Agriculture Reference
In-Depth Information
of Switzerland, for example, where there is limited land for vineyards that is not
very steep (see figure 1.5, chapter 1).
Preplanting
In land previously under vines, there are likely to be pests and disease that should be
controlled before new vines are planted, as discussed earlier in “Soil Organisms.” For
example, in parts of California, nematodes and oak root fungus are problems where
old roots remain buried. The pathogenic fungus
Phytophthora
can also be present.
Since the phasing out of the ozone-depleting fumigant methyl bromide, products
such as Vapam HL (sodium N-methyldithiocarbamate) and Telone (1,3 dichloro-
propene) are being used to suppress or control nematodes and soil-borne diseases.
The websites
www.amvac-chemical.com
and
www.dowagro.com/soil/
give further
details for the use of these fumigants. Fumigation is most effective when the soil
surface is covered or packed down by rolling after the fumigant has been injected.
Because fumigants kill beneficial soil organisms as well as pests, a preferred option for
nematode control is to use nematode-resistant rootstocks (see “Biological Control
in Vineyards,” chapter 5), but this will not necessarily control soil-borne pathogens.
Legume-based cover crops plowed-in before planting stimulate beneficial soil
organisms, helping young vines resist pest and disease attack until they are well estab-
lished. Fertilizers can be applied when the cover crop is sown, but rock phosphate,
lime, or gypsum should be incorporated into the soil when it is ripped or plowed,
because their beneficial effects depend on coming into contact with as much soil as
possible. If the topsoil is shallow, soil may be mounded or “hilled” along the rows to
increase its depth and improve drainage, taking care that when rootstocks are used
the graft union is not covered. Mounding soil around the vine trunks in winter helps
to protect the vines in regions where severe freezing can occur.
Vineyard Layout and Vine Spacing
Vine spacing should be chosen according to site potential and grape variety to
satisfy the dual objective of high-quality fruit from each vine and optimum yield
per ha. Historically, in European vineyards, vines have been planted on relatively
poor soils on slopes, leaving the more fertile soils of river valleys and flood plains
for the cultivation of essential food crops. In maritime, and higher-rainfall con-
tinental regions (e.g., Bordeaux and Burgundy, respectively), vine rows could be
closely spaced (1 m) with close in-row spacings (1 m) so that fruit yields per ha
are optimized. Such close spacings accommodated the introduction of vertically
shoot positioned trellising, which improved leaf exposure to sunlight, provided
that the vine rows were hedged to prevent too much shading. Figure 2.16 shows
an example from the Médoc region of France where fit-for-purpose machinery is
employed for viticultural operations. In more arid regions, as in parts of central
