Vintage Lefton
Vintage Lefton
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US $9.99
Botrytis bunch rot or grey mould is a disease that exists in all vineyards worldwide and is caused by the fungus Botrytis cinerea. Botrytis can hit grapes at any time but the most common infection time is when they are very nearly ripe. Botrytis bunch rot stays alive during winter on the bark, in dormant buds and in debris under the vine. That's just one reason to keep the vineyard clean. Botrytis spores are produced in spring and infect leaves and berries. Water is required for germination and long periods of wetness with high levels of humidity are ideal spore production conditions.
An infection period during spring will kill off the flowers and/or the berries on the vine. This means a vastly reduced yield. Instead of the full number of ripe berries on the bunch we may be getting only 50%. Any break in the skin of the berry from birds, wind, splitting due to hail or sunburn provides an easy infection entry point. Eventually the entire bunch becomes a grey mouldy mass of spores. In dry weather the berries dry up and there's very little damage further on. During wet wether the berries burst and spread the mould further.
We manage botrytis in the vineyard in two ways: environmentally and chemically.
Environmental management includes changes done to maximise the airflow around the vine canopy to decrease humidity. Different trellising, pruning and leaf plucking methods are used to manage the canopy density. Everything possible is done to minimise berry splitting. We go to great lengths to keep the weeds down under the vines and the ground as clean as possible as botrytis can survive on vine prunings and even weeds.
Chemical management involves sprays to kill the fungus before it multiplies rapidly or 'blooms'. Wet humid weather is the danger time when we have to monitor the vineyard daily and spray regularly. Flowering and 'bunch closure' (when the bunch rapidly fills in, late spring to early summer) are the two crucial periods.
Legend has it that in 1650 a priest had his harvest delayed when the Turks attacked. When they returned to the harvest they found a fungus had grown on some bunches. They wondered what the wine made from these grapes would taste like and were pleasantly surprised. The Germans and then the French were next to follow with the botrytis or 'noble rot' wines. The best grapes for noble rot wines are Riesling, Gewürztraminer, Semillon, Sauvignon Blanc and Chenin Blanc.
The botrytis fungus will puncture the skin and slowly draw out the moisture from the grape. This produces grapes with much less liquid than normally ripe grapes and consequently a much higher sugar concentration. Grapes are carefully harvested. The harvest may occur in stages. One pass will pick up the ripest grapes. You then wait for a few days and harvest again to pick up only the very ripest grapes in the block. If you leave it too late you can smell the vinegar walking through the vineyard. Then you know you've left it too late. You have to pick the grapes while they're still moist raisins, not when they've dried up.
Needless to say this is a very slow and precise process. You definitely can't machine harvest a botrytis crop. The very rot that you are fighting off for most of the year is what you desperately hope for in the final weeks and days of harvest.
The term 'late pick' is used synonymously with botrytis wines but is not the same thing. Late pick means just that. The fruit is left on the vine to very slowly ripen and wither on the vine. The same concentration of sugars that happens with 'noble rot' happens naturally in late pick grapes. The botrytis infection just helps speed up this natural process. The harvest is delayed while the grapes literally wither on the vine producing almost raisins with incredible sugars and favours.
If all the sugar in these grapes were fermented we would get a wine of around 20% alcohol content. However, the yeasts used to start the winemaking process will die when the alcohol content reaches around 15%. This leaves a beautifully balanced wine with good crisp acids, plenty of sugar for sweetness and lots of alcohol. An environment of approximately 15% alcohol content by volume becomes toxic to the yeasts. Normally the yeasts would happily continue multiplying and consuming sugars until they ran out of food. In the case of botrytis wines the yeasts do their job so well that they produce a toxic environment for themselves.
In the winery the grapes are hard to work with. The juice flows like molasses, not like normal grape juice. The pumps are working harder and everything is sticky. The botrytis grapes are always the last ones to be picked so they're coming through when the winery has been cleaned up after harvest. Almost an afterthought.
But when you open a sweet bottle of 'noble rot' wine, all the troubles are truly worth it.
And, an interesting point. In Australia it is illegal to add sugar to wines. We can add acids (tartaric, citric etc) but not sugars. In the rest of the world it's the other way around. You are allowed to add sugars (chaptalisation is the winemakers term for sweetening wines by adding sugar) but you're not allowed to add acids.
Keep any eye out for these wines as they are wonderful addition to any meal or any evening. If you haven't tried any, make sure you do as you are missing out on some wonderful drinking.
The Gurdies Winery is one of Australias premium cool climate wineries. The weekly newsletter gives you a snapshot of 'This day in wine history', more articles like this plus vineyard and winery news. Sign up at the website http://www.thegurdieswinery.com.au or send a blank email to whatson@thegurdieswinery.getresponse.com
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Psychology By Lefton, Lester A./ Brannon, Linda $115.18 Author: Lefton, Lester A./ Brannon, Linda Publication Date: 2007/12/01 Number of Pages: 850 Binding Type: Paperback Language: English Depth: 1.00 Width: 8.00 Height: 9.25 |
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Vintage $11.99 Vintage |
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Outlines and Highlights for Psychology by Lefton, Isbn : 0205418139 $32.13 No Synopsis Available |
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Outlines and Highlights for VanGo Books Psychology by Lester a Lefton, Isbn : 9780205595310 $34.08 No Synopsis Available |
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