The prospect of having to manage fly populations resistant to chemical treatments is becoming a reality for an increasing number of New Zealand farmers. Without making changes to the way in which we have been using chemicals, we can expect the future costs of fly strike to significantly increase.

One critical strategy will be to make it increasingly difficult for flies to develop resistance to treatments. This is best achieved by farmers ensuring chemicals are always applied correctly and at the recommended rates. In other words, there is always a cost when taking short cuts to save a few cents in volumes of chemical used or seconds in application of product.

In addition to the correct application of chemicals, farmers can also change from relying on single active treatments to innovative combination treatments designed to slow the development of chemical resistance. As has been recommended with controlling parasitic worms, exposing flies to simultaneous treatments of different actives will make it harder for resistance to be developed.

Ravensdown has worked with a New Zealand company to develop two unique combination products that are designed to provide both effective flystrike protection and reduce the development of fly resistance.

1. Saturate® Gold is a unique dip concentrate combining the long acting insect growth regulators (IGR’s) 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. Ravensdown recommends Saturate Gold for summer fly strike prevention programme's. With the inclusion of diflubenzuron farmers also get the additional benefit of long term lice control (something that cyromazine or dicyclanil cannot do).
2. Fleeceguard® is a unique 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 provide control of lice. Fleeceguard 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 on’s. An added feature of Fleeceguard is a really short meat withholding period of seven days that also gives farmers more options with their stock.

To achieve the full benefits from using 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. This summer, talk with your Ravensdown Animal Health Technical Manager for more information on improving your fly strike prevention programme.