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Tasmania worms, flies and lice update - November 2017

Tasmania WormBoss Worm Control Programs

Tasmania WormBoss Drench Decision Guides





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

The dry weather continues. Fronts and troughs that have brought storms to other parts seem to have an objection to passing over Tasmania. Rain promised in the second week of November fizzled out. The Fingal Valley and East Coast are absolutely desperate. In other areas the spring is starting to wane but has held on surprisingly well for what has been a dry month. The river in front of my house near Perth is at late summer levels.

There’s not much activity on the worm front. In the run up to marking few people are monitoring, which is a pity, but understandable. 

Weaning starts at the end of the month and so it’s timely to discuss the first summer drench. The first question is timing: the way the season is shaping in the midlands, Fingal and Derwent Valleys you should wean as early as possible. The green will quickly run out, and it’s a case of “no green, no grow”. It’s different if you have irrigation, but that depends on it also not running out. Be realistic about the number of suckers you will turn off. Do not delay weaning of the whole mob to cater for them. Split the weaning or do away with the suckers.

Drench choice for a weaning drench depends on a few factors: for Merino flocks in the dry areas the weaning drench is the first summer drench, and so you need to use a working drench. Notionally, 95% (kill of the existing worm burden) is a working drench. In reality this is inadequate, and you need to be as high as possible (99%). Without drench efficacy information you should rely on the new compounds or the most potent multi-actives. Ewes being sent to the Gobi desert (bush runs) do not need a first summer drench. The purpose is to keep perennial pastures cleaner for the autumn, and so sharing a few worm eggs with the bandicoots amongst the gravel and wattles is ok.

For prime lambs, the notion of a first summer drench is a bit askew. Ewes should get one if they are going back onto perennial pastures. Those sent to the bush (yes, some irrigation places still have undeveloped areas), or doing clean-up duties do not need one. Lambs going onto perennial pasture should get a summer/weaning drench, again with very high efficacy. Lambs going onto what are likely to be contaminated crop paddocks (legume and grass circles) should be drenched, but super high efficacy is not critical as these paddocks will not decontaminate so well over the summer because they are constantly green and wet. Watch the ESI (Export Slaughter Interval: the time from chemical application to when an animal is slaughtered for export) for lambs close to finishing.

Finally, somebody mentioned mature wethers to me the other day. I thought they were an eradicated life form, but numbers are increasing on the back of the wool market. If they are grazing perennial pastures they need a summer drench, and preferably in advance of weaning (simply because by the time weaning is done it’s Christmas, and in the New Year everybody is as busy as a one-armed cello player with crabs, and the risk is that the first summer drench will become an autumn break/early winter drench).

Another new formulation to mention: Clik Extra (Elanco). This is a more concentrated form of dicyclanil with a registered claim of up to 29 weeks protection (compared with 18-24 weeks for standard Clik). The first comment is that Clik standard has held up extremely well. I’ve not heard of it falling short of the 24 weeks, even in wet summers like 2011. Clik Extra will be an excellent product if you give a “first summer” fly treatment. This is the practice of treating in advance of the expected fly wave to knock some generations of multiplication off the fly population. The practice is supported by some experimental observations, and by modelling. In Tasmania, the fly waves tend to be bayside rather than oceanic, and so the need for and success of early treatment is problematic. Moreover, our fly season runs out late March (most years) so sheep treated in late spring or early summer will be well and truly protected by Clik standard. So, a good idea but probably not needed for this neck of the woods.