Agriculture Reference
In-Depth Information
Excess vigor reflects a lack of balance between the vegetative and reproductive
stages of a vine's development. When too much vegetative growth occurs, espe-
cially between flowering and veraison, fruit set can be poor and shading of the fruit
can lead to slow and uneven ripening, which affects the quality of the harvested
fruit. Even in dry regions, irrigated vines on deep, fertile soils can suffer from
excess vigor if too much water is supplied. Examples occur in the Murray-Darling
and Riverina regions in Australia and on alluvial soils of the Napa and Central
Valley regions of California. Chapters 3 and 4 discuss further the problem of
excess vigor induced by too much N and water, respectively.
Preparing the Site by Cultivation and Ripping
Soil treatment starts in summer. If the land has been cleared recently of trees
or old vines, all residues must be removed or burned and the soil cultivated
or ripped to bring up old roots that may harbor pest and disease organisms.
Deep cultivation to about 0.5 m in depth can be done with a moldboard
plow, which turns a furrow slice. Although effective in bringing up old roots,
moldboarding has the disadvantage of causing deep soil compaction, espe-
cially when the soil is wet, through pressure from the plowshare and tractor
wheels in the furrow. In calcareous silty-sandy soils in the Hérault region,
southern France, compaction of this kind has caused localized stunting and
withering of vines and yield decline (figure 2.11). Consequently, winegrowers
Figure 2.11
Stunted unhealthy vines as a result of compaction in silty, sandy soils in the Hérault
region, Languedoc-Rousillon, France.
