You’ve heard of that ‘old chestnut’ – perhaps we have defined it here:

The Chestnut industry in New Zealand has been arduously nutted out many times over; but it always seems to relegate itself into the ‘nearly made it’ chest.

This time – 2013 – there still remain international markets pleading for product.

A leading tree propagator of great experience holds a bud grafting workshop featuring chestnuts.
He has supplied thousands of trees over decades for this elusive industry –
Where is this chestnut industry that has swallowed up so much effort?

While we wait for answers from the many people attempting a rebirth, let us see what we can find from the archival chest of dreams about this unfulfilled crop.

Below is a Basic Crop Fact Sheet from 1997, abridged only to remove references to authorities believed to be no longer with us.

We intended to follow up with coverage of recent progress outlined at the field day (embargoed), much of which is inspiring.  (We never did find a reliable method for returning to topic after the 3-month hold, but thankfully those requirements have eased.)

Meanwhile, a great export market goes unsatisfied – which we are well placed to supply.

See the Chestnut Cart in the Nut Crops Summary

← Back to Nuts

Written by Eric Cairnes, NZTCA – February 2000

So you’ve bought or are thinking of buying a rural block and perhaps earning some retirement income from growing something, preferably something you yourself like eating.  What about nuts? They are high value, store well, are eary to transport, lend themselves to niche marketing and can be managed on a fairly small scale.

Remember the in shell nuts you indulged in over Christmas.  If you chose well, you found some excellent quality locally grown walnuts or hazels.  Most of us however, bought mixed packs of nuts imported from around the world.  They were stale and rancid and we wondered why we had bought them.  Well perhaps its too cold for Brazil nuts here and peanuts are pretty marginal, but, almond, walnut, hazel, macadamia, pinenuts and chestnuts do well.  And how much better they would have tasted fresh.

The New Zealand Trees Crops Association, which has branches in most areas of the country, can help you get started, and most importantly, can put you in contact with other growers around NZ.  Information is willingly shared at field days and evening meetings and through fact sheets, because we recognise that this is the best way to learn more ourselves.

From time to time there are specialist nut seminars held, and the annual conferences (this year at Lincoln over Easter Weekend) nearly always feature field events and seminars given by experts on nuts.

So if you are serious about a commercial nut venture, you should do your homework.  Check out the world scene for indication as to potential.  (Get yearbook data and search the Internet).  Monitor trends in world prices, trends in planting and disease.  Does NZ offer a strategic advantage (eg. season, climate, disease, access to markets etc)?  What is the size of the local (ethnic) market?  What are the costs of growing and harvesting/processing the crop?  What supporting infrastructure is there to assist you?  Membership of NZTCA makes it easier to find answers for these and many other questions.

Decide how to market you crop.  Will you drop it on the local auction system, and accept commodity prices, or develop niche outlets for processed products and control the situation better.

In a general sense, the marketing aspect is the biggest hurdle for most small scale industries.  In NZTCA, many of us are green fingered growers, and not strong on the presentation/marketing end.  However, there are also many market success stories for niche products.

A new product in NZ such as gevuina nuts, may have difficulty establishing market demand unless there is sufficient supply.  Wholesalers or large retailers may not want to invest in promoting or stocking a product line unless quality and supply is secure.  Thus, even for products where there is established demand, but no local supply (eg pine nuts and pistachio), there is a ‘critical mass of product’ required to develop the market.  This amount is quite likely more than one or several growers could supply, so don’t try to capture the market on your own.  If you are keen on exporting, the amount of product to do business with may be orders of magnitude greater than would be necessary for domestic markets.  Our advice is to cooperate with other growers to develop the infrastructure and markets.

Thus one of the strategies of the newly formed Gevuina Action Group is to get as many trees as possible planted as soon as possible in order to be able to “launch the product”.  Quite deliberately, they are focussing on a few selections into order to standardise the product.  Naturally there are risks involved with new crops if the best selections are not yet known and market demand is uncertain.

In the case of macadamias, walnuts, chestnuts, and hazels, there is now an established demand for local produce (or for export) and some established infrastructure to harvest, process and market the produce.  The NZ Hazel industry is still very small, and gevuina, pistachio, almond, pecan, and pine nut are yet to gain ‘critical mass’ but gate sales and specialist retailers would still be interested in spot market sales.

The history of serious nut growing in NZ is quite recent and began with the foundation of the New Zealand Tree Crops association, 25 years ago.  Some of our early researchers were also on the staff at DSIR or MAF and no doubt this assisted with the professional approach and early successes.  A key trial area for nuts was the Crop research block at Lincoln and the cooperative venture with the then DSIR was a major success story.  Some of these trials continue in the grounds of Lincoln University under the auspices of Dr David McNeil, a Research and Development Coordinator for NZTCA.

Before the formation of NZTCA, no one had done any systematic selection or breeding of nut trees suitable for NZ conditions.  We weren’t even of the limitations of our climate.  How then to develop a nut industry?  The quickest way was not to spend 15 years breeding new varieties but to see how existing material would perform. The opinion was that NZ conditions were sufficiently different to other major nut producing countries, that imported varieties may not be any better than some selections already growing and adapted to NZ.

So in order to get the industries started, NZTCA held nut competitions to identify the best walnuts, chestnuts and hazels.  The best of these were then propagated and put into trial plantings and compared with the best overseas varieties.

In the case of walnuts, some local selections have done extremely well and four of these (Rex, Meyric, Dublin’s Glory and Stan) were given variety names in 1998.

Some of our local hazel selections (eg Whiteheart) also compare well against Italian and American varieties.

In the case of chestnut, due to the prevalence of chestnut blight in most other countries, there was reluctance to import any new overseas material.  Some did eventually get imported, but our local selections still form the bulk of the plantings.

With the founding of NZTCA, it still took 15 – 20 years of development to get walnuts, chestnuts and hazels to an industry size.
The nut crop summary below – Walnut – Chestnut – see also Nut Crop Guides may help you decide whether your favourite nut can be grown on your patch.

Walnut Chart

Species: Juglans regia commonly known as European, English or Persian walnut.

Recommended Varieties	Numerous seedling and grafted selections available. It is important to match the orchard site with the right variety. Research is still continuing to select the best varieties for North Is conditions.
Climate	Rain or high humidity during spring to late summer increases the incidence of blight. Some varieties are more susceptible to blight than others. Dry east coast climates are preferred. The leaves and flowers are damaged by unseasonal frosts. Areas subject to frost after mid October may benefit from late leafing varieties.
Soil	Critical. Must be free draining down to 2 metres. Fertile soils of moderately high pH are required. Nutrients need to be well balanced.
Markets	Present local consumption far exceeds local supply and quality NZ kernel is readily sold. Said to one of the few commodity products which has maintained its value over the years. The (heart) timber is amongst the most valuable wood there is, provided it is well grown and trees of large size. Walnut burr is particularly sort after. Heart content varies greatly.
Harvesting	The nuts fall to the ground and must be harvested within a day to avoid deterioration. Various machines (vacuum and hedgehogs) available to pick up nuts. In dry climates, daily collection is less critical.
Post-Harvest	Nuts should be cleaned by water blasting and dried promptly. They will go mouldy if kept damp too long or bagged before internal moisture content is low enough. For home use, air drying on racks is adequate. Assisted drying is required commercially.
Orchard layout	Grafted trees are recommended for smaller orchards or where uniform nut quality is critical. Certain seedling lines come remarkably true to the parent. In humid climates, timber may be the preferred objective. Where timber production is required, initial spacings should be 4 x 5 metres. Half of these should be thinned out in stages. Where nuts only are required, use grafted trees at a maximum of 10 x 10 metres. Having more than one variety will assist with pollination.
Orchard Management	Fertiliser is required. Mowing or spraying under the trees enables easy nut collection. Roots stocks can be J. regia or the hybrid “paradox” for well drained soils. J. nigra is preferred for wetter soils.
Pests and diseases	Apart from blight and root rots in poorly drained soils, other diseases are only of nuisance value. Blight can be controlled with copper sprays. No other compounds are yet registered for use. Puriri moth can cause damage to young trees by ringbarking. Walnuts are palatable to horses and sometimes to possums.
Shelter and Irrigation	Shelter is important, even in mild situations. Wind slows the growth down and cools the microclimate. Irrigation could be useful for very dry areas, especially during establishment. Don’t over water.
Payback Period	Grafted trees can start bearing after a year but an economic crop will not be achieved until at least 8 years under ideal conditions. Cropping is directly related to tree growth (and variety). The slower the growth, the longer the wait for nuts. As seedlings are generally more vigorous, they may be quicker to bear nuts

Got to the Walnut pages

---

Chestnut Chart

Species or hybrids between Castanea sativa, C. mollisima and C. crenata (Spanish, Chinese and Japanese)

Recommended Varieties	1002, 1005, 1015, Disk II, Mayrick King, Mayrick Queen
Climate	Not fussy, as long as they are clear of salt spray
Soil	Critical. Must be free draining down to 2 metres. Soil fertility not usually a problem.
Markets	Nuts mostly exported and local market is fully supplied, but expanding. Overseas markets pay highest prices for processing quality nuts, but this has not yet happened here. A recent development is the production of chestnut meal in NZ for the food industry. Chestnut timber is also highly sought after overseas. Timber from C sativa is naturally ground durable.
Harvesting	The nuts fall to the ground and must be harvested within a day to avoid deterioration. Prickly burrs present a problem. Various machines (vacuum and hedgehogs) available to pick up nuts
Post-Harvest	Chestnuts are starchy and taste rather like kumara. They can be dried for use like flour. Usually stored moist in cool stores. Processing into meal involves cooking and pressing
Orchard layout	Minimum spacing is 6×6 m. Some growers are allowing much more room. Chestnuts must not be thinned by cutting trees down. Dying roots would cause fungal infections in the remaining trees. (Therefore dig trees out). Most growers are planting 3 varieties. Harvest has to be by variety. Nut quality is modified by the pollinator.
Orchard Management	Very little is required except for mowing or spraying under the trees to enable easy nut collection.
Pests and diseases	Puriri moth, grass grub beetles, cicadas and opossums can cause serious damage on young trees. Very palatable to livestock. The fungus phomopsis affects storage of the nuts. At present no sprays are registered for use on chestnuts.
Shelter and Irrigation	Shelter is helpful in exposed situations. Irrigation can make establishment easier and increase crops. Both are important in severe climates.
Payback period	Grafted trees will start to bear after a year and should be giving an economic return by age 4. The pure Japanese varieties take a year or two longer.

Go to the Chestnut pages
← Back to Nuts

Wednesday, 27 August 2003 – Updated: 2015-02-20

Introduction

Pistachio (Pistachio vera) nuts are a crop of great antiquity.
They probably originated in Iran, Turkestan and Afghanistan.
The major producers of pistachio nuts are Iran, Turkey and California in the USA.
Less important producers are Australia, India, Pakistan, Afghanistan, Syria, Greece and Italy.

Orchard cultivation in America and Australia has a short history.
Of 40,000 acres planted in California, about 90% have been planted since 1970.
Australian interest also began in the 1970’s and they have made good progress especially on selecting cultivars suitable for Australian conditions.

The pistachio is a small tree similar to the fig in its straggly growth and large deciduous leaves.
Its natural habit is to branch at ground level and it is rare for a trunk to develop unless trained to do so.
The roots develop a long taproot making pistachios highly drought resistant.

They have separate male and female trees which rely on wind and air movement to achieve fertilisation.

Climatic requirements

Summers need to have 7 months growing period, frost free for 200 days, with hot and dry weather into the autumn (similar to the olive).
A daily maximum around 30°C is ideal.
A cold period is needed in winter to break dormancy.
Requirements suggested are about 1000 hours below 5-7.5°C.
They cannot tolerate excessive dampness and high humidity.

The flowering period ideally should be frost free. This will probably be about 15^th to 31^st October in NZ.
Individual flowers open for 5 days and the trees bloom for 10-15 days.
The lowest temperature during fruit set should be -3°C or fruitlets will abort.

Climate Summary of Major Pistachio Growing Areas

	Heat Summation Degree Days	Coldest Month Mean Monthly Maximum
Iran	3172	5°C
California (USA)	2200-2570	7°C
Merbein (Australia)	2060-2261	10°C

Soil preference

Pistachios will not tolerate wet feet for a prolonged period. Ideally soils should be deep, friable, well-drained, but have moisture retention. They are capable of surviving in poor, stony, calcareous, alkaline or slightly acid conditions. This makes them valuable trees for reclamation and conservation projects. Although they are tolerant of a range of soil pH, a pH between 7·1 – 7·8 is considered ideal.

Cultivars

Two cultivators are recommended for general use in California and Merbein

• Kerman – Female. Kernel above average in size. Shells split well and are easily opened by hand. Late blooming, biennial heavy producer. Liked for size, crispness and snap when eaten. Originated in California from seeds imported from Iran.

• Peters – Male. Good pollen producer.

• Sirora – open pollinated seedling of Red Aleppo that ripens earlier in Australia.

• Sfax – Female. Small nuts with high percentage of splits. Relatively low chilling needed. Pollinated by Peters. Grape like clusters easily harvested.

• Other Middle East cultivars are Bronte, Trabonella

Local experience will be vital to match the timing of pollen shed to female reception.

Rootstocks

Scion cultivars are budded onto seedling rootstocks. Because bare-rooted trees are difficult to transplant because of their dominant taproot, the sooner the young trees are in the field the better their establishment. This necessitates subsequent field-grafting that is quite difficult with often a poor percentage of takes.

P. vera is susceptible to nematodes so other Pistacia species are used as rootstock.
P. atlantica and P. terebinthus have good resistance to nematodes and soil-borne diseases and the main ones uses in Australia. However both are susceptible to Verticillium wilt, and in California P. intergerrima is now used where this disease is a problem.
P. terebinthus is the most cold-tolerant.

Seed Germination

Seeds may be planted soon after harvest. Scarification of seed shells speeds and increases germination. One method is to spread seeds in a damp "wettex" or towel and keep at 20°C. Germination begins in about 10 days. As seeds sprout they can be transferred to pots or root trainers. A long taproot lengthens quickly so they need putting into extra deep pots immediately. The main root turns black but this is quite normal.

Seeds can also be stratified for 2 or 3 months in a refrigerator in moist conditions.

Plant in permanent positions as soon as trees are large enough.
Protect them from rabbits.

Budding & Grafting

Use cold stored dormant wood. Budding in New Zealand is probably best done between October and December. Late winter grafting can be done in September/October for smaller numbers is you have plenty of budwood. Support new shoots so they don’t blow out in strong winds.

Rootstocks should be at lest 75-100cm high and 1-1.5cm thick at budding height. They should be in active growth at the time of budding.

Graftwood is collected mid-winter when the trees are dormant. Budwood can be collected at the same time or just before budding takes place.

The main hold-up is the difficulty of budding and grafting but some have been established in Marlborough so results are able to be seen.

Pollination

As female flowers are receptive for only about 4 days, male trees shedding pollen during the first half of female blooming period should be selected. Usually one male tree is planted to 8 female trees as a 3 x 3 block of females with a single male in the centre. Pollination occurs by wind or air drift, although bees may actually take quantities of pollen and thereby reduce fruit-set.

Orchard Establishment

The site should be sunny and windy. Soils need to be well drained and the pH range can be from 4.5 to 8.5, but 6.5 to 7 is ideal. Adequate water dramatically improves quality and yield so rainfall should be at least 400mm or irrigation needs to be available. However fertility should not be too high as excessive lush growth is not desired

A general spacing is 8 x 5m but this may be adjusted to suit your particular needs. Because tree growth is slow many orchards contain temporary filler trees for the first 10 years. Young trees start copping form year 4 or 5. Yields increase until 20 to 25 years.

Apple orchard fertiliser will be suitable. Pistachios often show Zinc and Boron deficiencies so regular leaf and soil tests will be needed to keep nutrition correct.

Tree training to develop a good framework is essential for the first 4 to 5 years. First develop a trunk about 1m high then train the main permanent branches. As resin oozes from pruning cuts only prune when absolutely necessary

Weed control is needed to reduce water competition and disease.

Diseases

Verticillium wilt causes branch die-back and may eventually kill the tree. P. verara is particularly susceptible.

Phytophthera parasitica attacks pistachios sited in poorly drained wet sites. Young seedlings may also suffer if kept too wet.

Armillaria mellea kills trees. Infection spreads from infected soils from previous infected trees

Harvesting

Unlike most other nuts pistachios need harvesting from the tree before they fall to the ground. This is because they quickly deteriorate thorough staining and fungal attacks if left on the ground. Aspergillus flavus and aflatoxin can be a problem wherever pistachio crops are grown.

Moisture content is often 40-50% when harvested so that hulls must be removed mechanically within 24 hours and then rapid drying to between 5-7% moisture is needed for safe storage.

Commercial crops are harvested with a tree shaker on to collecting sheets. When hand picking, the fruiting branches are picked off avoiding damage to the adjacent fertile buds for next year’s crop.

Processing

Pistachios are high in essential amino acids (25%), carbohydrates (16%) and oil (55%) Iranian and Italian nut retain some of their chlorophyll.

Pistachios are served principally as roasted salted nuts They can also be used in stuffing, cakes, candies, preserved in syrup and are popular in ice-cream. Slating the nuts may be done with quite simple equipment. Middle East nut shells are often coloured by a red vegetable dye.

Unlike other nuts, split nuts are good nuts when it comes to pistachios. Non-splits are largely immature and have an inferior flavour but can be used for oil. Splitting is caused because the shell stops growing in early summer but the kernel continues to grow until autumn forcing the shell apart.

Yields and economics

Trees usually begin bearing in the 4-5th year after budding, but an economic crop is not achieved until after year 7 or 8.
In California 8 -15 year old trees yield 2 to 8 kg of inshell nuts per tree giving 200 to 800kg/ha. 16 – 30 year old trees yield 8-30kg/tree (800 to 2400 kg/ha)
Adult trees average 11kg annually with an average yield of 1tonne/ha.
However pistachios are prone to biennial bearing with a heavy crop one year followed by little or no crop the next year.

Three kilos of unshelled nuts are equivalent to one kilo of shelled nuts, with most nuts marketed unshelled and salted.
Using data from 1991 and assuming an in-shell price of $4·00 to the grower, 100 ha of trees are required for an economically viable orchard.
At a higher price of $5·90/kg a 10 ha orchard could be viable.

Losses of 30% due to no split, empty and stained nuts should be allowed for.

A Future Industry in New Zealand

The pistachio’s reputation for climatic extremes has encouraged tree croppers in Central Otago and Marlborough to try establishing orchards.
The long, hot, dry summers and very cold winters of Central Otago most resemble the climate of the pistachio homelands.
Care is required to select sites with favourable microclimates reducing the risk of spring frosts.
The cold tolerant Pistacia terebinthus would appear the most appropriate rootstock to try.
There is no data at this stage to know if Kerman or Sirora will be suitable for New Zealand and it is highly likely they will not be, but they are at least growing.
New Zealand needs to develop its own cultivars.

A Marlborough grower has already cropped nuts so there is no doubt they can mature here.
There are some field trial plots in Nelson growing satisfactorily and others still in pots.
Other trees have been recorded as having fruited, somewhere in the North Island so it would be good to know exactly where they are. If you can help locate them we would be most grateful.
At last report Eastwoodhill had a big lonely female tree.

It seems that as well as Central Otago, Marlborough and Wairarapa other places may be worth a try. There is also a trial plot in the Bay of Plenty.

References

“Australian Nutgrower” September 1996

Cultivated Broad Leaved Trees & Shrubs, Krussman

Cornucopia 2, Stephen Facciola

Roy Hart Notes

 

Pistachio Action Group – There was interest in establishing a Pistachio Action Group and readers were invited to join and exchange their experiences of pistachio growing.

 

To help differentiate between the various pistachio species here is some additional information –

PISTACIA L. – Pistachio – ANACARDIACEAE

Deciduous or evergreen trees or shrubs;
flowers inconspicuous, without petals, dioecious, in lateral panicles;
male flowers with 3-5 short stamens and large anthers;
female flowers with a globose ovary, styles short, 3-incised;
fruit a drupe.
10 species in the Mediterranean region, Asia Minor, East Asia, North America, Texas, Mexico.
In its native areas this plant is often of great economic importance.

Pistacia chinensis (Chinese pistache, Huang-lien-mu)

Tree; Deciduous, rounded tree to over 20m high

Leaves: Even pinnate (occasionally odd), about 20cm long

Leaflets: 10-12, oval-lanceolate, long acuminate, asymmetrical, 5-8cm long, nearly sessile, glabrous. Red colour in Autumn.

Flowers: Clustered panicles near shoot tips. Males about 7cm long, females 14-21cm and looser.

Fruits: Peppercorn-sized, red at first then blue

Uses: Young shoots and leaves are eaten as a vegetable.
The nuts are roasted and eaten or used in confectionery.
Cultivated in China

Pistacia lentiscus

Shrub; Evergreen, 4-6m high, densely branched, twigs unpleasant smelling, warty, not pubescent

Leaves: Even pinnate

Leaflets: 8-10 narrow oblong to obovate, quite short acuminate, 2-4cm long, rachis winged

Fruits: Peppercorn sized, red then black

Uses A sweet liquorice flavoured resin, mastic, derived from the bark of the trunk, is chewed as a breath sweetener.
It is also used to flavour masticha liqueur, Turkish Delight, puddings, almond paste, cookies, Mabulsi cheese, cakes and candies.
The Romans used the fruits as an aromatic seasoning.
Seed kernels are the source of an edible oil, known as shina oil of Cyprus.
In Sardinia, wild boar and other meats are roasted over mastic wood so the smoke gives distinctive aroma and flavour. Canary Islands, Mediterranean region.

Pistacia terebinthus (Cyprus turpentine tree)

Shrub; Deciduous, often also a tree in its habitat, to 9m, twigs glabrous, pleasant smelling

Leaves: Glabrous, odd pinnate

Leaflets: 7-9, lanceolate-oblong, 3-6cm long, entire, very glossy, rachis not winged

Flowers: 5-15cm long panicles, greenish

Fruits: Oval rounded, 8mm long, red at first then brownish

Uses: The sweet, greenish seed kernels are eaten or pressed for their edible oil.
Immature fruits, along with their stems are preserved in vinegar and salt.
Known as astjaar, they are used as a relish to accompany wines served during dinner.
Young leaves are cooked and used as a vegetable. The fresh flowers are eaten.
Resin from the trunk is used in Iran as chewing gum. Mediterranean region.

Pistacia vera (True Pistachio)

Tree; Deciduous, small, 5m

Leaves: Long petioled, odd pinnate

Leaflets: 3-5 ovate to obovate, sessile, pubescent on both sides 3-6cm long

Flowers: 7-10cm erect but otherwise inconspicuous panicles

Fruit: ?

Uses: Nuts eaten raw, roasted and salted or used in confectionery, ice creams, cakes, cookies, pies, soups etc. They also yield a delicious, gourmet edible oil but due to the high price of the nuts it is not usually produced commercially. Also used for seasoning sausages such as zampone, saucisson de langue, and mortadella.
In Iran, the fruits are make into a flavourful marmalade.
Eastern Mediterranean to Southwest Asia, cultivated.

Pistacia atlantica (Mt Atlas pistache)

Uses: Turpentine flavoured fruits called gadum are eaten raw.
Excellent edible oil from the very small crushed nuts and used for pastries.
Seeds are also pounded with dates. Source of resin like mastic.
Also used as rootstock and as pollen source for P. vera.
Canary Islands, North Africa.

 

Compiled from notes by: Dhana Pillai, Alexandra, February 1999.
Technical Editor: Gail Newcomb. Updated July 1999.
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.

…Interested in knowing more? So are we! Join us…

Classification : CARYA – Hickory – JUGLANDACEAE

Pecan – Introduction

Pecan is considered one of the most valuable nut species.
The word ‘pecan’ means “a nut too hard to crack by hand”.
Its scientific name, Carya illinoensis is from karyon (an ancient Greek name for nut) and a Latinised version of Illinois (meaning the nut that grew in the territory occupied by the Illinois Indian tribe).
This member of the Hickory family originated in North America but Pecan trees have been growing in New Zealand for more than 100 years. The enthusiasm of Owen Long and others who worked with the early trials has no doubt helped create the recent upsurge in interest.

Climatic Requirements

Pecans can grow throughout NZ especially well throughout most of the North Island and the top of the South Island, though cultivars are available to suit most climates.
Some of the North American cultivars are now grown as far north as Ontario as well as in Hawaii. Our windy conditions however seem to mean large branches are often blown out. Therefore pecans should be grown in sheltered sites and for nut production the pecan will probably need our most favourable climates for warmth and shelter.
Approximately 150 to 210 frost free days are needed through the growing season for nut production. The rainfall ranges from 760mm – 2010mm with water needed to initiate nut growth , increase the size and to prevent nuts drying out and dropping prematurely.
Temperatures need to be warm enough to sustain an adequate growing season, with a chill spell during the winter dormancy. The pecan can stand heavy frosts when dormant, but late frosts prevent fruit setting and even kill fruit that has set. Thus a site with good air-drainage and a frost free period from the initial growth stage in spring until the nuts mature in autumn is required.

Relative humidity above 80% interferes with pollination by preventing the opening of the anthers. Leaf and nut diseases of pecans tend to be more severe where humidity is high.

The pecan grows best where average summer temperatures are within the 25°C to 30°C range with little difference between night and day temperatures. It has a definite cold requirement: 750 hours below 7°C has been suggested in overseas literature, but again there are definite clonal differences in this respect.

Cultivars

Of the more than a thousand cultivars of pecans over 40 are under evaluation in this country. At present cultivars have not been tested enough to make hard and fast recommendations. Some will most certainly suit specific regions better than others.

Other considerations are that with some cultivars the ripe nuts fall freely from the trees within a short time span. With others, the grower has to shake the trees to dislodge the nuts.

USA cultivars come from different climate zones so if you wish to grow pecans in NZ you should choose cultivars which originate in areas climatically similar to the area in which you wish to grow them. Here are the main climatic groupings and the cultivars which NZ has obtained from that source

Western Cultivars – Suited to a relatively hot dry climate (200-220 days above 12°C):Apache, Caddo, Cape Fear, Cherokee, Chickasaw, Choctaw, Shawnee, Shoshoni, Texas, Wichita, Sioux

Eastern Cultivars – Adapted to hot humid conditions (200 -220 days above 12°C):Candy, Desirable, Elliot, Western (Schley), Mahan, Mohawk

Northern Cultivars – Suited to a shorter growing season (160-180 gays above 12 C) – some even less:Chief, Colby, Giles, Giles Improved, Gra-Bohls, Gra-Tex, Hirschi, Peruque, Northern

From Further North – Short growing season and colder winters: Carlsen 3, Fritz, Kansas, Lucas, McElroy Rock, Bouer, Witte

From Israel – Croll

From Mexico(high elevation) – San Antoni

NZ seedling selections – trialed Northland, Pokeno, Gisborne: Keri,
Fisher A, Dr Sam

NZ Performance

The only indication of cultivars performing well are Mohawk in Gisborne and Apache doing reasonably well in Nelson. However considering the short time this assessment has been going on, nothing clear cut is indicated. Obviously a lot of patience is needed with this crop.

A sensible approach to cultivars however is for South Islanders to try the Northern cultivars and the warm sites in the North Island are more likely to suit some of the others.

Pollination

Pecans are wind-pollinated and cross pollination is important so this should be taken into account when planting out. Even in North America it is recommended to have at least four cultivars that are known to cross pollinate in an orchard, that is with similar leaf out/leaf falling times. One of these two cultivars should shed pollen before the emergence of their female flowers, and two should shed it after their female flowers.

All trees have both male and female flowers, (monoecious) but the male catkins rarely shed pollen when the female flowers are receptive.

The staminate flowers develop from axils of leaves of the previous season or from inner scales of the terminal buds at the base of the current growth.

The pistillate flowers appear in short spikes on peduncles terminating in shoots of the current year. Since two kinds of flowers are produced on the pecan, pistillate and staminate, the pollen must be transferred from the latter to the former so that pollination may take place.

The following list shows the known flowering characteristics in America –

Female flower receptive before Male pollen shed

Apache, Chicksaw, Choctaw, Shawnee, Shoshoni, Sioux, Tejas, Wichita, Candy, Elliot, Mahan, Mohawk, Colby, Gra-Bohls, Gra-Tex, Fritz and Lucas

Male pollen shed before female flowers receptive

Caddow Cherokee, Cape Fear, Cheyenne, Desirable, Western (Schley), Chief, Giles, Hirschi, Peruque, Northern, Carlson 3, McElroy, Rock, Witte

Others not listed are in the unknown category.

Soils

Pecan trees will grow in a wide variety of soils but do not like permanently wet sites. However it is not recommended to plant them in your best ground. In Israel they are reported to do well in heavy clay but reasonable drainage is still needed. As vegetative growth in New Zealand is often excessive, a less fertile soil is probably a good choice.

If the soil is poor, ie, shallow, poorly drained, tight with poor aeration, the management program, regardless of how good it is, cannot overcome such soil limitations. Trees can be grown on such soils but long term economical production is not feasible.

Site

Pecans are native to river and creek bottoms, the soils of which are deep, fertile and well-drained and have substantial water holding capacity. Pecans require at least 1m of well drained soil above the minimum depth of the water table to develop a strong root system. Pecans planted on shallow soils having poor internal drainage never develop into large, productive trees.

Once established pecans are able to tolerate deep, prolonged flooding for more than a year, or able to survive deep flooding for one growing season, with significant mortality occurring if flooding is repeated the following year. (Source: Whitlow and Harris 1979)

Water is critical to obtain full sized nuts, as well as to fill out the kernels. Water stress in mid-summer drastically impairs quality and reduces next season’s crop potential too.

Steep slopes will cause difficulties with harvest.

Nuts

Seedling pecans may not start bearing in worthwhile quantities until they are ten years old, but from then on yields increase annually.
Budded or grafted trees start bearing about 4-7 years after planting.
Some trees are alternate bearing.
Yields at maturity vary from 45-450kg/tree. The possible yield is 3 tonnes per hectare and a figure quoted was $2 per 100g.

Pecan nuts have smooth brown mottled shells with a greater proportion of kernel than walnut, and thinner partitions separating the two halves of the kernel.
Their shape varies from long cylindrical with a pointed apex, to short and roundish, with many intermediate forms.

Nuts should be symmetrical, large (no more than 110/kg) and with good kernel.
Kernel percentage varies but an average of 40% is considered satisfactory.

The kernel has a 78% fat content at 6200 calories per kilogram (compared with chestnuts at 4-5% fat and 2400 calories per kg)

Taking care of the nuts when they fall is important. Pecans last a long time, particularly when frozen and can hold their freshness for up to two years.
Store shelled or unshelled. Nuts in shell retain quality longer than shelled and large pieces store longer than tiny pieces.

Planting Seed

Pecans do not come true from seed, and every native or seedling pecan tree is distinctly different from the seed parent. Large nuts should be used as small nuts can lack vigour, and their reduced size may also be due to disease. Only large vigorous seedlings should be used for further propagation.

Seeds lose viability under warmed dry storage conditions therefore they should be stored at 0°C immediately after harvest until planted. Mid-winter planting with the seedlings emerging in spring seems to be the most successful timing.

It is relatively easy to grow seedlings for rootstock with a similar method to that used for walnuts. If the nuts have dried out, soak them in water for about five days before planting to improve germination.

Stratify seeds (cold treatment 1°C to 3°C) by placing the seeds in damp sphagnum or peat moss in a plastic bag in the bottom compartment of the household refrigerator for 8 to 12 weeks then as each seed shows signs of sprouting it should be remove and sown.

The kernel of pecans and similar nuts consists of two halves (cotyledons). Research overseas on the Persian walnut shows that the best planting position is horizontal with the plane of the suture line perpendicular to the soil surface.

Sow 2 to 5 cm deep in pots (PB10), nursery row or permanent position. Keep only the strongest straightest seedling. Avoid getting the taproot bent.

In the ground nuts should be planted at intervals of 20 to 30 cm at depth of 5-8 cm and in rows 2-3 m apart. Seedlings must be adequately watered at all times. A little nitrogen often assists growth.

Grow on to size needed for budding or grafting.

Planting Distances

Pecan trees have a very long life span and can attain a great size. However to increase their profitability in early years interplanting is advisable.

Initial planting may be on the square system 7.5m x 7.5m or 175 trees per hectare. Alternate diagonal rows are removed at the first thinning and then alternate rows for the second thinning. The remaining trees would be at 15m x 15m spacings.

Tree removal should be done when sunlight in the orchard floor does not reach 30-40% in the middle of the day (Malstrom, et al. 1982).

Immediately after planting trees should receive a thorough soaking with water and again a week later. Over irrigation of young tree can result in rotting of the roots.

An occasional check is necessary to see that no growth develops from below the scion. Remove it if it does. Animals should not be allowed in the paddock for at least three years after planting unless the trees are protected. Where it is intended to graze stock the stem should be trained to 2m free of side branches.

Planting Seedlings

These ungrafted trees make good landscape trees because they characteristically have strong, fast growth and a natural central leader without training.
Nut quality is variable but at least acceptable.
Seedlings usually are better in structure and appearance than improved variety trees.
Seedling trees rarely bear nuts as early as improved cultivars.
There are some seedling trees grown from Australian seed performing well.

Vegetative Propagation

Vegetative propagation of pecans is by budding or grafting selected cultivars onto seedling pecan rootstock as these bear much sooner than seedling trees. The rootstock can influence the performance of the scion.

Seedlings on one Hickory species, Carya aqautica, could be used on some of the wetter land bordering the Gisborne plains. Pecan scions will grow on Hickory trees but the nuts are usually somewhat smaller than nuts of the same variety from trees on pecan roots.

Leafy, softwood pecan cuttings will root under mist. Plants can also be propagated by root cuttings or trench and air layering.
Young seedlings are tender and should be shaded from bright sunlight.
Budding and grafting are exceptionally difficult, so if possible leave this to the Nursery. Ideal conditions for this are 26°C for 2 to 3 weeks – not possible outside in NZ – so a hot box as used for walnuts would be the thing to try.

Outside budding and grafting is a hit and miss affair, but if trying this, do it during the warmest part of the season, January/February.

To help the whole process make sure the rootstock is healthy and growing well. This can be achieved by watering well 2 weeks before budding and making sure the zinc and boron levels are good. (Trace element spray 2 months before)

Some success has been had with Four Flap Grafts, Shield Budding and Whip and Tongue grafting.

Budding

In the summer towards the end of the second growing season, or in early spring of the third growing season, the seedlings are large enough to bud to the desired cultivar.
Patch budding is the usual method. Current season buds are used in late summer and these buds are not forced until the following spring. Previous season buds, whether fresh or stored can be used for spring and early summer budding.
Stocks with buds that take early should be headed back that season. Special precautions are necessary to prevent drying out before callous formation takes place.

Grafting

An alternative method of producing the desired cultivar is by crown grafting (where the grafting is done at ground level) in late winter or early spring using the whip and tongue method. The seedling rootstock are whip-grafted shortly before and during the time that they start growth at the beginning of the second and third growing season.

Like the walnut, the pecan is not easy to bud or graft but the use of a grafting box with a constant temperature of 27°C for 3 weeks improves success.
Hygiene is important. The union should be wrapped with plastic budding tape and the cut end of the scion should be waxed.

After the new top grows for one or two seasons the nursery tree is ready to transplant to its permanent position. The long taproot necessitates very careful digging and replanting.

The Taproot

Pecans have a very long taproot and a spreading root system which may extend to about twice the spread of the tree. A two year old pecan tree can have a taproot over 1m in length. Once the taproot is well established lateral roots are produced.

The best soils for pecans are those which allow unimpeded growth of the taproot for at least 2m. Bare rooted planting can begin once the trees are fully dormant.
Young trees must be watered regularly until the taproot establishes.

Planting Trees

Prepare planting site by digging hole 45-60cm wide and 60-90cm deep. This is large enough for most seedlings.
Care should be taken to spread the roots so they are not matted together. All broken roots should be trimmed.
Add soil in small amounts at a time while carefully spreading other roots until the hole is filled.
Water the soil well to remove air pockets and firm the soil around the root system.
Do not fertilise at planting time.

Pecan mainly makes subterranean growth during its first year.

If conditions are at all harsh, newspaper etc can be tied to the tree about 15cm from the surface of the soil but leaving the top protruding. This cover is needed only for the first year.
This is important as the tree when planted has only enough sap to keep it alive. If the tree is not covered it can dry out during the 4-6 months it takes to establish. This in turn can lead to the stock (of no commercial value) growing and graft dying. This has been experienced in the Gisborne area.

Nutrient Feeding

Pecans require relatively high amounts of the major nutrients, compared for example to pasture. These nutrients are Nitrogen, Potassium, Phosphorus, Magnesium, Calcium, and Sulphur and are kept in the correct ratio by soil tests and leaf analysis and can be adjusted by the application of solid fertilisers.

Pecans also suffer badly from the lack of trace elements here in NZ where the soils are very different from their native USA. Trace elements in our experience are best applied to the foliage of most plants.
As pecans are unable to take up enough Zinc from the soil it is essential to use a balanced trace element spray as dictated by annual leaf analysis in conjunctions with soil tests. These need to be interpreted by someone familiar with the requirements of Pecans.

Most of our success in grafting and nut production can be attributed to the used of chelated trace element sprays. Chelates aid absorption through the leaves.
Americans list Zinc, Iron, Manganese, Boron, Copper, Molybdenum and Chlorine as essential trace elements, with emphasis on Zinc and Iron.

Our soils are high in Iron and Manganese (Woodhill) and while we have adequate levels of the other trace elements for pasture and stock health, these are only a fraction of the Pecan’s requirements.
Boron is not given any importance in the USA because their irrigation water is high in the element, but must be applied here for cell strength – ie breakages. It is also essential for a good nut set.

Because clovers supply much of the Nitrogen needed for good growth here in NZ foliar application of Nitrogen must be kept to lower levels than what is used in the USA.

We often have sufficient nitrogen in our soils so be sparing with this element if you get excessive shoot length though the growing season. US growers apply as a rule of thumb the 30/50 rule. If new shoots on an established tree are less them 30cm long then the tree needs more nitrogen. If the shoots are over 50cm the tree is getting too much.

Jung Wen Chiang M.A. manufacturer and importer of liquid and solid fertilisers has kindly offered his services interpreting solid and herbage tests in conjunction with Ron and Alison Ellett.

Pests & Diseases

We have few pests to worry pecans in NZ so spray programmes can be kept to a minimum unless a problem is encountered. Quarantine, so far, has kept problems out. Growers should therefore report anything suspicious to MAF whose phone numbers are in the Blue Pages of your phone directory.

Other problems are wind (broken branches), opossums, borers, shield bugs, bronze beetles and cicadas.

Eastern cultivars are adapted to more humid conditions and are less susceptible to Pecan scab (Fusicladium effustum) . While it is not established in this country the importance of trying to establish pecans without the disease must be stressed. Pecan scab is characterised by irregular brown to black spots on the leaves and circular spots on the nuts.

Reworking Trees

Named pecan cultivars arrived in New Zealand from the early 1970’s with more introduced in the 1980’s. It has become obvious through reasons of poor performance that a number of selections are not suitable for growing here because of low wind tolerance, poor flowering, low fruit set, incomplete nut filling, low kernel quality and small nut size.

It is beyond the scope of this fact sheet to discuss the merits or otherwise of specific cultivars because experiences differ from region to region. Growers with older trees may need to replace their poorest performers with their best producing trees.

The quickest way to increase production is to rework the existing trees rather than replant with new ones but make sure the pollinator trees are not removed.

Experiences of reworking larger trees up to 30cm in diameter has shown that inlay or bark grafting and summer patch budding do not give good end results.

Inlay or Bark Grafting using dormant wood stored for use during the current growing season can have initial high success rates but later prove disappointing. This is because using dormant wood which has been stored for several months increases the risk of infection. The large cuts are hard to seal, especially with the strong sap flow from the root system which increases exposure to summer pathogens.
These inlay grafts are very weak at the union and remain so for up to four years before the callous is large enough to buttress the subsequent growth.
You also need to continuously de-shoot the stock to force the grafts. This lessens the tree’s ability to recover at a time of the year when most of its reserves have moved into the top that you have just removed.

Summer Patch Budding is where unburst buds from the previous season are cut and patch budded onto smaller side limbs closer to the trunk, or on to younger trees. These can be forced a month later in January by cutting back to the bud but the same problems of large cuts in summer apply as outlined for inlay grafting.

Successful Reworking

If possible, patch bud into small side branches during late summer using the current season’s buds. Put at least two on each tree as a safeguard. Small side branches have tissue arising from within the main stem and are much stronger than shoots starting on the outside of the trunk.

If there are no suitable side branches, cut the tree off at shoulder height making the cut 40°from the horizontal so that the high side is to the prevailing wind. This should be done in the winter and sealed immediately with pruning paint. Nutrients coming up the trunk seem unable to translocate horizontally around a flat cut resulting in die back down the side of the trunk opposite the growing shoots.

During the following growing season select 3-4 shoots from near the top of the highest side and tie them together for mutual support as they grow. Patch bud two of these during February or March.

Cut back to the successful buds during the winter and remove the unwanted shoots. Keep one of the original shoots for rebudding if only one bud has taken. Cut this shoot back by half.

Staple or nail a flexible rod (fibre glass or PVC) to the trunk and loosely train the growing shoots up this. Select one shoot for the main leader and pinch the tip out of the second in January. The second can be used as a spare should the main one get damaged. Allow other shoots to grow from the base to remove some of the vigour from the new buds.

During the next winter cut the larger graft back by one third and the smaller back to 2-3 buds. Cut off long side branches. Remove any other rootstock regrowth. Loosen off the ties to allow for expansion during the following season.

During the second season ensure the ties are not too tight and remove any unwanted regrowth from the stock. Many buds will burst and grow including a number at the top. These will be spaced further apart than would have been the case had the tip not been pruned off. This makes sure that if one is damaged the others will not be weakened at the same point on the stem. Remove any breakages during the growing season, otherwise do not form prune until the following winter.

This subsequent winter pruning should see one leader left at the top of the tree with one third of its tip cut off. Potentially competing branches below this should be removed. Further down the stem where two branches arise, remove the uppermost one thus allowing a flatter angle to the remaining limbs. The ties and supporting rods should be able to be removed. Keep the spare bud until such time that you feel confident that it won’t be needed.

In the following years prune as per normal, removing narrow angled branches arising near each other on the main stem.

A reworked tree should show signs of nut production in the 3^rdor 4^thyears.

Seasonal Development

Pecan flowers from September to November about a week after the leaves have started to open. The nuts mature from March to April and fall March to June.

Market Potential

Pecans are a sought after nut and increasingly so in New Zealand. They are obviously a favourite with Americans but lesser known to other nations The USA production is increasing annually. Australians must have a greater appreciation for them as they are now producing their own.

New Zealand is a long way from producing enough nuts to make any impact, and there are not many plantings with significant yields.

The greatest concern with local production is the small size of the nuts. This should be improved and we need to find cultivars that will produce good yields of large nuts. This could be a young tree phenomenon and also with climatic changes this may alter.

Without a sample crop market potential remains unknown. We could speculate – but just that. Obviously pecans are quality nuts and if we can produce them the market should be there as overseas inventories are decreasing.

Timber

Apart from nut production, pecan timber could be another choice for pecans.
It is a valuable timber and good quality in this country.
Seedlings would be relatively easy to train for a straight trunk and this could minimise branch breakage. Twenty-five years has been mentioned as a possible timber harvest which easily matches pine growth.
The faster hardwoods grow the better the timber quality.
Pecan yields hard strong timber used for furniture, flooring and tool handles.
Also excellent source of firewood and BBQ or food smoking.

Erosion Control

As pecans have an invasive root system they could also be used for erosion control. This is being tested but no conclusions have been reached.

Contributors to this Fact Sheet:

Owen Long, Auckland

Paul Dodgshun, Gisborne

Alison Ellett, Helensville

References

Other sources NZ – G Halliwell, R Pollock.

Internet Sites – Universities in USA. There are many sites available with useful information and a searchable index of cultivars with some pictures.

Compiled by: Gail Newcomb, November 1998. Updated September 2000.
Privacy removals and proprietory format conversion – December 2007

 

Table of Pecan types and characteristics

Cultivars	First	Nuts Mature	Zone	Scab Resist
Apache	Flowers	Medium	Western	Susceptible
Caddo	Pollen	Medium	Eastern	Tolerant
Candy	Flowers	Early	Eastern	Tolerant
Cape Fear	Pollen		Western	Resistant
Carlsen 3	Pollen		Cool
Cherokee	Pollen		Western
Cheyenne	Pollen	Early	Western
Chickasaw	Flowers		Western
Chief	Pollen		Northern
Choctaw	Flowers	Medium	Western	Susceptible
Colby	Flowers	Early	Northern	Probably
Croll	Pollen		Israel
Desirable	Pollen	Medium	Eastern	Probably
Dr Sam			NZ Selection
Elliot	Flowers	Medium	Eastern	Resistant
Fisher A			NZ selection
Fritz	Flowers	Early	Cool	Probably
Giles	Pollen	Medium	Northern	Probably
Giles Improved			Northern
Gra-Bohls	Flowers		Northern
Gra-Tex	Flowers		Northern
Hirschi	Pollen		Northern
Kansas			Cool
Keri			NZ selection
Lucas	Flowers		Cool
Mahan	Flowers	Early	Eastern	Susceptible
McElroy Rock	Pollen		Cool
Mohawk	Flowers	Early	Eastern	Susceptible
Northern	Pollen		Northern
Peruque	Pollen	Early	Northern	Probably
San Antoni			Mexico
Shawnee	Flowers	Medium	Western
Shoshoni	Flowers	Early	Western
Sioux	Flowers	Medium	Western	Susceptible
Souer			Cool
Tejas	Flowers		Western	Susceptible
Western (Schley)	Pollen	Medium	Eastern	Susceptible
Wichita	Flowers	Medium	Western	Susceptible
Witte	Pollen	Early	Cool	Probably

 

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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Classification – Proteaceae

Introduction – Macadamia

Although Macadamia are native to the eastern subtropical coastal rainforest of Australia (23 – 29 degrees South latitude) until recently the main commercial plantings were all in Hawaii. They were used there for reforestation projects but were not satisfactory for this use. Many trees were planted as ornamentals and these formed the nucleus for the early orchard plantings until in 1936 the University of Hawaii began a survey from which the five most promising selections were named in 1948.

Overseas, major plantings exist in Australia, Hawaii, California, Florida, South Africa, Central America and Brazil with Australia now overtaking USA as the largest producer, with yet more plantations yet to come into full production. At last Australia is regaining control of the only commercial food crop native to it.

Macadamia nuts have been grown in New Zealand since 1875, with the first seedling orchard planted at Kerikeri by Mr Jolly in 1932. Not until the early 1970’s were the first variety trials planted in NZ Areas capable of producing quality macadamia nuts are limited by temperature and soil requirements.

Fredrich Wilhelm Leichardt, a German explorer of Australia collected the first specimen in 1843 but it stayed in the herbarium without identification or description for many years. Then in 1857 botanists Hill and von Mueller collected specimens and the genus Macadamia named after Sir John Macadam, a chemist, and the specific ternifolia was given. Years later it was found that the earlier specimen was the same. In 1952 a new species of Macadamia was described from the Celebes but 2 years later L Johnson an Australian botanist recognised the form as occurring in NSW to be a distinct species and gave it the name M. tetraphylla. Another Australian botanist, Lindsay Smith, decided M. integrifolia should have specific rank in 1956. With all the additions, subtraction and transfers finally resolved, the genus Macadamia at present comprises ten species. Other related species are, Banksia, Grevillia and NZ Rewa rewa, while a few others including Gevuina avellana have nuts that are sweet and edible without any processing.

The two main species, M. integrifolia and M. tetraphylla will also produce natural hybrids which can be taken advantage of to produce a wider range of fruiting variations. It is therefore important before deciding which cultivars to grow to first decide on your end use. On average about 30% of the nut weight as kernel is recovered, the remaining is 70% shell and waste but can be used to mulch the trees.

The tree

Large spreading evergreen trees range in heights of 12m for M. tetraphylla and 21m for M. integrifolia, though they are usually pruned for ease of orchard management. Tree shape is variable – umbrella, columnar, pyramidal or broad depending on cultivar. Bark is rough and brown. Roots are proteoid and it is this development which seems to relate to the vigour of seedlings as they increase the surface area of the root system for maximum nutrition absorption.

Macadamias are not fast growing trees overall but moderately fast the first four or five years. When they start bearing good crops the growth goes towards nut production rather than to vegetative growth. Most trees start bearing in three to five years. The length of time it takes is not related to production at a later age. Trees mature at different ages in different areas. Alternate bearing is common in Macadamias.

The two species are easily distinguished by their leaves and flowers.

• M. integrifolia leaves are obovate, leathery, glossy in whorls of 3, margins are entire with few spines, pale green new growth and 20-27cm in length. Flowers are creamy-yellow

• M. tetraphylla leaves are long and narrow in whorls of 4, spiny and often sessile, bronzy-pink new growth, then dark green and up to 50 cm long. Flowers are pink to light reddish-brown

However, between these two distinct types there are numerous intermediate forms varying in spininess of leaves, colour of flowers, size of nut and thickness of shell.

Climatic requirements

Being native to the rain forest of southern Queensland they grow best along the coast under conditions of high humidity and comparatively heavy rainfall. Crop yields seem to be correlated with spring rainfall and 1600mm falling predominately during summer but spread throughout the year is needed. Young trees need more water than mature ones and this can be regulated by irrigation.

In general, the trees produce a deep taproot and relatively few lateral roots therefore need the protection of windbreaks in exposed situations. Branches are brittle so acute branch angles on some cultivars are a problem. Cold winds can also affect growth.

In NZ they grow successfully in coastal areas of Northland, Auckland, Bay of Plenty, Taranaki, Nelson and Marlborough. Recent plantings are tending to be in the Central BOP and Eastern BOP where there are deep sandy soils and favourable spring blossom conditions which favour heavier yields.

Good growth is obtained between 20-25°C or where a mean summer temperature of 25°C is obtainable. Below 18°C growth is retarded and ceases below 10 or above 30°C.

Young trees (up to 2-3) are also frost prone so avoid frost pockets. Mature trees will tolerate 2-3°C frost while dormant trees can survive minus 7°C for short periods but flower clusters may be damaged by then. Protect trunks of young trees from frost by wrapping with cardboard or foil.

Mature Macadamias can withstand drought but crop will be affected.

Adequate watering is required during nut set to nut filling, during oil accumulation and including late summer vegetative flush. Trees should not be under stress at any time but especially mid-summer.

Soil

Macadamias are not as demanding as avocados in their soil requirements, but are more demanding than citrus. The soil should be fairly well drained but need be only moderate depth due to the shallow root system. On heavy clay soils the tree will often be chlorotic with somewhat stunted leaves and growth.

Best pH levels are 5.5 to 6.5. They will not tolerate soil or water with high salt concentrations

Slopes steeper that 1 in 25 should be planted on the contour with every precaution taken to prevent soil erosion. An ideal site would have free-draining deep sandy or volcanic soil, lying to the north with a 10 degree slope to catch more of the day’s heat and allow cold air to drain off.

Planting

Planting is usually done in autumn or spring but can be done with care during warmer months. The availability of trees seems to control the decision. The young trees are very susceptible to damage and water stress. Make sure the root system makes contact with the soil. Some potting mixes may impede water movement so remove some, put tree in hole, fill with water then top up with remaining soil.

Place scion side towards wind to prevent new growth being levered off.

Spacing of 6m X 6m is a recommendation. Don’t forget headings.

Fertiliser

Three to four balanced fertiliser applications are need in one season amounting to 5kg per annum for a 10 year old tree. Macadamias appear to be sensitive to a number of trace element deficiencies. Soil and leaf analysis can be done and fertiliser applied according to results. For the small orchard any citrus fertiliser is suitable.

Iron deficiency can be identified in the field by interveinal chlorosis. The major cause is overliming or a high pH soil and a high phosphorus content.

In some orchards foliar sprays of zinc, boron and copper are used regularly as NZ soils are often low especially in boron

Flowers & Pollination

Flowers are borne on long narrow racemes arising from the axils of leaves or the scars of fallen leaves. A raceme is a flower cluster in which, up to 500 flowers each with its own pedicel, is spaced along an axis. The proximal flowers bloom first They may be borne on the new growth if it is mature, but more often on the two or three season’s growth preceding the most recently matured flushed. The flowers, about 1 to 2cm long, are perfect (have male and female parts) but incomplete (no real petals), but four petaloid sepals. The flowers are carried on the inside of the tree on mature wood from four seasons to the current. Flower distribution follows the canopy outward.

• M. integrifolia has creamy white flowers in cluster of 15-30cm long, flowers from June to March though some strains year round

• M. tetraphylla are usually pink (can be cream) and in clusters up to 39cm long, flower August to October and produce one main crop

Hybrids can have either – pink from a recessive gene?

They can self pollinate but as varieties vary from being self-compatible to self-sterile the correct pollinators are required for good crops. Only 1-2% of flowers set fruit. Bees are the apparent major factor in pollination as well as leaf roller moth.

The pollen is shed within the flower 1 to 2 days before it opens, then 1-2 hours before opening, at about 7 – 8 am, the sepals curl back exposing the anthers closed over the tip of the style. Then the anthers separate and 5 to 10 minutes later the style breaks free and straightens, but its stigma does not become receptive until some time later. The minuteness of the stigma (capable of receiving only 10 to 12 grains of pollen) indicates that wind is not a factor in pollen transfer. The pollen of a specific flower is generally removed by insects before the stigma is receptive so pollen must come from another flower.

Good pollination improves nut yield, nut size, kernel recovery and quality. Insufficient cross-pollination may reduce potential yields to 10%. Such trees without a worthwhile crop-loading grow vigorously, shading out flowers and light. It becomes a vicious circle.

No planting should be made without providing for cross-pollination between the cultivars.

Three selected cultivars are recommended as a minimum number, with the different cultivars in separate rows, eg one row A4, one row GT 207, one row PA 39, with the pattern repeated.

The main flowering time in NZ is early spring – October and weather at this time has an impact on crop set. A number of growth flushes can be expected especially in warm areas.

Nuts

The fruit produced is a one-seeded follicle consisting of three major parts. An outer green smooth skin or husk surrounds the shell of the nut proper. The husk is the fibrous wall of the ovary and inside is the seed. The shell is the very hard outer seed coat. Inside the shell is the embryo or nutmeat kernel.

Shells of M. Integrifolia are spherical and generally almost smooth. The colour is brown and often with a lighter mottling.

M. tetraphylla are ellipsoidal, almost football shaped. The surface varies from slightly rough to very coarse or pebbled.

Shell thickness varies from paper-thin to more than 5mm. Opinion exists that altitude and exposure to ultraviolet light affect thickness but it is more probably genetic variation. This is not to say shell thickening cannot be induced as happened in Hawaii where a drought caused shell thickening in orchards without irrigation, and smaller nutmeats.

Thick and thin shells have good points. Thick shells usually have less nutmeat but more protection to the quality until shelled; they crack well in mechanised cracking machines.

Thin shelled nuts are assumed to be easier to enter – for insects and rats etc as well as humans. Thin shells often split open and the nutmeat oxidises. They tend to squash in mechanised cracking machines

The nuts start to mature six to seven months after blossoming and must be allowed to ripen on the tree. They are full size before this but you can tell when nuts are mature by the brown colour of the husk lining.

Nuts that do not drop naturally are referred to as stick-tights, and these sometimes open and pregerminate while still attached to the tree which makes the nutmeat inedible (cyanogenic and bitter).

Cultivars with thin shelled nuts are particularly suitable for table purposes when sold in the shell.. These yield over 40% by weight of kernel and can be cracked fairly easily.

Cultivars with moderately-sized medium to thick shelled nuts can be used for both processing and table purposes .Those with a medium to thick shell, which is too large for processing, may meet the requirement of some consumers

Harvest

M. integrifolia trees have long harvest season, often over six months and some are ever bearing dropping nuts throughout the years.

M. tetraphylla, especially the red ones, have a much shorter harvest season which in some cultivars can be as short as 6 to 8 weeks.

Nuts are harvested by picking either by hand or machine (overseas) or gathered from the ground when they fall. Nuts that drop should be gathered regularly to prevent damage by fungi or rodents.

Integrifolia cultivars generally have hulls which adhere tightly to the shell whereas most tetraphyllas split open.

Keep ground under trees clean at harvest or use a tarp cover on which the nuts can drop or be picked onto.

Picking starts in June (for some cultivars, notably Beaumont) in NZ and continues throughout the year with a break during pollination in October. Don’t pick in rain are nuts will be holding too much moisture.

Nut storage after harvest

Nuts must have their green husks removed within 24 hours of harvesting. Locally built huskers with electric motors or PTO (power-take-off) from tractors are available as well as some overseas models.

The objective of storage and processing is to produce kernels that are crisp, light brown in colour and free from blemishes. Inadequate drying and poor storage produce rancidity and off-flavour. Low moisture content must be maintained throughout storage.

Nuts can be stored at 1-2% kernel moisture for 12 months and still produce kernels equal to that of the roasted kernels prepared from freshly harvested nuts. (Cavaletto et al 1968)

Storage of high moisture nuts is not desirable and nuts stored even at 3.8% kernel moisture have a reduced shelf life.

Propagation

Fresh Macadamia seed germinates in two to four weeks if it has not been allowed to dry out. Remove the hull taking care not to damage the shell (may inhibit germination and make susceptible to fungi infection) and plant at once in suitable medium. Use seeds than sink in water. The percentage of germination is reduced by storage but the dry nuts may retain viability for two to three months but need to be soaked in water for 2-4 days. Plant with white spot facing down at depth of 2.5-3cm in PB10’s for ease of handling. A shallow fibrous mat of roots develop first then the tap-rooting system. Keep seed bags in shade at temperature of 21°C. As soon as growth starts the root will push into the soil to a depth of 10-25cm before any visible growth appears above ground in one or two months. If using a seedbed transplant when they have a pair of leaves and are 7-10 cm high. Leave the two cotyledons adhering to the stem as they contain food reserves. After 2-3 years the trees are a size to be grafted. Tetraphylla seedlings usually reach this before integrifolia.

Rapid healing of the graft union is aided if rootstock has growth checked prior to grafting by suppressing water or nitrogen to allow carbohydrate accumulation.

Scion wood should have been prepared by girdling (removing ring of bark and cambium 2.5cm wide) selected branches on mother tree 6-8 weeks earlier to increase carbohydrate content. Select budwood about 1cm diameter with ripe wood (about two years old and grey coloured). If scion wood to be kept, wrap and keep at 6°C

Whip, side-wedge or top graft in early spring or late autumn. Keep graft moist until established.

Cuttings may also be grown though some cultivars root easier than others. Take cuttings just before new flush of growth has completely hardened. Prepare by making sharp cut just below whorl of leaves but leaving two leaves at tip. Soak or dip in hormone and place in sterile sand or vermiculite cutting bed. Maintain high humidity. Bottom heat of 24^o C speeds callusing and subsequent rooting. Ensure there is enough depth for the new taproot to develop. Earlier trials with this method have seemingly failed because of this. M. tetraphylla cuttings root more readily than M. integrifolia

Larger trees can be successfully grafted or ‘ top worked’.

There can be graft incompatibility between the species which sometimes does not show up till the trees are larger.

Trees will grow from seed but will take longer to bear and the nuts can be variable.

Rootstock

It has been said that M. tetraphylla used as a rootstock of integrifolia varieties produce crop quicker. This is correct initially, however yield of cultivars grafted on to integrifolia rootstock perform better on a long-term basis.

Earlier it was believed that tetraphylla rootstock was more disease resistant to Phytophthora cinnamomi, however this is not normally a problem in well drained soil and the most usual form of the disease is trunk canker above ground level, usually due to bark damage.

Nearly all the early plantings in Hawaii were on tetraphylla rootstock and they are the ones that are now seriously affected with “dieback”. They are now doing a major replanting program to replace these trees using integrifolia rootstock.

One of the problems long term may be incompatibility between rootstock and scion which can take a long time to show up, also although tetraphylla grow faster initially, they finish up as smaller trees and used as rootstock may not be able to support the large canopy on top.

Macadamia doesn’t have a single deep taproot as a mature tree, but like many rainforest trees, they put down a series of tap roots as they tend to feed more on the litter from the forest floor.

In California the industry is based on tetraphylla varieties on tetraphylla rootstock.

South Africa used largely Beaumont (hybrid) clonal rootstock which is very vigorous and produces even cuttings with a good root system.

Early NSW plantings were largely Renown rootstock. It is a hybrid and heterozygous in respect to the degree of diversity in the genotypes. Most of the later plantings in Eastern Australia have been on H2 (Hinde) rootstock, which is homozygous, and most of the progeny are vigorous and fairly true to type.

Tree Training

Some pruning and training is required for the Hedgerow System of growing. After planting, the trees are cut back to 60cm above the ground if they are branched. In the following years retain a central leader and to give greater strength space branches on a spiral system with 20 – 30cm between. The first branches are at 60cm above the ground.

Pruning Strategies

There are three reasons for pruning macadamias. These are in the order of orchard development and priority.

1. Prune for good form and light in the lower branches

2. Prune according to the access you will require to pick

3. Prune to manage overall height of the trees

To achieve this there are specific recommendations as to which branches and trunks to remove. A desired tree shape can define this, but since there is such huge variation in tree form between cultivars it is good to have guidelines for relationships between branches and prune a tree on its individual merits. The principal rule is to maximise the angle between branches and the trunk.

For More Light:

1. Remove up to 60% of the branches evenly around a multiple fork starting with one of the strong vertical branches. Leave a leader plus one or two branches, more for younger trees.

2. Remove the upper branch of two that overlap.

3. Remove one of two branches that cross over if it is not possible to untangle them.

For Picking Access

1. Remove up to two branches on each side, at shoulder height and below, that project into the row to create one or two picking bays on each side as required. Or trial a shape suitable to the picking method used.

2. Remove damaged or dead branches close to the trunk.

For Height Maintenance

1. Remove or reduce the height of one leader (or both) of a weak fork.

2. Reduce the height of long whip-like leaders at half a metre above the last branch.

Pruning is a positive action for the management of intensive macadamia plantations. Intensively planted orchards, as found in New Zealand require a pruning regime that suits the spacing of each orchard. The exact strategy is an individual decision for the orchard manager to make for each situation, but what is not obvious is that routine pruning ‘a little and often’ is required for sound orchard management.

For orchard hygiene and ease of mowing and spraying all the skirts on the trees need to be trimmed off.

Weed & Pest control

Pest and disease control for trees in production normally requires 2-3 spray applications per year, depending on location. It is important not to overspray the orchard and kill the leaf roller moth because that is considered an important pollinator for macadamias.

At blossom time apply the fungicide Rovral WP at 150 g/100 litres of water and BT(Bacillus thuringiensis) at 50 g/100 litres of water.

Further insecticides may be necessary in January-April to control green vegetable bug (also known as shield bug or ‘stink-bug’). This insect is a worldwide problem as it can pierce the nut, staining the kernel and affecting the flavour rendering it unsaleable. Endosulfan applied at 200 mls/100 litres of water is the usual control. Recently 60% of a crop was lost to this bug. Trials are underway to find a way to control them, especially organically.

Regular mowing is important to keep bugs moving off rubbish on to the ground and to stop rats building nests in the ground.

Rat control is most important and bait stations near the water supply will keep rat numbers down and stop them chewing through too many shells. Also remove any old birds nests or the rats can fill these with nuts and never need to come down to the ground. Rats start eating macadamias from about January 20 every year which gives them five months to take your crop before you begin harvest. Small orchards, if poorly managed can lose all their crop to rats.

Cicadas cause damage to young branches.

Yields

The top orchards in New Zealand, under good management, have returned similar yields to the best overseas, ie 4-6 tonnes per hectare. On good sites production of PA 39 at 20kgs per tree can be achieved from year ten onwards. Poorer sites may return 1-4 tonnes per hectare. Sometimes when trees start cropping heavily their nutrition requirements are not met leading to a decline in yields.

Different areas are finding cultivars that perform better in their climate and the best cultivar for NZ conditions is yet to be established.

Oil Content & Quality

Tetraphylla nuts generally have less oil but more sugar than integrifolia nuts therefore are sweeter to the taste.

Quality has long been associated with oil content. A rapid method of oil content determination can be made by using the flotation method based on specific gravity. Ordinary tap water has a specific gravity of about 1.00 and nuts that float in it have an oil content of 72% or more and the kernels are considered to be Grade 1. A salt solution containing 5 1/2 oz salt in a gallon of water has a specific gravity of 1.025 and nut that float in this denser medium have an oil content between 67% and 72% and are Grade 2, Nuts that sink in this solution have oil content less than 67% and are Grade 3 or culls. They are also often misshapen, discoloured, shrunken in size, poor flavour and have tough leathery texture.

Grade 1 nuts are usually roasted and salted or flavoured and sold as desert nuts.

Grade 2 can be slivered and used as toppings or in ice-cream.

Grade 3 may be used in cooking.

For eating the kernel should be white to light cream in colour, crisp in texture, with no off-flavour.

Processing

Nuts must be dried to reduce kernel moisture to 1.5% or lower before roasting. During the drying process the kernels shrink slightly and most free themselves from their shells. The separation of kernel for shell is essential if the nuts are to be cracked without damaging the kernel. A percentage of kernels that stick to the shell occurs in most macadamias. Drying temperatures are critical.

• Stage 1: Circulate air at ambient temperatures or warmed air, ideally below 30^oC and certainly no more than 36^oC. It takes five to seven days to bring kernel moisture below 12%.

• Stage 2: In NZ nuts are usually kept in onion sacks holding about 5 kgs of nuts in shell. These are placed on shelves in an insulated container or silo and a heat pump running at 52^oC is used for 5-7 days. The final drying time depends on the initial moisture content of the nuts, dryer design and efficiency, and air velocity. Kernel moisture should be 1.5% or less after drying at which point the nuts are ready for cracking. However there is an increasing practice overseas to crack nuts at 3.5% to 5% moisture to reduce kernel damage during cracking and to reduce power bills for the final drying stage of the kernels.

• Nut cracking: Recent nut crackers are based on the ‘Shaw Cracker’ with vee-design chambers and a rotatable wheel with radially arranged cutting blades which can crack a range of sizes at the same time. Large-scale processors have a cracker for each size of nut. Most processors pre-grade nuts to prevent damage to the kernel during cracking

• Shell separation: Shell separation is usually achieved by rotating screens, air separation, hand separation and electronic colour sorting or a combination of these.

• Roasting: The nuts are either oil roasted or dry roasted at 132^oC for ten to fifteen minutes until a golden brown colour and delicate aroma are achieved.

• Packaging: Most macadamias are packaged in laminated foil packs either under vacuum or with a nitrogen flush to remove oxygen

Nutritional

Macadamia nuts contain no cholesterol and in clinical tests they have been shown to lower blood cholesterol (by 7% in four weeks) if eaten regularly and in moderation (6-20 nuts daily) thus actively reducing the risk of heart disease. The protein is low in lysine and high in arginine, which can decrease the aggregation of platelets (reducing clotting and thrombosis), and improving relaxation of veins.

Uses

The kernel is the main product from the macadamia nut tree. After harvesting, the husks covering the nuts are removed. The nuts are fried, the shells are cracked, and the kernels are removed to be oil-roasted or dry-roasted. Kernels are commonly sold as snack nuts and chocolate-covered candy. Ice cream manufacturers and the baking industry also use macadamia kernels as an ingredient. A recent development is the manufacture of ‘Macadamia Nut Butter’ which is easily eaten by those who cannot manage the whole nuts.

Shells and husks can be used as a mulch, fuel for processing macadamia nuts, planting medium, plastic manufacture and as a substitute for sand in the sand-blasting process. Macadamia oil is used in cooking as well as being a safe oil for all skin types, especially those damaged or scarred. It has a high Vitamin E content so used in the cosmetic industry.

M. integrifolia: The sweet delicious nuts are eaten raw, roasted, fried, coated with chocolate or carob. Macadamia nut oil contains 80% monounsaturated fats and only 8% omega-6 fatty acids – used to add subtle nutty flavour to stir fries and salads

M. tetraphylla: Nuts eaten raw, roasted, fried and used in cooking and baking. Sweeter.

Hybrids: in subtropical areas these appear to be better producers of quality nutmeats than either of the two parents.

Markets

Because of our present small production, and since it is a ‘Tourist’ nut with added value for confectionery, it is estimated that the local market will be worth $5,000,000. Small processors currently in the industry say they have more problems sorting nuts than selling them. The world market demands high-quality macadamias with an oil content higher than 74%. Nuts with a lower oil content are too dark in colour when roasted, and become chewy rather than crisp.

It has been suggested that by growing the same quality nuts as Hawaii and Australia then marketing and selling overseas will be easier as they have spent money developing the markets which we can then sell into.

Work has already been done in this field by the NZ Macadamia Society and NZ Macadamia Nut Growers Co-operative Co Ltd. Other growers are establishing their own processing equipment and often buy in nuts from smaller orchards

Macadamia nut production and exports continue to grow due to strong international demand. Macadamia exports by selected countries in 1997/98 are forecast to increase 9 percent to 39,335 metric tons (in-shell basis). Australia remains the world’s largest exporter of macadamias, accounting for more than 40 percent of the world total. Kenya ranks as the second largest exporter of macadamias, and the United States third.

Cultivars

• A4

(AU – Henry Bell, 1980 PVR Renown OP) Early bearer at age 3; spreading tree; large early crops. Open, dainty spreading tree with small prickly light green leaves. Creamy, good large uniform shape nuts with dark brown smooth shell. Holds nuts under stress. Excellent crop of mainly closed husks. Singles wide spread Harvest July to late September. Wind tender, prolific feeder. Kernel recovery 43- 46.9%.

• A29

(AU – Henry Bell, 1981 PVR Haes OP) Early bearer at 3-4 years, Upright medium tree with good bunches mainly internal. Long prickly dark green leaves. White, good medium uniform shape nuts with dark brown shiny smooth shell. Drop clean with good crop of mainly open husks. Harvest June to late July. Kernel recovery 40.14-40.74%.

• A38

(AU Henry Bell, 1981 Own Choice OP) Bears 4 years from planting. Upright tall strong tree smooth leaves. Creamy medium uniform nuts with dark brown shell. Drop clean with some holding. Big bunches mainly internal. Excellent crop of mainly open husks. Long harvest from September to November. Kernel recovery 38.76-38.83%.

• A104

(AU – Henry Bell, 1983 PVR Renown OP) Bears 3-4 years. Upright gangly tree with medium light green smooth leaves. Creamy, very round small nut with fawny smooth shell, drops clean. Bunches mainly internal. Good crop of mainly open husks. Short harvest season early July to late August. Kernel recovery 44.11-45%.

• A217

(AU – Henry Bell 1987) Crops 3-4 years from planting. Open spreading short tree with big long dark prickly leaves. White large nuts with light brown smooth shell. Most drop. Heavy cropper with open husks. Singles widespread. Long harvest from July to late October. Kernell recovery 34.5%.

• A268

(AU -Henry Bell) 1987 Haes 344 OP) Crops 3-4 years from planting. Open spreading strong tree. White large nuts with light brown prickly shell drop clean. Singles and bunches wide spread. Heavy crops mainly open husks harvest later June to August. Kernel recovery 37.25-39.12%.

• Beaumont

(Dr JH Beaumont – Au)M.x sp. Round, medium to large nut, 65-80 per lb; shell medium thick; kernel 40% of nut with high percent grade A; texture and flavour good. Nuts picked over long period. Drying problem as kernel stick to shell on one side if not turned. Tree upright; ornamental; new leaves reddish; flowers bright pink. (Not high rainfall areas and debatable if best in NZ) Good crops with Nelmac 2 pollinator

• Elimbah

(Au) M. tetraphylla. Medium to large nut: shell medium brown, rough, thick; kernel averages 40% of nut, quality high, flavour excellent, ripens late, harvested over 6-8 months. Nuts drop.

• G5

Good pollinator

• GT1

(NZ – Ian Gordon) Good pollinator Beaumont. Crops 1 month after Beaumont

• GT201

(NZ – Ian Gordon) Improved GT1 with better tree shape

• GT207

(NZ – Ian Gordon) Drops nuts well but has tendency to twinning. Not a problem if cracker handles them.

• Ikaika

(HW) M. integrifolia Bushy vigorous tree; medium sized nuts; medium thick shells; early ripening; reliable crop (Bay of Islands no 3)

• Jordan

Sometimes glutinous kernel; thick shell; early bearing heavy crop

• Kakea

(HW) M. integrifolia Large nuts; excellent flavour; medium thick shell; productive, cold tolerant; upright tree.

• Kau

(HW) M. integrifolia Medium-sized nut, 60-70 per lb: kernel weight 36-40%, 95% grade 1; nuts drop May to June; upright tree, well formed ascending branches. (Bay of Islands no 2)

• Keaau

(HW) M. integrifolia Small nuts; excellent flavour; thin shelled; upright tree

• Keauhou

(HW) M. integrifolia Medium to large nut, about 54 per lb; shell slightly pebbled, medium-thick; kernel 37-40%, quality varies upon location. Crop matures over 3 months. Tree vigorous, spreading.

• Makai

(HW) M. integrifolia Large, uniform nuts, high quality. About 90 per lb: 40% kernel. Medium thick shell. Kernel quality excellent after cooking. Broad spreading tree.

• Mauku

(HW) M. integrifolia Medium sized nuts, average flavour, cold tolerant. Upright tree; nuts drop mid-May to end-June (Bay of Islands no 1)

• N7/N3 (Maroochy)

(AU) M. tetraphylla Very heavy cropper; thin shelled; high sugar; not for roasting; good pollinator Beaumont;

• Nelmac 1

(SA) nut slightly elliptical; thick shell; high quality kernel; bland taste; high oil; late flowering; drops nuts; light cropper

• Nelmac 2

(SA)large nut; open micropyle (hole in shell); high crackout; 22 kg; pollinate Beaumont; susceptible iron chlorosis ; Good in Pukekohe and East Coast

• Nutty Glen

(AU Hybrid) Large good quality nut

• Own choice

(AU) Good bearer in Pukekohe

Flowers and sets nuts year round in Bay of Islands. Susceptible to botrytis

• PA 39

(Brian Piper) High producing crackout 40%; 95% grade 1 kernels; drops nuts; tree small compact, very prickly; very susceptible green shield bug. Some places crops 1 month before Beaumont but in BOP good pollinator.

• Rangataua

(NZ – Hans Lens) Thin shelled.

• Renown

(Hybrid) Very large nut; elliptical; good for home use; difficult to put through shelling machine;33% crackout; 17kg; drops nuts

References & other reading:

Macadamias in NZ, Ian Gordon, Macadamia Management Ltd

Pruning Strategies for Macadamias in NZ, Roger Warren (The Tree Cropper,June 1998)

Growing Macadamia Nuts, Henry Bell WNATCAQuandongVol 22, No 2

MacNut Farms, 914 South Head Rd, Helensville. From Internet www.macnut.co.nz

Round Nuts from Square One, Virginia Warren, Tree Cropper, Issue 12

Macadamia Varieties, Fay Seales, Tree Cropper, Issue 13

California Rare Fruit Growers, Fruit Facts from Internet www.crfg.org

California Rare Fruit Growers Yearbook, Volume 12, 1980, John Riley & Paul Thomson

Edible Tree Nuts in NZ, Bull, Jackson, Bedford

Macadamia: A Basic Understanding, Thompson H Cooper, Internet

Temperate & Subtropical Fruit Production, Macadamias, Michael Morley-Bunker

Fruit Growing in Warm Climates

Torere Macadamias Ltd for Henry Bell’s varieties

 

Compiled by: Gail Newcomb, January 2000. Variety update 2006.
Privacy removals and proprietory format conversion – December 2007.

 

Macadamia spp Table of Difference

	M. integrifolia	M. tetraphylla	Hybrid
Tree Height	21m	12m
Leaves at node	Three	Four (2-8)	Three – Five
Leaf length	20-27cm	50cm
Leaf margins	Entire with few spines	Serrated with many spines	More than integrifolia Less than tetrafolia
Leaf attach	Petiole	Sessile	Short petiole
New growth	Pale green, some bronze	Pink to dark red	Yellowish green, some green, bronze
Leaf shape	Obovate	Long narrow
Buds in leaf axil	3	2	2
Flower	White – cream Fragrant	Pink – purplish red, Very Fragrant	White –cream –pink- red, Fragrant
Raceme	10 – 20cm	18 – 39cm	15 – 30cm
Flowers open			October
Nut shape & Surface	Spherical: Smooth, thick	Ellipsoidal: Rough, Base thicker	Smooth or pebbled
Nut flavour	High oil, low sugar Roast	Low oil, high sugar	Best nutmeats
Nuts	Drop over 6 months to all year. Thicker stalk	Drop quickly and early in 6-12 weeks. Stalk like string	Some hold on tree
Hull	Thick, tough, shiny, stick to nut	Thin, tough, dull, many nuts fall free	Thin, tough, more shiny, fewer nuts fall free
Bark	Light greyish-brown, rough, spongy, leave scars barely visible	Light grey, smoother, dense, leaf scars visible
Wood	Moderately dense, brittle, easily broken	Dense, hard, strong, seldom breaks or splits	Same
Zone	Tropical 10 – 30°C	Subtropical 7 – 25°C
Optimum	20 – 30°C	12 – 26°C

 

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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