Spring

"Recorded September 2019 at Bud Burst. James and Gill discuss their predictions for the coming vintage. What is similar to last spring? We have a pretty similar climate forecast. A positive Indian Ocean Dipole (IOD) remains the main driver of Australia's climate over the coming months. In lay terms the low-pressure fronts coming from the Indian Ocean are going further south than typical. A positive IOD is typically associated with below average rainfall and warmer than average days for large parts of southern and central Australia. A drier than average end to the year is likely. Spring days are likely to be warmer than average. With below average rainfall forecast and therefore clearer skies, nights are likely to be cooler than average in parts of the south at times, with increased risk of frost in susceptible areas. What is different to this time last year? Rainfall in May and June which helped fill up soil moisture in our topsoil. For vintage 2019 we started a bit short of soil moisture – we called it a ‘green drought’ – but at least this Vintage we start with a full soil profile. What might happen this Vintage? The prediction is for a warmer and drier spring season than average. If this prediction occurs it has some short-term benefits for vineyards, but also some long-term consequences. In the short term, a warm and dry spring weather reduces fungal disease pressure. A dry spring greatly reduces the chances of an outbreak of Downy Mildew, and the rate of Powdery Mildew spread, increased by humidity or suppressed by uV light, is also reduced making it much easier to keep up protection. The risks of Botrytis are also reduced if the weather during flowering (mid to late November) is warm and dry. Over the longer term it puts pressure on our irrigation resources – some sites will need to irrigate early in summer, which then has flow on effects on the amounts of water available for harvest, especially if we have heatwaves again. "