Victoria worms, flies and lice update - March 2019

Hamilton: Andrew Whale, Livestock Logic (a.whale@livestocklogic.com.au) and Lexie Leonard, Livestock Logic (l.leonard@livestocklogic.com.au)

Key points

• Worm egg count adult mobs 6–8 weeks after the Autumn break (>25 mm rain)
• Worm egg count weaners/hoggets 4 weeks after the break or after letting any stock out of containment
• If you are concerned about the effectiveness of your summer worm management, formulate a plan now for the rest of the year. This will help decrease production loss in mobs later in the year.

So far, March has been slightly warmer and drier than the long term average. Following on from a relatively mild February in which there were no long drawn-out hot and dry periods, worm populations have remained present on pasture coming into autumn. This has been reflected in worm egg count (WEC) results that showed an increased number of mature aged mobs requiring drenching in March compared to February. As the weather cools down and hopefully more rain arrives, we do not expect pasture worm levels to decrease going forward, so reducing worm egg count levels in sheep now is critical to keeping pasture contamination levels low.

Now is the time to check mobs that haven’t been monitored since the New Year to ensure they are not putting high levels of worm egg contamination onto the pastures. Any pasture contamination happening now will lead to high worm burdens in sheep over winter and spring.

Barber’s pole worms are still active in many areas around Hamilton, and these infections warrant more frequent monitoring of stock as WEC levels can rise rapidly in 2–3 weeks, potentially causing production loss and death in mobs.

Ensuring you are using an effective drench is critical to maintaining drench efficacy on your property; we advise always using a proven effective combination drench when drenching any mob, and at this time of year including the most potent products such as Zolvix^®, Startect^®, and naphthalophos combinations to ensure no resistant worms survive through to the rest of the year.

With the recent rain, we are starting to see green pick coming back in paddocks that have been locked up, and we expect the pasture worm challenge to be moderate–high in paddocks that have held feed at greater than 1200 kilogram dry matter over summer. Keep this in mind for set-stocked mobs or when letting stock out of containment zones onto short green pick.