Turning off the water shoot

There is a consensus among Marlborough’s grape growers that water shoot canes produce less fruitful shoots in the following season, says Kristy Marsden. But her industry research project is the first known study into the fruitfulness of shoots arising from water shoot canes in comparison to count shoot canes. “If high yields are important, it is sensible to avoid wrapping down water shoot canes at pruning in Marlborough Sauvignon Blanc,” Kristy concludes in her report.

Kristy completed her Nelson Marlborough Institute of Technology (NMIT) Bachelor of Viticulture and Winemaking this winter, having completed and presented her industry research paper, Wrapping down water shoots at pruning in Marlborough Sauvignon Blanc: the effect on fruitfulness in the following season. The study found that yield from water shoot canes was significantly lower than that from count shoot canes, due to the mean number of bunches per shoot being significantly lower and the internode length being significantly greater, meaning less buds on the wire for water shoot canes versus count shoot canes of a similar length. “No significant difference between the two treatments was found in cane diameter, per cent budburst, bunch weight, berry weight or maturity at harvest as measured by Brix, pH and TA (total acidity),” says the report.

When it came to choosing a research project last year, Kristy looked towards pruning and the challenges carried with Covid-19. “I was thinking about labour shortages and ways to make pruning more efficient,” she says. The project questioned whether it was necessary to spend extra time training pruners to identify water shoots. The research began, with the help of Wither Hills, in autumn 2020, with 24 Sauvignon Blanc vines trained to a vertical shoot positioned trellis, with two count shoot canes and two water shoot canes wrapped down per vine. In November, budburst and node numbers were assessed, and at harvest in March 2021, yield and bunch numbers per cane were assessed.

Kristy concedes it was a small study carried out in one subregion over one year and hopes the research project will be continued in different subregions of Marlborough over a number of years. Meanwhile, Covid challenges have seen the graduate return to her pre-study career of physiotherapy. But she has no regrets about undertaking the degree programme, which she spread over five years, learning about the wine industry in the classroom, wineries, vineyards, cellar doors and as an associate wine judge at the New World Wine Awards. “It’s helpful because I do vocational physiotherapy, so I am quite often working with people in the industry,” she says. “It’s definitely something I am really glad that I have done.” It was also an opportunity to meet “so many interesting and lovely people”, she adds. “I’m sure I’ll do another vintage at some stage, maybe when we are able to travel again.”

Stewart Field, who is a viticulture lecturer and researcher at NMIT, says Kristy completed “a high-quality piece of work, that is “especially relevant to the industry after last season’s low yields experienced across Marlborough”. He says the experience gained by the students doing research projects, from the knowledge gained to the interaction with industry participants, “is a fantastic aspect to their learning journey”. And he hopes the majority of student projects provide valuable information directly to the companies supporting the research. “This knowledge should also disseminate out into the industry, providing a greater depth of knowledge, specifically in the Marlborough context, that will help management decisions in the local vineyards or wineries.”