Tasmania worms, flies and lice update - April 2020

St Paul's Dome, Avoca Tasmania.

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

No need to tell the regulars that there has been enough rain to make for one of the best autumns of recent times.  Launceston airport received over 100 mm in March and at the time of writing was well over 100 mm for April. All areas have received substantial falls with the possible exception of the western side of the plateau and the very top of the Derwent drainage.

It will come as no surprise that WECs in young sheep are really on the move.  Counts from Merino weaners have triggered drenching, and meat lambs on grass are also under threat.  Second-year irrigated grass paddocks are rocking with worms. There was one report of a breakdown on an irrigated clover paddock, which is a bit rare (count of 1200 epg). 

Most adult sheep are fine. Crossbred ewes are blowing out like a surfacing whale and Merinos in the drier areas are out of the drought-lots and enjoying at least 700 kg green dry matter/ha.

So, monitor proactively or drench to a routine. No point having to drench after every WEC.  If that’s happening you are not monitoring frequently enough. Also, remember to record your results against the paddock. That way you can assess contamination in the run up to lambing.

It ain’t necessarily so:  Advisers and extension people operate on paradigms. These may well be based on good science, but it’s important to realise that general recommendations derive from mostly homogenous climatic and production systems. So, WormKill, Worm Plan, Worm anything make assumptions about how your farm runs, and the blind application of a generic recommendation may result in a disaster. Here’s a cupla examples:

• Irrigation has revolutionised lamb finishing, but none of the circulated worm programs work under pivots. Strategic drenches have no effect because irrigated paddocks (particularly grass) are endlessly cool and green. Grazing with cattle or spelling in the spring for seed harvesting or fodder conservation helps a bit.  Rotational grazing does nothing because rotation lengths are too short. Beware!
• The second example relates to the bush runs and semi-improved country on the central plateau. Wethers on these runs struggle through winter on fresh air and saggs* and stagger to the shed for a spring shearing. You would think that the low stocking rates would mean few worms. Experience suggests otherwise. So, the strategic drench is given well after Christmas and these sheep often need to be under the protection of an long acting product to survive the winter.

*for the non-Taswegians: saggs are a tussocky plant, Lomandra longifolia.