Stroby Resistance - UPDATE 30/8/2012

Powdery mildew strains resistant to the strobilurin fungicides (Group 11 fungicides - Amistar, Cabrio and Flint) have  been confirmed in vineyards in South Australia, Victoria and Western Australia in the last 12 months. Testing of samples of powdery mildew in these vineyards confirmed a high level of the resistant gene – which prevents  the strobilurin fungicide being effective. 

Flint is a group 11 fungicide.
The development of these recent strains signal the need for a different approach to using these products on  grapes in Australia. 

News about stroby resistance in Australia has been slow to be made available to the grape and wine industry. There have been changes to the resistance management guidelines but is this enough to raise awareness? We think this is one of the most significant developments in the last ten years. Do you know about it?

In Europe and parts of the USA where strobilurins have been used for a longer time, resistant strains of both powdery mildew and downy mildew have been causing crop losses in vineyards since the early 2000s. To make matters worse once stroby resistance develops it is permanent.

Grape growers need to ask question about stroby resistance and how it might affect their disease control. If the wine industry waits to be lead by chemical distributors and resellers - the spread of information will be very slow.