Andean Walnut

Family – JUGLANDACEAE

Botanical Name – Juglans neotropica Diels = J. honorei Dode

Other Names – Tocte (fruit), Nogal (tree), Ecuador Walnut, Tropical Walnut, Cedro, Black or Nogul Cedar

Introduction

In 1977 on a trip to Ecuador Dick Endt of Landsendt Nursery saw the potential for growing Andean Walnut in New Zealand. The first trees were planted in the Auckland area at Oratia,then later at Great Barrier Island. Other older plantings are in the Bay of Plenty where there is a mature tree cropping well.ⁱ
Ironically this tree was used as root stock for grafted English Walnuts, J. regia, instead of a tree in its own right.
Although it is reported as only growing in isolated stands overseas this may because the tree has been so exploited for other uses, as it is being grown successfully in a plantation in Taranaki.ⁱⁱ
It is a related to the American Black Walnut, J. nigra but much faster growing.
As with other nut trees it is wise to avoid planting near buildings.

Seedling trees in warm climates can hold leaves throughout the year which may account for its exceptional growth in New Zealand reportedly up to 1.5 to 2 metres per year in the early years in the Auckland area and 10 metres in 10 years in warmer parts of the country.
It is one of last trees to drop leaves – in July, if it does, and one of the first to regain them in early spring.
Leaves are shed to facilitate wind pollination in September and October. They can turn yellow in the autumn where temperatures are cooler.

Although relatively widespread in Colombia, the populations are considered vulnerable.ⁱⁱⁱ

Description

Deciduous fast growing tree to 27m height.

Leaves are large pinnate with 15-18 pairs of almost opposite leaflets, serrate, 5cm wide by 15 cm long with 15 vein pairs, (American Black Walnut J. nigra leaves are more alternate and smaller.)
They have a fragrant odour which lasts even when the leaves are dry.
New growth has a pinkish tinge.

Prominent leaf scars on trunk similar to J. nigra but slightly more pronounced.

Chambered pith.

Bark: More horizontal pattern than J. nigra when young.

Flowers: Monoecious. Male catkins, female terminal clusters.

Fruit: Drupe.
Thick indehiscent outer shell. Longitudinally furrowed thick shell covering convoluted kernel of dark colour.
Terminal clusters of 3-6.

Climate

As the natural distribution of the Andean walnut is in the highlands (up to 2000m) of Ecuador, Colombia, Peru and Venezuela, it is neither tropical nor temperate. Temperatures there are even throughout the year though they can vary between -3C minimum to 25C maximum on a daily basis.
The seasons are usually defined as wet and dry.
In New Zealand the conditions in northern areas are considered ideal. They are also growing in the Wairarapa where they have survived -4C and are doing well at Urenui (on the Taranaki coast where not subject to frosts); Bay of Plenty, Auckland and Northland where thousands of trees have been planted.
They are more frost sensitive when young and it is doubtful that they would tolerate severe frosts.

Andean walnuts have no chilling requirements, which is usually a prerequisite for growing other walnut species successfully.

The young trees are very prone to wind damage probably because the growth is sappy and brittle due to its long growing season – almost year round in New Zealand.
The top blows out easily in exposed conditions so shelter is vital. This is not such a problem as the tree matures.

Adequate rainfall is needed, as they do not grow well in dry sites.^iv

Soil

Most well drained soils are suitable but trees are susceptible to root rot if waterlogged especially in heavy wet soils.
They seem to do well near river beds where there is highly oxygenated water.

Flowers & Pollination

The trees are monoecious, bearing both male and female flowers on the same tree. No cross pollination is needed.
Hybrids can be developed if desired eg. Hybrids between J. neoptropica and J. regia have been reported (Popenoe, 1924).

Male catkins appear in September when any remaining leaves will be shed to assist in wind pollination.

Female flowers are in terminal clusters.

Propagation

The most economic way to propagate the tree is by sowing seed which is collected from trees of good shape and form.

Nuts are collected in June – July when they drop to the ground with the husk still attached.
Keep in containers until husks rot then a high-pressure hose can be used to separate the seed from the husk.
The clean seeds are then left to dry.

Sow seeds in September in propagating bed of open medium such as pumice sand about 15cm deep.
Place the seeds horizontally with the suture at the top to about the depth of the seed.
Keep moist until germinated usually October to November.
They will quickly form long taproots so pot on into PB12 bags.
Seedlings are fast growing so allow enough space.

They may be transplanted directly into the prepared site when about 10cm high or about December when danger of late frost passed.

Seed can also be sown directly into the site.

Planting

Best results are obtained with shelter trees or interplant with fast growing nurse crop species which need to be removed at the right time so as not to compete in later stages.
Weed control is needed especially in the first two years.

Spacing recommendation is at least 5 metres apart.

While some observations have been that Andean walnuts are not seen in large groups and it is thought that they prefer to grow in small stands, it may be that because of exploitation and other considerations such as changing climate, large groups are not able to be grown in its native country.

Plantation growing is being done successfully in NZ at Urenui since 1994.
The four-year-old plantings had reached a height of over 6m, form pruned yearly.

Pests & Diseases

They are not prone to pests and diseases but it should be stressed that they need good drainage to prevent root rot.

Cicada Amphisalta zelandica damage does occur in areas where it is prevalent such as the Bay of Plenty.

Nuts

In about 6 years or less from planting the trees will have a nut crop.
These are very thick, 5cm diameter, hard shelled, deeply grooved, larger than J. regia, with quality dark nut meat which is hard to extract.
It is used to make a sweetmeat with sugar and milk called nogada de Ibarra by the women of the Ecuadorian town of Ibarra and sold at the markets.

They are considered very nutritious [compare with recent trials as to efficacy of walnuts as cholesterol reducer with students at Lincoln University on their normal junk diet supplemented with walnuts (GP Savage, D McNeill 2000)]

Personally I have made Pickled Walnuts which are very tasty and go well with cold meats etc. It is very time consuming and labour intensive but worth the effort to use nuts that would otherwise be wasted.
It is a good idea to use rubber gloves in the initial stage as the nuts leave a nicotine-like stain on your hands which has to wear off as it does not wash off – after all it is used as a dyestuff. Recipe at end of this Fact sheet.

Timber

In early years Andean walnuts make rapid growth of 1.5 to 2m a year. It tapers off after the tree matures at about 10 years and the tree becomes more sturdy and wind tolerant.

Timber from these trees can be harvest in 30 years on good sites which is comparable to Pinus radiata.

Wood Description: Dark brown with blackish streaks; Grain straight to wavy, sometimes curled; Texture medium to fine, not always even. Diameter 0.9 – 1.50m

Mechanical Properties:
Medium bending strength and resistance to shock loads.
High crush strength and low stiffness.
Very good steam bending characteristics.
A compact, elastic wood with good strength properties.

Basic density 0.66gr/cm3, Elasticity 106.0 tn/cm3, Breaking 723.7 kg/cm3

Working Properties:
Worked easily with hand and power tools. Joints hold perfectly. Nails and screws easily.
Moderate blunting effect on cutters, but the finish is clean. Polishes to a very good finish.

Durability:
Moderately durable. Heartwood is resistant to preservative treatment and biodegradation. Sapwood is permeable.

Seasoning:
Dries well, but should be dried slowly to avoid twisting. Medium movement

Uses:
High-class furniture and cabinet making, musical instruments, turning, carving, sporting goods, decorative veneer, plywood facing, marquetry.

Comments:
Due to its shock resistance and elasticity, it is a good choice for rifle stocks.^v

Medicinal

The bark is boiled with other ingredients for use as a health tonic in Ecuador. Vernacular name cedro-cara.

At a Workshop on "Ecuador: Use and Trade of Medicinal Plants, Current Status and Important Aspects for Their Conservation" in Quito, September, 1999 it was reported that "90% of the plants used in traditional medicine are extracted from the wild, and not cultivated or managed.
Medicinal plants have not been inventoried and only 500 such plants are known.
This study identified 228 species as the most frequently used plants and 125 of these as the most widely marketed.

Of these 125 species, three are listed as timber species where commercialisation is prohibited: the Holy Wood Bursera graveolens, Balm Myroxylum balsamum and Andean Walnut Juglans neotropica.
Andean Walnut is also one of the six species listed as threatened.^vi

The leaves are strongly aromatic and when rubbed on the skin are an effective insect repellant.

In Ecuador the leaves have many uses including fabric dyes and a diet tonic.

As a species of the Juglans family it may be assumed that it could be used for similar medicinal uses as for J. nigra, J. cinerara, J.regia. (Checking this out?)

Related Species

Other indigenous walnuts^vii from the Andean region include:

• Argentine walnut Juglans australis; Argentina and southern Bolivia. (Spanish names: nogul cayure, cayuri, nogul cimarron, nogal criollo, nogul silvestre, nogal de monte). 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 J. boliviana; Mountains of northern Bolivia as well as southern and central Peru. (Spanish names: nogul de la tierra, nogal negro, nogal blanco). Similar to J. neotropica, this species has grown well in Costa Rica.

• Venezuelan walnut J. venezuelensis; Coast mountains of northern Venezuala. (Local names include nogal, nogal de Caracas, cedro negro, nogal plance, laurel). 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.^viii

Prospects

Carlos Mario Ospina Penagos wrote to me from Colombia with this report. (Some difficulty with my lack of Spanish) –

"In Ecuador three species (Bursera graveolens, Miroxylon balsamum and Juglans neotropica) have restricted use as their natural population has been almost destroyed; the species have been used for civil constructions, cabinetwork in general, cross ties of railroad and fuelwood among others, producing almost the extinction of the species.

At the beginning of the year I was in the cities of the Ecuador – Quito, Otavalo, Ibarra; and there I could observe the high degree of “deforestation” that the zone presents, caused by two things: Higher concentration of pollution near or around these cities; and a very dry zone (less than 900 mm of precipitation) – with a predominance of pasture grass, soils of sedimentary origin that combined with the strong winds have caused the zone high degrees of silica erosion, resulting in soils of the surrounding area that are almost sterile. The zone might be likened to a cold desert.

There is a second zone near a Tulcán, where the environment is more wet, soils derived of volcanic ash and some existing individual trees are dispersed. Unfortunately the Andean walnut is very threatened as it is used for the construction of houses, cabinet making, doors, windows, libraries, shade for the tomato of arbol Cyphomandra betacea or fuelwood. In this zone much pressure on the species exists which keeps it very restricted.

I might conclude that the species, due to its great use, to the high demand of the wood and little that this being done to revive the species, it is very threatened but not quite in extinction."

He then asks us for information regarding this species for a document they are compiling regarding geographic distribution, morphologic description, pregerminative treatments, germination, handling in nurseries, plagues and diseases, plantation growing, silvicultural management and uses.

As New Zealand’s seed source has come from this area I think it would be good to help out in whatever way we can. Do you know of any other places where these trees are growing?

Notes

From NewCrops HortPurdue: Observations in family gardens show Cyphmandra (Tamarillo) grow better in association with Juglans neotropica (Andean Walnut)

ICUN – The International Conservation Union reports that in Ecuador Juglans neotropica is one of three medicinal plants in which international trade is banned, and is one of the six on their list of threatened trees.

Recipe for Sweet Pickled Walnuts

In early December or when nuts are still green and able to be pricked with a darning needle or similar object, gather 100 green nuts (Black Walnuts seem to be later in the season)

Prick them all over pushing the needle right through. Put in large bowl with brine –

Brine:

6 oz (175gm) Rock or Plain Salt 2 qts (2.4 litres) Water

Soak for nine days, changing the brine every 3 days. Stir daily. Drain nuts and dry. Prick again and leave in sun until they go black (this may take a few days)

Pickling Mixture:

1 qt (1.2 litres) Malt Vinegar 1 teaspoon Allspice

1 oz (25 gm) Cloves 1 whole Nutmeg

3lb (1.325 kg) Brown Sugar

Boil mixture for 10 minutes and pour over nuts in jar. Seal and leave for at least 8
weeks

References

Dick Endt, Gerald Endt, Landsendt, Oratia, Auckland NZ

Lost Crops of the Incas, National Academy Press, 1989

Personal observations, G Newcomb

Compiled by: Gail Newcomb, Technical Editor, February, 2001.
Privacy removals and proprietory format conversion – December 2007

This crop guide was produced with the latest information available at the time of publication. This should not be considered the ultimate in information for New Zealand growing conditions: it is just a basic guide on the subject. If any member has information to add, or feels that any of the information is misleading, please use the contact below.

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