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Tasmania worms, flies and lice update - February 2019

Tasmania WormBoss Worm Control Programs

Tasmania WormBoss Drench Decision Guides





Perth: Paul Nilon, Nilon Farm Health (

Since the last missive, large areas of Tasmania have been burnt, but thankfully with almost no stock losses or serious consequences for producers. Unfortunately, there was massive damage to forestry and tourist infrastructure.

In the last 10 days, many areas got 25–50 mm of rain. This steadied the fires, and in all likelihood would have activated the worms.

Worm egg counts (WECs) have been all over the place. Many mobs of Merino weaners have returned moderate to high counts (greater than 500 eggs per gram (epg)). Adult Merinos are mostly OK (reflecting good body condition and the hot, dry summer since mid-December). Crossbred (XB) ewes are robust, as they should be, except for the mob of fat-as-seals ewes that had 900 epg and fluke! Finishing lambs are mostly good on legumes, but variable on grass. So, the suggestions are:

  • Get ready to give all Merinos on perennial pastures their second summer drench. Because we had such a long spring, the usual recommendation that areas south of Campbelltown do not need a second summer drench is void. Therefore, give a second summer drench unless there is compelling evidence from WECs that it’s not necessary.
  • Most mobs of XB ewes are OK, but beware of the possibility of Haemonchus infections in the northern irrigation areas.
  • Drench XB lambs to the usual trigger.

Some Warnings: As a footnote last month I warned of the likelihood of Haemonchus on some irrigated places in the Westbury/Longford/Cressy area. Since then, Haemonchus has been confirmed on two of the suspect places, on another three, and with larval differentiations pending on one more. We’ve not seen huge losses (one property lost a few lambs, and another noticed a few with bottle jaw): the suspicion about high counts (1000–3000 epg) without the scouring or production loss, is that such a count would be due to barber’s pole worms. Make sure you monitor, with or without signs of scouring.

Because the spring was cool, followed by six weeks of hot, windy weather, flies have not been a big issue. The rain and humid weather of the last few weeks are much more favourable for fly activity, and I have seen a few strike cases in intensively monitored flocks in the north. Untreated sheep or mobs whose protection is running out may need another dose. Choose a shorter acting product from a different chemical group to the one used at the start of summer. Be mindful of all withholds, particularly in finishing lambs.

Finally, I mentioned a fluke finding in a routine WEC. Fact is that irrigation is expanding our fluke habitat. If you have irrigation drains returning water to semipermanent creeks you are at risk. Do some fluke tests on mobs that have grazed the drains and creeks. Repeat them in the autumn.

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