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Tasmania worms, flies and lice update - April 2021

Tasmania WormBoss Worm Control Programs

Tasmania WormBoss Drench Decision Guides

Sheep

Goats

Sheep

Goats

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

The colossal rain that hit NSW in late March had largely petered out by the time it reached Tasmania. The northeast, east coast and parts of the lower midlands got a helpful rain, most other areas it was more promise than delivery (maybe we should call it a COVID Vaccine rain)! It has been a bit cooler. Many sheep areas have had a few light to goodish frosts and even some snow in the higher areas.

Climatic conditions are ideal for worms. Perennial pastures never got the chance to decontaminate, and irrigated paddocks (particularly second year rye grass paddocks) are starting to break down. So:

  • Merino weaners on perennial pastures are at high risk. Drench at a trigger of 300 eggs per gram (epg).
  • Crossbred lambs on irrigated paddocks (with the possible exception of brassicas) are likely to be facing some challenge. Monitor diligently and drench at about 200 epg.
  • Our barber’s pole season is blessedly short. Cold and frosts will slow and eventually stop development of eggs to larvae, but be aware that irrigated paddocks in the north of the state may be carrying considerable barber’s pole contamination. You should get larval cultures done to check for their presence. While they may be a new feature of your enterprise, do not assume that they will be susceptible to all drenches. Chances are they have been in your system for many years without being noticeable as a separate entity. Therefore, these worms may already be resistant to the drenches you have been using. If you find barber’s pole, consult your adviser.

Autumn lambing is not highly regarded in Tas and far from common. However, some of the croppers in the north of the state have serious spring droughts when grazing is removed to allow crop planting. These guys lamb in autumn and wean before cropping takes country away. The lambs stay on remaining pasture while the ewes are sent to ‘Jenny Craig’ paddocks, whether they need it or not.

Autumn/winter lambing ewes are at greater risk of worms than their spring lambing cohorts. Peak lactation coincides with limited tucker at a time when larval survival and availability is excellent. Wet winters produce some calamities.

As with spring lambers I recommend a risk assessment approach. It’s unknown to recommend no pre-lambing drench. Most years a short-acting will suffice. However, some years mandate a prolonged acting treatment for autumn lambers. Dry autumns where body condition score has fallen away, followed by a wet winter, can produce a worm factory. Those years may require treating with a long-acting.

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