Downy mildew infection events in Western Australian viticulture regions

Abstract

Downy mildew infection events in Western Australian viticulture regions

Summary

The first component of this project was to use historic weather data to identify the risk of downy mildew infection in grape growing regions of Western Australia and the months when infection was most likely. Two climatic models were used, examining both long-term average weather data and using real daily climatic data from 1990 until 2001. The Margaret River region was identified as having an extreme risk of downy infection, the Pemberton region had a high risk and the Albany region had a medium risk of downy mildew infection. All other wine growing regions in the state had a low or negligible risk of downy mildew infection.

The second component of this project was to investigate the feasibility of the Bureau of Meteorology (BOM) using real time climatic data to predict the likelihood of both primary and secondary infection events in the next 24 hours. In the 2003/04 season the accuracy of the predictions from the BOM were verified using weather station data collected in the Margaret River and Manjimup regions.

Verification, and if necessary modification of the BOM predictive model will continue in 2004/05. If the BOM model can accurately predict downy mildew weather events, then a downy mildew page will be created on the BOM web site with the prediction for the next 24 hours. If an infection event is very likely (about 80% chance) then a downy mildew weather alert will be issued to the press. This information can then be used by growers to plan strategic applications of pre and post infection fungicides. The service may also be expanded to include other regions in Western Australia.