5th International Walnut Conference
Sant'Agnello di Sorrento, Naples, Italy
by Jon McCosh¹ and Gabriel Hemery²
The generosity of Woodland Heritage, in providing two Garthwaite Bursaries, allowed the authors to travel to Italy to attend the 5th International Walnut Conference. Dr. Hemery presented a paper entitled "Advances in Walnut Breeding and Culture in the United Kingdom", whilst Jon McCosh attended to learn more about the growth and production of walnut timber.
The majority of the commercial production of walnut, both for veneer timber and nut processing, comes from three main species and their hybrids:
The ‘English’ Walnut Juglans regia is native to the Middle East, with a natural range from Bhutan in the East to Turkey in the West, and from India in the South to Kyrgyzstan in the North;
The ‘Black’ Walnut Juglans nigra is native to North America, with a natural range encompassing the majority of the eastern United States;
The ‘Arizona’ Walnut Juglans major is native to North America, with a natural range from west Texas, to central Arizona, to northern Mexico.
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The gathering of Nutters |
These species have been collected and cultivated for hundreds of years, this has lead to a profusion of cultivars, each with its own particular qualities. Walnut is now grown worldwide, from Chile and Argentina in South America to the north of the United States, in Australia, China, the Middle East and the majority of temperate and Mediterranean Europe.
Delegates from 18 countries converged on Sant’Agnello di Sorrento for the Conference which took place from 9th to 13th of November 2004. Over the four days of the conference, a total of 161 papers and 99 posters were presented to the delegates, these encompassed: Economical Aspects of Walnut Production; Genetics and Breeding; Biotechnology; Biology and Physiology; Propagation and Rootstocks; Walnut Cultivation in China; Pests, Diseases and Plant Protection; Orchard and Forestry Management; Nut and Wood Processing; and a Technical Tour of a Veneer Mill, and a Nut Processor.
Talks of particular interest were given by a number of delegates, they included:
H. Schepers (Netherlands), who has made promising trials of Walnut cultivars in an agroforestry project, this will be an interesting area of ongoing research;
E. Voulgardis (Greece), who noted that currently the greatest demand for Walnut veneer is in Italy, and that the demand was for lighter coloured timber;
T. Ameglio (France), who showed why walnut is frost tolerant under many conditions;
D. Jacobs (USA), who demonstrated that the genetic quality of the tree is more important than the sowing density in tree nurseries;
The Chinese Group, who spoke eloquently about Walnut cultivation in China, and their hopes for the future;
B. Mariotti (Italy), who talked about the development and architectural traits of walnut, grown for timber, in pure and mixed species plantations; and lastly;
S. Dernini (Italy), who highlighted the nutritional qualities of the walnut, especially the fact that walnuts are a ‘vegan edible’ provider of essential oils and amino acids.
Most the presentations will be made available in a special issue of Acta Horticulturae, later in 2005. This will be available from the International Society for Horticultural Science’s dedicated website for the journal: http://www.actahort.org/. Gabriel Hemery’s paper, written jointly with Karen Russell from East Malling Research, provided an overview of all walnut work in the UK. The abstract is reproduced below:
Walnut (Juglans spp.) has not been widely cultivated for timber or fruit production in the United Kingdom (UK). Recent research activities in the UK have stimulated renewed interest in common walnut (J. regia), black walnut (J. nigra) and hybrids as providers of valuable timber on relatively short rotations, and in the case of J. regia, as a highly marketable fruit crop. In addition, these walnut species are also likely to be more suitable than many native tree species to the climatic conditions predicted for the UK within a single generation. A substantial collection of walnut germplasm has been established through complimentary research programmes at the Northmoor Trust (NMT) and East Malling Research (EMR). The NMT programme has concentrated on J. regia for timber production. Genotypes were collected across 11 countries from both the introduced and natural ranges of the species, amassing a total of 371 half-sib progeny, primarily from the walnut-fruit forests of Kyrgyzstan. Five-year results for survival, growth and phenology from the trials are presented, indicating significant variability for growth and phenology. A series of silvicultural trials have been established aimed at improving establishment and early growth of walnut species in the UK. The programme at EMR has focussed on establishing a clonal collection of 78 timber selections (J. regia, J. nigra, J. major, and their hybrids) and 66 J. regia fruit varieties from breeding programmes across Europe and the United States of America (US). Jointly, NMT and EMR have initiated a black walnut timber improvement programme, comprising seedling progeny from 7 European countries and 13 States in the US. The genetic resource within these combined programmes provides an unrivalled resource for breeding and genetic improvement both for timber and fruit production, and for genetic diversity and adaptive trait studies.
At the end of the conference there was a technical tour to a veneer mill. This was a most instructive and well presented visit. The veneer mill used old but effective machinery, employing 16 workers, and was obviously very well run. The manager of the mill made some interesting observations: firstly, that the European market required both light and dark timber in its walnut veneer; and secondly, that dark veneer was not in great demand for the Italian furniture industry.
The conference raised several issues of particular relevance to Britain. Global warming will have a very important part to play in the future of our forestry industry. Walnut is already well adapted to severe cold, but requires hardiness to late spring frosts to be truly successful in the UK environment. The development of late flushing cultivars and hybrids with good vigour will help in this process. Walnut does not often produce a straight tree without pruning. Thus, time and effort must be expended to ensure that the tree grows with the correct form for timber production (extra costs for the timber grower). This is where the Northmoor Trust is aiming to make a difference through the genetic improvement of the species. The research programme aims to improve walnut and will eventually result in late flushing, high vigour, straight growing walnut trees ideal for the British market. In 2003, the rewards for producing a first class veneer log were £600 per cubic metre. High quality walnut for gun stocks and furniture making are also very profitable.
The conference highlighted the significant progress we have recently made in promoting walnut in Britain often, it must be said, with the support of Woodland Heritage. However, our breeding programme is a generation behind those in France and elsewhere. The lack of vision from policy makers in Britain prevents further interest in the species from the forestry industry, whilst funding for broadleaved research remains minuscule. Without the support of Woodland Heritage and the other main partners in the British and Irish Hardwoods Improvement Programme, there would be no such work at all. International conferences such as this provide a real insight and sense of perspective, which is crucial if we wish to realise Britain’s forest potential.