Wine Production : Vine to Bottle - Vinum Vine

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in South Africa. It was first recognised around 20 years ago.
Like Phylloxera (for which it can be confused), Margarodes feeds
on vine roots, and results in stunted growth, leaf discolouration,
leaf death, and low or no crop. Over time, vine death is inevitable.
However, if the vines are encouraged to root to a depth of 3–4
metres, a depth at which the pest cannot survive, prolonged, if
stunted, survival of the vine is possible. Heavy rainfall or flood
irrigation can reduce pest numbers. Some producers are now
grafting to try and combat the pest, but American rootstocks
may not be resistant as they are with Phylloxera. Margarodes
can have the positive effect of restraining vine vigour.
• Grape moths e.g. pyrale (Sparganothis pilleriana), cochylis
(Eupoecilia ambiguella), and eudemis (Lobesia botrana): the
caterpillars of these flying insects attack the buds of the vine in
the spring and later damage the grapes, allowing disease to
set in.
• Nematodes: microscopic worms that feed on the root system,
causing a variety of problems for the vine, including water stress
and nutritional deficiency. Some species can spread virus
diseases through the vineyard. In areas where nematodes are a
problem, growers should choose nematode-resistant rootstocks.
• Spider mites: these belong to the Tetranychidae family and are
mites rather than true spiders, having no separate thorax and
abdomen. Species include the red mite and common yellow
mite. They infest the leaves and restrict growth.
• Grape erineum mites (grapeleaf blister mite): these live on the
underside of leaves, causing galls that affect the growth of
young vines.
• Rust mites: these belong to the same species as grape erineum
mite, but are generally found on the upper surface of the leaves.
They cause a reduction in yield. It is interesting to note that
mites were largely unknown in vineyards before the 1950s,
when the introduction of certain insecticides destroyed the
previous biological balance.
• Animals: these include rabbits, hares, deer, wild boars, and
kangaroos which dig, burrow or gnaw, and can be very destructive.
Rabbits and hares can strip bark and leaves, whilst larger
animals are partial to the grapes.
• Birds: can be a serious problem during the grapes’ ripening,
stripping vines of fruit, especially where vineyards are fairly
isolated. Birds are selective and begin their destruction as
CHAPTER 5