Putting berry shrivel under the microscope
One of the busiest people in the Balnaves vineyards in Coonawarra this coming vintage won’t be tending vines or picking fruit – at least not in a conventional way.
Dr Vinay Pagay will be measuring and analysing what is going on in and around the vines, from light levels and plant water status to canopy and bunch temperature and berry composition.
Some of it will involve old-fashioned techniques and basic observation (albeit with an educated eye), but he will also call in modern technology such as fluorescence microscopy and impedance spectroscopy. Both will help measure berry health.
The aim is to find out as much as possible about the environmental factors that may be the cause of berry shrivel in Cabernet Sauvignon, and the impact that varying degrees of shrivel have on yields and wine quality.
To date quite a bit of work has been done with Shiraz, but Shiraz is known to be different to the norm in a number of ways. Not surprisingly, Limestone Coast growers are keen to get some specific information about Cabernet and proposed a project for possible funding under Wine Australia’s Incubator Initiative.
Dr Pagay, who is a researcher at the University of Adelaide, saw it as a nice extension of his current work in the region looking at the effect of heatwaves on vine performance and put up his hand. However, he confesses that he sees the one-year project setting up a PhD topic for someone interested in really getting to the bottom of a complex issue with global ramifications.
Berry shrivel is known to affect quality and decrease yields (by as much as 30 per cent in bad years) but we still don’t fully understand the causes, and therefore don’t know what to suggest growers do to mitigate their risks.
Dr Pagay is currently gearing up for what will an intensive period once veraison begins in the Coonawarra in late January. He has been working closely with Treasury Wine Estates, as well as Balnaves, which is giving him access to two vineyards.
‘We will sample berries every two weeks for a month and a half, making a range of measurements, then at harvest we will analyse the yield and make some trial wines so we can look at colour and polyphenols and sensory aspects’, he said.
‘We will go right to the end of the project with the data collection, then analytical chemistry with the wine and informal sensory testing. The wine will be very new, but we need the sensory aspects to get a feel for how consumers might respond.’
An important component of the project is to try to determine what impact different levels of berry shrivel have. ‘Ultimately we want to help winemakers make decisions about what level is acceptable for quality. If we discover that 10 per cent doesn’t do anything to the wine then 10 per cent is an acceptable level; but maybe 25 per cent is not.’
Dr Pagay completed a PhD in viticulture and engineering at Cornell University in the USA before moving to Adelaide at the start of 2015. He lectures in both viticulture and vineyard engineering (a new area at the University of Adelaide) and his research focus is on grapevine physiology.
His engineering background gives him expertise in developing sensors for use in vineyards but he is interested in any approach that can improve vineyard performance, particularly around irrigation management.
‘Broadly I am trying to understand how the environment influences vines, whether they are wine or table grape vines’, he said. ‘A lot of what I do is in the optimisation in vineyards; how do we use resources such as water better.’