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Winemaker’s Bookshelf

We have the tools to affect wine quality, even in the face of growing seasons that change dramatically fromyear to year.


’mnot sure if we setmany records, but 2013 has been a hot summer in Summerland. It’s quite

a contrast to a few of the cooler Julys we’ve had over the past 10 years; close to twice the accumulated degree days. I’mnot about to debate why it’s been hot this year, but I would like to talk a bit about what we can do about it.

One of the technical papers that I’ve

often referred to students is a review by Jackson and Lombard (1993): Environmental andManagement Practices Affecting Grape Composition andWine Quality 44:4 pp 409-430, AmJ.Enol. Vitic. Yes, I realize the review is 20 years old, but it’s a concise summary of the factors that affect grape composition and the relationship between berry composition and wine quality. The take-awaymessage fromthis

paper is that through appropriate management of crop load, shoot placement, vigour, irrigation, and grape variety we have the tools to affect wine quality, even in the face of growing seasons that change dramatically fromyear to year. An important book that I have

already reviewed in this column is Viticulture and Environment (1992) by John Gladstones. This was a herculean work in which Gladstones surveyed the geological, cultural, and climatic factors affecting everymajor viticultural region of the world and related those factors to wine styles and quality. Inmany ways, the book is similar to

the Jackson and Lombard review, but muchmore detailed. The bottomline of these two publications is that by using appropriate responses to environmental changes we can optimize wine quality when growing conditions change. Fundamental to all wine quality is

British Columbia FRUIT GROWER • Fall 2011 29

By Gary Strachan Whither the weather?

the terroir in which the grapes are grown. Terroir seems to be creeping intomore common English useage, probably because there is no English word broad enough to encompass itsmeaning. It is used

to express the sumof all factors of a growing location that affect the cultivation of grapes. Whether the considered area is broad or specific, the word can still apply. Gladstones’ second book,Wine, Terroir and Climate Change, expands onmany of the discussions developed in his first book andmoves forward into new ground, especially in the exploration of the factors affecting terroir. It’s difficult to estimate whether

grapes will provide optimal yield and quality in a site or region with no history of viticulture. Even within a site with a demonstrated history of

grape cultivation, the choice of the best grape cultivar(s) bears the risk that matching average frost free season to a

cultivar’s interval between bud break and harvest

may be too short or too long. It’s especially difficult to transfer data fromanother area and apply it to local conditions. Gladstones discusses the problem

that assessing a site based on average growing degree days usually doesn’t work, especially at extreme latitudes. This question has been raised by

other authors during the past 20 or 30 years. Gladstones not only reviews their proposals but draws conclusions

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