BOTRYTIS PREVENTION
Shaking the heck out of botrytis Te s s a N i c h o l s o n
W
hen we remember vintage 2 0 1 7, we will remember weather events. Rain, lots of it, impacted on fruit quality for those who didn’t take care to manage their canopies and look after their fruit. But for those who decided to remove trash early in the season by mechanically shaking their vines, the end results yet again proved they had made the right decision. Now the question is, why aren’t more people employing the practice, especially given the stellar results that have been achieved by those who have? Mark Allen is the head of the Mechanical Shaking trials, and says the results from this year – one of the worst ever for botrytis – saw an average of 52 percent less botrytis in vines that were shaken, when compared with those that weren’t. In most cases, that meant the level of botrytis fell below the five-percent disease threshold wineries enforce. He strongly believes those
A visual representation of positive results from mechanical shaking before and after Cyclone Cook. To the left are grape bunches from the control row, and past the red line to the right grape bunches typical of shaken vines, with infected bunches in the bottom portion of each sample.
results could have been even higher, if growers had monitored closely how well the shaking was undertaken. But back to the point that baffles him most. Why aren’t more people undertaking shaking, espe-
cially growers with susceptible varieties like Pinot Gris, Riesling and Pinot Noir as well as Sauvignon Blanc? “I can understand many people still think that if you are shaking the vine, you will lose crop,
that that is the only purpose of shaking,” Allen says. “But it is not. Shaking gets trash out, that if left will lead to botrytis outbreaks later in the season if conditions are favourable.” A New Zealand Winegrowers
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NZ WINEGROWER AUGUST/SEPTEMBER 2017 // 51