Wine Industry Newsletter

Manipulating bunch architecture to manage rot

Sour rot on a bunch of Chenin Blanc wine grapes
A new research project will begin this season lead by DPIRD research officer Andrew Taylor, seeking to answer the question ‘Can post flowering harvester applications reduce bunch rot risk and manipulate bunch architecture in Western Australia?’.

Bunch rots are a significant cost to the profitability of WA wine production due to direct losses of fruit, harvest downgrades and the costs associated with their control. Further pressure has occurred with the recent changes to iprodione use and export markets moving towards a requirement for fewer pesticide applications. Successful use of a post flowering harvester treatment would provide a pesticide free approach to bunch rot management.

Reducing bunch compaction is considered the holy grail of bunch rot management but this is not easy to achieve on mature vineyards. Use of harvesters to remove bunch trash after flowering has minimised bunch rots under New Zealand conditions and reduced compaction. It is unknown whether the same result will occur in WA due to differences in climatic conditions.

This project will investigate the use of harvesters, post flowering, and the impact it has on the bunch architecture and bunch rot incidence in different WA growing regions to account for weather differences. The experiment will be conducted on three cultivars, Chardonnay, Semillon and Chenin Blanc to account for any potential varietal differences that may occur. Each block will investigate different beater speeds of the harvester and the impact that this may have on harvest yield and bunch architecture. Assessments at harvest will include disease incidence and severity, bunch size, weight and compaction.

This project is funded via the Wine Australia Incubator Initiative. Progress of the project will be captured in future WIN editions and for more information contact Andrew at