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Victoria worms, flies and lice update - February 2019

Hamilton: Andrew Whale, Livestock Logic (a.whale@livestocklogic.com.au)

Livestock Logic Key Recommendations:

  • Continue to closely monitor weaners on pasture.
  • Conduct worm egg counts in ewes and rams if soon to be joined.
  • Drench weaners into containment zones to ensure worm burdens remain low.
  • Producers can take advantage of high worm egg counts in weaner mobs to conduct a drench resistance trial if one has not been done on the property in the last 3 years.

Over the past four weeks, conditions have generally been dry and mild, with some sporadic rain events keeping moisture present in some parts of the region. Mild conditions will reduce environmental worm kill rates on pasture, as will continued moisture, so continued monitoring is critical. Keep a close eye on stock grazing paddocks where short green pick is coming through after rain as this is often where stock will pick up high larval burdens that lead to spikes in worm egg count results 2–3 weeks post-rain. Rain will also further degrade any dry standing feed, so feed testing is important if you are relying on dry pasture for nutritional intake.

Worm challenge on pastures has generally declined over the past four weeks, but sporadic rain events will lead to isolated spikes of worm activity in areas that have received more than 15 mm. Coming into March, we anticipate spikes in young sheep needing a drench, especially those on short green pick.

As expected, worm egg count results have plateaued since January, and the majority of mature ewes and wethers have not needed drenching coming into February. Weaners and hoggets remain at higher risk and require close monitoring, especially 2–3 weeks after rain events.

Fly risk, in general, is low–moderate and without further rain should remain so for the rest of the summer.


Graph 1. Percentage of sheep needing drenching February 2019.
Graph 1. Percentage of sheep needing drenching February 2019.