The Australian Wine Research Institute

Improving the consistency of description and measurement of disease

Project summary

Robust, quantitative identification of the type and extent of grape disease found in the vineyard can be problematic. Producers have limited opportunity to screen and identify affected grapes in order to stream batches and/or inform purchasing/pricing decisions. Although most contracts for grape supply have a clause on minimum disease levels, assessment of the degree of infection is often done visually, with a degree of subjectivity. This project will seek to establish objective benchmarks for grape disease, e.g. an industry-wide definition of what is meant by the term ‘2% bunch rot’, and use those objective benchmarks to develop analytical tools to measure grape disease. DNA and chemical markers exist for fungal diseases, but current methods are not cost effective and are difficult to apply in a timely fashion. Rapid methods have been partially examined previously, but further work must be conducted to provide a simple, practical tool for in-field analysis. In addition to fruit diseases such as Powdery Mildew and Botrytis, rapid methods might ultimately be applicable to other economically important vine diseases, such as Eutypa, to provide early diagnosis. The project will also evaluate the impact of benchmarked disease ratings on wine style by making wines from grapes with, for example, 2%, 4%, 6%, 10% and 15% bunch rot, across several major varietals.