When a local grower wanted to make a change to his vineyard management strategy, he turned to Brock University’s Cool Climate Oenology and Viticulture Institute (CCOVI) for help.

Fast forward five years and that grower is now combining his expertise with CCOVI’s research to help guide the decisions he makes in the vineyard.

CCOVI Director Debbie Inglis, alongside CCOVI Scientist Belinda Kemp and Assistant Professor in Biological Sciences Jim Willwerth, recently completed a study on the impact that different grapevine leaf removal treatments have on Cabernet Franc and Pinot noir grapes and wine.

Malcolm Lawrie, who owns the Niagara-on-the-Lake vineyard where the research took place, has now implemented CCOVI’s findings into the canopy management strategy used for his sparkling wine grapes.

“For me, the trial is about helping growers see whether the practices in the field, when tested in a lab, are working the way they think,” he says. “It’s a challenge getting consistency in quality with annual weather variation and this type of research enables growers to better understand the effects of different techniques. It’s really fascinating.”

Leaf removal exposes the grapes to more sunlight, can help improve air circulation and the penetration of fungicides and insecticides, and improve flavour compounds, colour and bud fertility. In cool climate regions, removal of leaves in the fruit zone of the vine has also been shown to decrease disease and improve grape and wine flavour.

Before CCOVI’s study, however, there was limited research that examined the impact of leaf removal on sparkling wine, something that was requested specifically by the local grape and wine industry. Many Canadian grape growers have also invested in mechanical leaf removal equipment in recent years, making the comparison between mechanical and by-hand removal another important component of the research.

A total of seven leaf removal treatments and one control (where no leaves were removed) were investigated in the vineyard during the study. Researchers then examined the impact that the timing, severity and method of removal had on the chemical and sensory differences exhibited in the wines made from those grapes.

The study found that hand-removing 33 per cent of the leaves throughout the grapevine canopy when the grapes begin to form into clusters (known as bunch closure) provided the most benefit to Lawrie’s sparkling wine grapes. By removing about a third of the vine’s leaves, the treatment allowed for photosynthesis to still ripen the grapes, while also minimizing the presence of certain phenolic compounds that are less desirable in sparkling wine. The result is a healthy and productive vine that produces grapes which are perfectly suited for sparkling wine.

Matthias Oppenlaender, who manages the Lawrie vineyard as the CEO of Huebel Grapes Estates, says the project has shown promising results so far.

“CCOVI’s ongoing research and support of Ontario’s grape growers and winemakers is essential for the health and sustainability of the industry by driving forward wine quality, competitiveness and innovation,” he says.

Kemp says the research will help grape growers tailor their grapevine canopy management strategy to each particular type of grape and wine style rather than taking a one-size-fits-all approach. She also says the research benefits the entire grape and wine value chain, from the growers in the vineyard to those making the final wine.

“I’m so pleased that we did this work because it was such a wonderful collaboration and example of how applied scientific research has a direct impact on the research priorities of the grape and wine industry across Ontario,” says Kemp. “That’s what we’re here to do at CCOVI.”

This research is part of a larger project, ‘Adaptation and Innovation: An integrative research program to improve grapevine health, wine quality, competitiveness and sustainability of the Canadian wine grape industry.’ It is supported by a Natural Sciences and Engineering Research Council of Canada (NSERC) Collaborative Research and Development (CRD) Grant, Ontario Grape & Wine Research Inc (OGWRI), as well as in-kind contributions from industry partners.

Updates about the study’s progression has been shared with the industry in presentations and tastings at conferences and meetings across Ontario, as well as in CCOVI’s Lecture Series and the popular Fizz Club.

A formal research paper is forthcoming.