic snail Lymnaea tomentosa. Another snail, Pseudosuccinea (formerly Lymnaea) columella, has been found in several states, including Tasmania. Pseudosuccinea is an adequate intermediate host for liver fluke. Importantly, it can survive in a different range of environments to L. tomentosa. Most importantly, it can live in ponds and dams, whereas L. tomentosa cannot. Another factor is that Pseudosuccinea is revered as a potent, opportunistic invader.

There is at least one report of P. columella from southern Tasmania. In the last few days, it has been found in the north of the state (location is unknown to me). It is possible that this snail may be more widespread than the few confirmed identifications. After all, there is little incentive to have identified any aquatic snail minding its own business in your pond.

So, if your sheep, cattle or goats contract fluke without any previous history or change in environment it’s possible you may have a different snail acting as the intermediate host. Keep an eye out for it.