Wine Production : Vine to Bottle - Vinum Vine

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WINE PRODUCTION
soon as the grapes start to ripen. Some growers choose to
remedy this by netting their vines or using audible bird scarers.
• Snails: mainly a problem in early spring, especially where
conditions are wet. They will eat buds and foliage but also
encourage birds.
• Vine weevils: the adult weevils drill holes into the canes and lay
eggs. A legless grub then tunnels along the canes, seriously
reducing the strength of the vine.
5.2 Diseases
The vine can succumb to many diseases, the most important of
which are considered below.
• Botrytis cinerea: this fungal infection may be welcomed or
otherwise depending on circumstances. As grey rot it is most
undesirable and thrives in wet, humid conditions on vigorously
growing vines. It covers the leaves and the grapes with a grey
mould. Grey rot will result in off flavours in wine. However, its
effect on black grapes is greater than white because it causes
loss of colour, tannins and flavour. Outbreaks at harvest time
(often induced by rain) can wreck a vintage.
In its benevolent form, Botrytis cinerea occurs as ‘noble rot’
on some varieties of white grapes when certain climatic conditions
occur. The ideal conditions are damp, misty early
autumn mornings giving way to very warm, sunny afternoons.
Some of the great sweet white wines of the world are produced
from grapes affected by ‘noble rot’.
The grape varieties Sémillon, Riesling and Chenin Blanc are
particularly susceptible to noble rot. The fungus gets to work
by attacking the inside of the ripe grapes. It consumes sugar, but
more water, thus concentrating the sugars and effecting chemical
changes. The fungus then attacks the skins, which become
thin and fragile and take on a brown/plum colour. The grapes
are then known as ‘fully rotted’. In a further stage, the grapes
will dry up and appear wrinkled. This is the state of perfection,
and is known as confit. The individual berries within a bunch
may well be at different stages of attack. Thus the pickers
(usually local people who are experienced at selecting the