Powdery mildew is caused by the fungal pathogen Uncinula necator. It is the most persistent fungal problem of grapes in WA and one of the most widespread fungal diseases of grapevines in the world. It is characterised by ash-grey to white powdery growth on green tissue of the vine. If uncontrolled it can cause serious crop losses and impair wine quality.https://researchlibrary.agric.wa.gov.au/bulletins/1076/thumbnail.jp
