Grape growers and winemakers around the world will be able to easily assess powdery mildew in the field with the help of a mobile application just released globally.
PMapp, which supports decisions about grape quality, has been developed by the University of Adelaide in close collaboration with the Australian grape and wine sector, and supported by Wine Australia.
"Powdery mildew is a serious disease that affects grapevines worldwide and can cause off flavours and aromas in wine if it is not controlled," says project leader Eileen Scott, Professor of Plant Pathology at the University of Adelaide's School of Agriculture, Food and Wine.
"It's a costly disease for wine sectors across the world through loss of yield and cost of control and, because of the serious quality issues for wine, there is little tolerance of powdery mildew in the winery. But it's hard to assess - the symptoms can be hard to distinguish from dust or spray residue.
"PMapp is a simple tool that facilitates efficient assessment and recording of the severity and incidence of powdery mildew."
A local version of PMapp was released in Australia in December 2015 and proved its worth for the grape and wine community during the 2016 Australian vintage. It has now been made available to download outside Australia.
Powdery mildew is assessed in the vineyard as the percentage surface area of grape bunches affected, which gives a measure of disease severity. PMapp allows the user to visually assess the severity by matching it with computer-generated images.
The app allows assessors to enter disease data quickly in the vineyard, email the results and then analyse the resulting spreadsheet, which records GPS coordinates and other details of the assessment.
There is also a suite of online resources to support PMapp. This can be used to train or up-skill wine sector personnel and students to recognise powdery mildew symptoms and estimate disease severity.
Wine Australia's General Manager Research, Development and Extension Dr Liz Waters says that PMapp is a valuable tool for the grape and wine community. "The PMapp and training website developers have taken the findings of this comprehensive research project funded by Wine Australia and produced two useable tools for the wine sector," Dr Waters says.
Comments from Australian users over the 2015/2016 season include:
Ian Macrae, CCW Cooperative Ltd: "Although PMapp was developed for assessing the severity of powdery mildew, we used the app for bunch rot assessment as well. Accurate assessment of severity is required when the patch is facing possible rejection. PMapp was a great tool in making decisions acceptable to both grower and winery."
Andrew Weeks, Executive Director, Australian Vignerons: "PMapp offers potential for a uniform and reliable assessment procedure for powdery mildew, which in turn provides a consistent market signal for winegrowers. This may lead to better understanding of disease control, and ultimately benefits in wine."
Alex Sas, Chief Viticulturist of Accolade Wines: "PMapp will quickly become part of the standard operating procedures of large wine companies in Australia and worldwide."
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