SHEEP producers were this week warned to rotate fly chemical usage and follow label instructions as the first reports of flystrike come in.
After a New South Wales report of suspected fly resistance to the chemicals cyromazine and dicyclanil, at a Department of Primary Industries flystrike workshop at Coleraine DPI sheep medicine project leader Robert Suter said if farmers believed they had any issues with fly control chemicals they should contact the chemical company.
Producers could also contact the Australian Pesticides and Veterinary Medicines Authority to report any unintended effect from the use of registered agricultural or veterinary chemicals, he said.
Dr Suter said the New South Wales case was the only report of resistance as a factor in reduced protection. Other cases involved wash-out from excess rain and sometimes poor application.
As with internal parasite treatments, Dr Suter advised farmers to rotate their fly control chemicals.
“We have a vast array of chemical types available for fly control and we also must remember that we are treating sheep for lice with a similar array of chemicals.
“So think about everything you treat your wool with and try to alternate between products,” he said.
“We have two long-acting products for fly control which are different chemical classes and rather than use the same one every year it is probably more appropriate to alternate between them.
“At other times of the year when you probably don’t need that long length of protection period go and pick one of the other products that provides an alternate chemical mechanism but sufficient protection.”
Novartis western Victoria territory manager Luke Drechsler told farmers at the workshop to ensure they use the company’s fly control products Clik (dicyclanil) and Vetrazin (cyromazine) strictly to label directions.
He said he had received three calls in the last week of mulesed sheep being struck after using Clik and the pain relief gel Tri Solfen together.
Farmers at the DPI workshop said they had used Bayer Australia’s Tri-Solfen on the mulesing wound, applying Clik in the wool around the wound. However, Mr Drechsler said Clik needed to be applied “right across the wound”. The Clik label advises treating the mulesing wound and the surrounding 25 millimetres of wool. Novartis advises not to use Vetrazin on open wounds.
New South Wales mulesing contractor Gordon Godson said he had always used Tri Solfen first to limit the discomfort of mulesing, before applying Clik across the wound and in the wool around the edge of mulesing cut.
“We have done that on many thousands of sheep and we have never had any fly problems.”
Tri-Solfen inventor Meredith Shiel said based on early trial work, the Tri-Solfen should be applied to the wound first before the Clik was applied.
Although there has been no research on how Clik and Tr-Solfen might interact, Bayer Australia livestock field veterinarian Neil Cooper said the agreed method with Novartis was that the pain relief treatment should applied before the fly chemical.
“Field experience has shown that is how it should be done.”
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