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Tasmania worms, flies and lice update - November 2020

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Western Australia worms, flies and lice update - November 2020

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

The countryside has dried considerably in the last month: little rain and a few days with enough wind to run at least two windmills. Irrigators are going flat-out. Nevertheless, some places in the hard-bitten country between Bothwell and Ouse have more feed than I’ve seen in 30 years in Tasmania. That good!

What causes worms to drop off in spring (later here than in western Victoria, but drop off they do)? Firstly, there is the dilution effect. Sheep grazing 3000 kg green dry matter (GDM) take in less larvae than those grazing 700 kg GDM as they do during winter. Secondly, the better nutrition helps lactating ewes restore immunity. Thirdly, Merino weaners (children may well ask what they are) develop immunity for the first time, so the sheep that have capacity to pox paddocks to the top wire no longer do so. Finally, and most importantly, warmth and moisture activate larvae so they burn their energy supplies and die, rather than lying around indefinitely as they do during the winter.

Here in li’l ole Tasmania we don’t get the environmental decontamination that they do at Hamilton or places north of the ranges in Victoria. What’s the importance? Simply, that the summer drenches are still the best way to reduce contamination going forward into autumn and winter. If you hit the worm population when it is low, you get benefit in the following months.

All weaners need a drench. Ewes staying on permanent pastures or paddocks to be grazed by lambs later in the year should be drenched. Only the fat, prodigiously ugly, crossbred ewes going onto Jenny Craig paddocks, or Merino ewes being sent bush, can do without.

Many areas in Tasmania do not need two summer drenches. South of Campbell Town the summers make a second drench unnecessary, and perhaps counterproductive because drenching when the paddocks look like the Gobi Desert promotes drench resistance. This year is different. Nearly all sheep will need a second drench if they are on perennial pastures.

Fluke: A client found fluke in a mob of ewes grazing a paddock with a swampy creek through it. It is likely that ewes carried infection through the winter, rather than early pickup, but that is unknown. The point is, that after a prodigiously wet winter and spring, fluke habitat may well expand to areas where they have not been previously or occur occasionally. The swampy margins of the lower South Esk and Macquarie are the classic ‘sometimes’ fluke areas.

However, semi-permanent creeks, particularly those that have upstream dams, have been and will continue to flow well into summer. These creeks can be a trap. The good news is that the flukey bush runs in the high country may not be as bad this year, because sheep and cattle will find adequate grazing away from the swamps, soaks and springs.

Acknowledgement: November 2020 marks 30 years in Tasmania for family Nilon. To my many loyal clients in all parts of the State thank you for your loyalty and for what you have taught me over the journey.

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