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Lice- Sadly Not Just for Mammals…

1/21/2013

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You may’ve heard somewhere about an epidemic that pretty much eviscerated France’s vineyards when it was introduced in 1868. If not, you’re about to. 

First, a little background on the difference between European and American grapes: 
Both European and (most) American grapevines share the same genus: Vitis. However, European grapes are of the species vinifera, whereas American grapes are of different species such as V. labrusca, V. rupestris, V. riparia and many more. 
(Sorry for all the technical botany stuff- it’ll come in handy later, I promise. There will be no exam!)

Phylloxera, a tiny root louse, was introduced when American grapes were taken back to France for experimental planting. It is native to many eastern regions of the US so many American vines have developed enough resistance to keep living and producing fruit (though not truly an immunity as some will suggest.) However, V. vinifera, having evolved in Europe, had no such defenses. So when phylloxera was introduced to France in soil surrounding American vines, the destruction was brutal. By 1900, close to 75% of French vineyards had been severely affected and it had also spread to the rest of Europe, causing a major economic disaster

So, what to do?

Because European wines had come to depend on specific varieties (Cabernet Sauvignon, Chardonnay, Pinot Noir, etc) it wouldn’t really do to just start making wine out of American grapes. They have some significant taste differences (think of the specific flavor of Concords) and much tradition would be lost… 

Due to the way grapevines reproduce (I actually won’t go into detail here,) cross breeding between American and European grapes wouldn’t be ideal either- you’d lose the traditional varietal color and flavor characteristics and there’s no way to guarantee that the phylloxera resistance would actually be passed on.

So, that’s where grafting came into play (this totally blew my mind when I first learned of it- and seeing it done in person was awesome.) It is now commonplace to take the roots and below soil portion of an American grapevine and graft it to the upper, fruiting portion of a European variety. Voila! You have a plant that produces yummy, traditional wine grapes on the top, yet has roots that won’t get destroyed by lice! The vast majority of grapevines in Europe (and many in the US) are now rooted on American rootstock! Pretty neat, huh?


Did you know? 
Due to the phylloxera epidemic, most states with significant viticulture observe strict quarantine rules and participate in clean breeding programs led by UC Davis. Though many vineyards are not legally required to participate, they are strongly encouraged by state agencies. Washington State has yet to see any significant phylloxera infestation thanks to these efforts. Similarly, Australia has seen little to no infestation and is the only place in the world where Vitis vinifera is commonly grown on its own roots.
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Berry to Bottle... in a nutshell.

1/16/2013

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For this first post, let’s talk a little bit about how wine is made. This is possibly review for some of you, but who knows? It could be mind blowing new info! 
This will likely be wordier than most of my entries, but it’s laying out some (bare bones) fundamentals, so bear with me.

At its most basic level, wine exists because of fermentation: yeast + grape juice = alcohol, carbon dioxide, and a little bit of heat.

Wine stops fermenting on its own eventually because alcohol is toxic to yeast (kinda sad that the little guys produce the very material that winds up killing them…) The yeast gobble up most of the sugars and nutrients in the grape juice, until they've made enough alcohol to kill them off.  
(As a rule, white wines are less alcoholic than reds and alcohol by volume in finished wines tend to range between 11%-this is really low- and 15%-this is really high and usually only happens in fortified wines- more on those later.)   

Alcohol content can be controlled by the winemaker by stopping fermentation before the yeast eat up all of the sugar and nutrients, leaving a lower ABV (alcohol by volume) but the wine will contain residual sugar.  If a wine is allowed to ferment till it finishes on its own (called fermenting to dryness because it means it has used up all the sugar, and dry = not sweet) and still has a really high alcohol content, this is likely because the grapes were really sugary to begin with and probably involved the use of a yeast strain that is more resistant to alcohol. 

Most winemakers harvest their grapes once they know they contain a sugar level that will give them the eventual alcohol concentration (and residual sugar content) that they want for the type of wine they’re making.

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    I'm a wine-loving actress in the Windy City who holds certificates in Enology and Viticulture from Washington State University. I also own a hilarious cat.

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