Wine Production : Vine to Bottle - Vinum Vine

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desired berries) have to return to the vineyards several times
in a series of successive pickings in order to select the confit
grapes. This process is, of course, extremely costly. The
grapes must be picked when dry, and the harvest sometimes
continues until late November in the northern hemisphere. The
quality and quantity of vintages varies considerably – the crop
is at the mercy of the weather, and in some years Botrytis
cinerea does not develop successfully.
• Powdery mildew, also known as oidium (Uncinula necator):
this fungal disease reached the vineyards of Europe from
North America between 1845 and 1852. It causes pale grey
spores to grow on leaves of the vine and it can overwinter
inside the buds. Eventually the grapes will split and shrivel.
The disease thrives in mild, cloudy conditions and especially
where there is a dense, shady canopy of leaves. It may be
treated by dusting the vines with sulphur powder.
• Downy mildew, also known as peronospera (Plasmopara
viticola): this is another fungal disease that came from North
America around 1878, probably on vines being imported as
grafting stock to combat Phylloxera. The disease thrives in warm,
wet weather, common to many North European wine regions.
At least 10 mm of rain in a 24 hour period is necessary for
there to be an outbreak. Dense white growth forms on the
underside of young leaves. When attacking the grapes, it
causes the berries to shrivel up and turn leathery. It may be
treated by contact or systemic methods: a common contact
treatment is spraying the vines with ‘Bordeaux mixture’ –
copper sulphate and lime. Vineyards thus treated often show
a blue hue, and the sprays even give a blue tint to pebbles or
gravel on the soil surface.
• Phomopsis (Phomopsis viticola): a particular problem in New
Zealand, but found in other cool regions, this disease spreads
in wet springs and manifests as black spots surrounded by
yellow rings on leaves. Black cracks appear at the base of
shoots, which can then break off.
• Black spot, also known as anthracnose (Elsinoe ampelina):
this is another fungal disease that needs wet weather and can
attack young foliage.
• Eutypa dieback (Eutypa lata): this fungal disease usually attacks
older vines, entering through pruning wounds, and results in
vine arms dying.
CHAPTER 5