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Walnuts

Although most walnuts have their origins in North America and Asia, a handful of species are found in the Andes. One of these (Juglans neotropica) is so prized for its nuts, its fine and beautiful wood, and other products,1 that it is grown in nearly every highland town in western Venezuela, Colombia, Ecuador, and northern Peru.

The “Andean walnuts”2 that come from these trees are black shelled and larger than commercial walnuts elsewhere, although the size is somewhat misleading because their shells are unusually thick. The kernels have a fine flavor and are often used in pastries and confections. Women in the Ecuadorian town of Ibarra prepare a famous sweetmeat, the nogada de Ibarra, out of sugar, milk, and these walnuts.

Despite its value, this is a species in difficulty. Its hard, attractive wood is so highly prized for carving, cabinetmaking, and general woodwork, that demand for it has resulted in most of the sizable trees being felled. Throughout the Andean region, large specimens are now scarce, and commercial plantings are not being established. Because of the need for cooking fuel, many of these valuable trees are even being sacrificed for firewood.

Yet there are indications that this species could make an excellent plantation and village crop for the Andes and elsewhere. Seed nuts collected in Ecuador in 1977 have been planted in New Zealand and have grown rapidly. In the Auckland region, they have reached as much as 1.5 m growth per year during the first few years. That is comparable to the growth rate of Pinus radiata, New Zealand's fastest growing plantation timber. After 10 years, trees raised from these seeds were more than 10 m high and were bearing their third annual crop of nuts.3

The Andean walnut differs from better-known walnut species in at least two ways: the tree is almost evergreen (it grows virtually year-


1 These notably include dyes and a decoction of the leaves that is considered a valuable tonic.
2 Common names are tocte, nogal, nogal silvestre, cedro grande, and cedro negro. The name “tocte” is mostly applied just to the fruit; and the name “nogal” (walnut), just to the tree.
3 Information from D. Endt.


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OCR for page 323
Page 323 Walnuts Although most walnuts have their origins in North America and Asia, a handful of species are found in the Andes. One of these (Juglans neotropica) is so prized for its nuts, its fine and beautiful wood, and other products, 1 that it is grown in nearly every highland town in western Venezuela, Colombia, Ecuador, and northern Peru. The “Andean walnuts” 2 that come from these trees are black shelled and larger than commercial walnuts elsewhere, although the size is somewhat misleading because their shells are unusually thick. The kernels have a fine flavor and are often used in pastries and confections. Women in the Ecuadorian town of Ibarra prepare a famous sweetmeat, the nogada de Ibarra, out of sugar, milk, and these walnuts. Despite its value, this is a species in difficulty. Its hard, attractive wood is so highly prized for carving, cabinetmaking, and general woodwork, that demand for it has resulted in most of the sizable trees being felled. Throughout the Andean region, large specimens are now scarce, and commercial plantings are not being established. Because of the need for cooking fuel, many of these valuable trees are even being sacrificed for firewood. Yet there are indications that this species could make an excellent plantation and village crop for the Andes and elsewhere. Seed nuts collected in Ecuador in 1977 have been planted in New Zealand and have grown rapidly. In the Auckland region, they have reached as much as 1.5 m growth per year during the first few years. That is comparable to the growth rate of Pinus radiata, New Zealand's fastest growing plantation timber. After 10 years, trees raised from these seeds were more than 10 m high and were bearing their third annual crop of nuts. 3 The Andean walnut differs from better-known walnut species in at least two ways: the tree is almost evergreen (it grows virtually year- 1 These notably include dyes and a decoction of the leaves that is considered a valuable tonic. 2 Common names are tocte, nogal, nogal silvestre, cedro grande, and cedro negro. The name “tocte” is mostly applied just to the fruit; and the name “nogal” (walnut), just to the tree. 3 Information from D. Endt.

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Page 324 round) and it has no chilling requirement, probably because its native habitat straddles the equator where there are no true summers or winters. Although it is native to an equatorial region, the Andean walnut occurs at an average altitude of 2,500 m, where the climate is temperate. Temperatures vary between −3°C and 25°C (such extremes can occur even in the same day). The cold tolerance is unknown, but frosts occur regularly where the Andean walnut grows. It seems resistant to pests and diseases. The trees are often found growing along stream banks and the boundaries of fields, where they regenerate freely. PROSPECTS Andean Region. This is potentially an extremely valuable species for the whole Andean region. Germplasm collections should be made throughout. Types should be selected for large nuts, thin shells, fast growth, and other qualities. At the same time, other indigenous walnuts should be collected. These are probably less promising as nut crops, but they, too, are potentially valuable timber species. These include: Argentine walnut 4 (Juglans australis). Argentina and southern Bolivia. The nut is small and its shell is very thick, making the meat difficult to extract. However, the wood is prized for its fine qualities and is sought after for making guitars. Bolivian walnut 5 (J. boliviana). Mountains of northern Bolivia as well as southern and central Peru. Similar to J. neotropica, this species has grown well in Costa Rica. 6 Venezuelan walnut 7 (J. venezuelensis). Coastal mountains of northern Venezuela. The trees once occurred frequently in the mountains near Caracas but are now extremely rare, although they still exist between Junquito and the Colonia Tovar cloud forest. 8 No cross-pollination is required for nut production in the Andean walnut, but apparently hybrids can be made if they are desired. For example, hybrids between J. neotropica and the common (“English”) 4 Spanish names: nogal cayure, cayuri, nogal cimarrón, nogal criollo, nogal silvestre, nogal de monte. 5 Spanish names: nogal de la tierra, nogal negro, and nogal blanco. 6 Information from W.E. Manning. 7 Local names include nogal, nogal de Caracas, cedro negro, nogal plance, and laurel. 8 Information from J. Steyermark via W.E. Manning.

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Page 325 ~ enlarge ~ Turrialba, Costa Rica. Forty-year-old Andean walnut. This very large tree is about 27 m tall and 0.66 m in diameter. (M. Mora)

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Page 326 walnut have been reported. 9 The exploration of various hybrids might well lead to valuable new types. Other Developing Regions. Andean walnuts deserve to be included in forestry and agroforestry trials in areas of upland Central America and Brazil, the hill regions of India, Pakistan, and Nepal, and other seemingly suitable subtropical and tropical highland regions. Edible nuts are rare in many parts of the tropics, and their commercial production is practically nonexistent. However, the Andean walnut may provide a new, multipurpose tree crop for the middle-elevation areas of the tropics and for the subtropics. Industrialized Regions. Any walnut species that can reach 10 m tall in 10 years in a temperate area such as New Zealand deserves testing as a plantation crop. Worldwide demand for walnut timber outpaces current supplies, and outside the Andes this crop's potential is probably greater for timber than for nuts. Silvicultural trials should be initiated with this and other Juglans species in a search for the combination of fast growth and high-quality timber. Perhaps, also, robust hybrids can be created. For example, hybridizing the tropical species with some of the best timber and nut selections from the temperate walnut (J. nigra) might produce trees for the tropics that produce both high-grade furniture wood and fine-quality nuts. 9 Popenoe, 1924.