< Back to Outlooks Listing

Tasmania worms, flies and lice update - June 2020

Tasmania WormBoss Worm Control Programs

Tasmania WormBoss Drench Decision Guides





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

While the last month has not given buckets of rain, the ground is wet, the spuds are rotting unharvested and plantings delayed.  Most areas have had decent frosts (particularly the second week of June), but overall it has not been so cold or frosty that pasture growth has stopped.

WECs from all classes of sheep (except Merino weaners) have been low. This reflects their exceptional body condition and the pasture going forward. It’s a rare year that Merino weaners do not have worms. What is surprising is that the Nematodirus numbers have hung on well after they would normally decline. Some counts have been quite ugly: 900+ Nematodirus plus strongylids. I am guessing it is a hangover from the dry summer where the Nems were the only thing to survive and got in a couple of generations before the autumn break.

Let’s return to our perennial favourite: should we use a long acting drench? At this stage it looks like:

  • Some mobs of Merino weaners will benefit. Better they get an LA rather than be drenched and then put onto a fresh paddock. Keep the fresh paddocks for the lambing ewes and put the LA treated weaners back on to their contaminated paddocks provided they have sufficient pasture.
  • Most mobs of XB ewes will get through without an LA. Indeed, if you have good monitoring info to show little contamination it may be the year to do away with a pre-lambing drench.
  • Merino ewes will benefit from an LA if:
    • They are still light (Fingal Valley, East Coast and Derwent Valley);
    • If tucker is still short;
    • Monitoring info shows widespread contamination. The trick is to record your WECs against the paddock.

More Quarantine Issues: A client imported trade lambs with a rip-roaring fluke burden. There have been a few percent mortalities, but the big issue is that growth rates have been abysmal. It is highly unlikely that fluke will establish on the property, but ya never know!

The vendor had treated for fluke, but for whatever reason the treatment failed. Mature fluke were found 8 weeks after the drench date. That is not the point. We need to give some thought to how to prevent this:

  • Ask vendors their fluke status. If they routinely have fluke or use fluke drenches (check the vendor declaration and ask for a sheep health statement) you should treat:
    • Finishing lambs that were weaned after about 1 Nov (lambs weaned before this date are unlikely to have picked fluke up).
    • Any mob of imported ewes.
  • Be mindful that fluke habitat is expanding with irrigation. 
  • Get your agent to diligently enquire the fluke status of mainland vendors. Also keep in mind that widespread mainland drought will have pushed fluke to the back of producer’s minds. Large areas of the Tablelands/Slopes in NSW, East Gippsland and the northern draining rivers in Victoria support fluke.
  • If in doubt give a quarantine drench and, after any treatment, do a 3 week post-drenching fluke check, although keep in mind that there are no WAAVP guidelines for the detection of flukicide resistance. We do not really know the severity or distribution of triclabendazole resistance, but it is out there.

Liver fluke at Rokeby, Tasmania
Liver fluke at Rokeby, Tasmania
Liver fluke close-up
Liver fluke close-up