Managing fungicide resistance in Australia viticulture

Summary

Objective

The overall aim of this work is to improve our knowledge on the mechanisms of chemical resistance by fungal pathogens to provide strategies for management of resistance in the vineyard.

Background

Botrytis bunch rot, powdery mildew and downy mildew are the top three diseases in Australian vineyards, with high economic impact from management costs and reduced income. Development of resistance to the chemicals commonly used to control them is widespread and results in failure of spray programs to manage disease. Gaps in our current knowledge include the fitness penalties associated with resistant populations, baseline levels of resistance to new fungicides, the basis of differences in product efficacy in the presence of the resistant allele and methods for in-field detection of pathogens and resistant populations in real time.

Research approach

Experiments on powdery mildew include determining the differences in resistance to various chemicals in the DMI class and the relative efficacy of those products in the face of resistance, and determination of fungicide resistance levels to other chemical classes. The feasibility of in-field real-time detection of pathogens and resistant populations is being evaluated using spore trapping technologies. Additional research on downy mildew includes determination of the extent and nature of resistance to various chemistries. Developing an understanding of movement of pathogen populations between and within vineyards is another key component of the project.

Sector benefits

This project will provide an improved understanding of the relationship between laboratory results, resistance allele frequency and the field efficacy of fungicides. Grapegrowers in premium Australian grapegrowing regions who have experienced losses from fungicide resistance will be provided with information on improved ways to manage resistance.