Friday, 24 November 2017 07:55

Heading off flystrike resistance

Written by  Paul McKee
Paul McKee says the prospect of flystrike resistance is becoming a reality. Paul McKee says the prospect of flystrike resistance is becoming a reality.

The prospect of having to manage fly populations resistant to poisons is becoming a reality for more New Zealand farmers.

If we do not change the way we use chemicals we can expect the costs of fly-strike to rise markedly.  One critical strategy will be to make it more difficult for flies to develop resistance to treatments. The best way to do this by applying chemicals correctly and at recommended rates.

In other words, there is always a cost when taking shortcuts to save a few cents in volumes of chemical used or seconds to apply the product.  

Farmers can also change from relying on single active treatments to innovative combination treatments designed to slow the development of chemical resistance.

As recommended in controlling parasitic worms, exposing flies to simultaneous treatments of different actives will make it harder for them to develop resistance.

Ravensdown has worked with a NZ company to develop two combination products to protect against flystrike and reduce the development of fly resistance.  

First, Saturate Gold is a dip concentrate combining the long acting insect growth regulators (IGR)cyromazine and diflubenzuron. It is for use in showers and jetting units on sheep up to six weeks off shears, providing up to 12 weeks protection from fly strike. 

This product is recommended for summer fly strike prevention.  With the inclusion of diflubenzuron farmers also get the extra benefit of long term lice control (something that cyromazine or dicyclanil cannot do).

Second, Fleeceguard is a water-based pour-on that combines the actions of an IGR (diflubenzuron) and synthetic pyrethroid (deltamethrin) to provide up to 14 weeks protection from flystrike. Both actives also kill lice. 

This product can be applied to sheep immediately off shears and up to six weeks of wool growth. The inclusion of deltamethrin provides a rapid knock-down for fly and lice compared to IGR-only pour-ons.  Also, its short (seven days) meat withholding period gives farmers more options with their stock.  

To get the full benefits of combination products, the best time to start using them is when no resistant fly populations exist on your farm.

Developing an integrated flystrike management programme will lead to improved animal health and farm profitability.

• Paul McKee is an animal health technical manager for Ravensdown


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