Improving the productivity of Tasmanian vineyards

The prediction and regulation of grapevine yield is a common goal for growers, viticulturists, winemakers, and sales teams alike. The inability to accurately forecast and regulate yield has substantial economic consequences relating to pre-harvest crop reduction, harvest planning, price negotiations, intake scheduling, tank space allocation, capital investment and development of marketing strategies. The challenge of fluctuating grapevine yields appears to be exacerbated in cool climate production regions such as Tasmania.

Improved understanding of the key drivers of vine productivity will lead to improved management of vineyards, and hence the ability to achieve more consistent yields. Pruning and vine nutrition are two costly vineyard practices which have the ability to influence the productivity of vines and hence impact on yields and quality. The impact of climate and site are often thought to override the impact of pruning and vine nutrition in the vineyard.

This project set out to gather data to inform decisions about bud fruitfulness management, pruning and nutrition management. Three themed trials were established to allow three seasons of investigation in these areas. A fourth theme was developed to monitor industry awareness, and practice change.

Results presented here build understanding about the primary drivers of fruitfulness and confirm that predicting fruitfulness in cool climates remains challenging. Results in the vine nutrition theme suggest that current growers practise is appropriate for balanced vine growth for production of current yield and quality targets. Additional nitrogen may result in improved juice YAN which would be beneficial in challenging seasons. Results in the pruning theme highlight that mechanical pruning did not result in reduced yields or vine productivity, and could be considered to lead to significant cost savings for large vineyards or grower consortiums. The decision between spur and cane pruning needs to consider the variability in cane health and availability of skilled pruning labour, but with all things being equal, there were not major differences under the two systems.

These research findings can be complemented by industry engagement and extension provided by Wine Tasmania. Peer to peer learning between growers and collaborative training around conducting on-farm trials will be a significant achievement of this project.