An extract from Module 1 b of

Diploma in Viticulture

1.6 European and American Varieties

An Introduction

In the first part of this module we looked briefly at the history of the grapevine and the peoples, countries and cultures that contributed to the establishment of what is now a major world industry. In this second part, before moving on to look in detail at morphology and physiology, we will consider the varieties and distribution of grapevines that have been developed, the role of climate and the demands for different products in different regions.

Viticulture and horticulture are, obviously, important branches of mainstream agriculture but there is a fundamental difference in the way that these branches have developed when compared with agricultural field crops. In the latter, innovation and progress, particularly with regard to  crop yield and quality, has been primarily confined to the genotype whereas in the former, particularly viticulture, it has been primarily seen at the level of husbandry. Wheat production, for example, has seen the introduction of a large number of new cultivars which have been developed and introduced in response to economic and biological demands ~ new technology and epidemics. The lead time for the release of an improved or disease-resistant cultivar is now about ten years. In complete contrast, the cultivars of fruit crops change very slowly or not at all. Most of the world's vineyards are still planted with traditional grapevines, maintained for many centuries via vegetative propagation. For example, the 'Shiraz' vine (syn. 'Syrah', 'Hermitage') is thought to have originated in Syracuse and to have been introduced to the Rhône valley by the Romans. The history of most other cultivars is equally long and fascinating.

In viticulture the main responses to biological constraints or economic change has been to manipulate the existing, traditional cultivars by applying progressively higher standards of husbandry. Included here are innovations in basic, standard husbandry (rootstocks, pruning, training), in chemical-based husbandry (fertilisers, pesticides, growth regulators, herbicides), in mechanisation (mechanical harvesting and pruning) and, of course, in post harvest technology and processing.

Whilst there has been some significant progress in the development of new rootstocks during the last hundred years or so, plant breeding technology has had little impact on viticulture at the level of the scion. The reasons for the persistence of traditional European cultivars are many and involve a complex mix of both plant and human factors.

Wine production accounts for some 80% of the world's grape crop and, although we emphasize the wine grape here, it should be remembered that table grapes and those produced for drying (raisins) are subject to very similar circumstances.

The breeding of woody, perennial fruit plants is fraught with considerable technical difficulties.  Grapevines are highly heterozygous outcrossers and do not breed true to type from seed. Furthermore, the characteristics found in a good cultivar are polygenic in their inheritance and are controlled by large numbers of genes of minor effect; very few important traits are controlled by single genes with dominant alleles. The traditional cultivars are comprised of highly subtle gene combinations which are only able to be maintained and conserved by way of vegetative propagation. The wines produced by these cultivars have unique characteristics of style and quality that enjoy a very high level of consumer acceptance.

The products of these cultivars have become firmly entrenched in the world market place and technology has developed in order to enhance the growing of the traditional cultivars and, particularly in Europe, this has been firmly established by both custom and law.

There are, however, strong pressures for change evident in all fruit-growing industries, not least viticulture, being applied by both economic and social forces. The cost of production in modern, intensive viticulture is high and includes a significant energy component. Chemical crop protection is not only very expensive but an increasing source of consumer unease in terms of both public health and damage to the environment. This disquiet has resulted in increasingly stringent environmental protection legislation and a significant slowing down in the development of new plant protection products. Rural industries in most countries of the world are becoming increasingly vulnerable to new pests and diseases and restricted, by either economics or legislation, in the ways they are able to deal with existing ones.

All of these factors lead us to the conclusion that we must replace chemical controls with genetic resistance, husbandry must be simplified and a high priority given to innovations in plant breeding. Whilst continuing advances in the latter provide at least some grounds for optimism, given the technical difficulties and other disincentives outlined above, it is reasonable to question whether these goals are attainable.