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Macadamia Culture & Varieties in New Zealand


NZ Macadamia Society Inc. 'Nut Grower Fact Sheet'    Macadamias in the Bay of Plenty

The article below is reproduced by permission of the New Zealand Macadamia Society.
NZ Macadamia Society Inc. 'Nut Grower Fact Sheet'

Macadamia Nut Grower Fact Sheet 2000

The New Zealand Macadamia Society Inc.
725 Harrisville Rd
R D 2, Pukekohe
The Macadamia nut is a native of Australia and is a member of the Proteaceae family and related to the NZ Rewarewa. Two species are grown commercially for food production, the macadamia tetraphylla and the macadamia integrifolia. New Zealand provides a special opportunity to grow a clean healthy quality product. Today, total world macadamia production accounts for less than 0.5% of the world trade in nuts. New Zealand produces less then 1% of this.

Macadamias require temperate climates and areas that have low frost risk though, as mature trees they will withstand minus 6 degrees - in general, if tamarillos can be grown so can Macadamias. Orchards are found in coastal areas of Northland, Auckland, Taranaki, Coromandel, Bay of Plenty, East Cape and Hawkes Bay. Macadamias flourish best in soil rich in organic matter, but can tolerate a wide range of soils from heavy clay to sandy loam. Main requirements include free draining, a good pH balance 5 - 6.5. Irrigation and shelter from severe winds is generally needed for young trees.

All macadamia trees grown for commercial purposes are grafted; there are approximately 600 different varieties not all of which are available in NZ. Macadamia integrifolia grows in the warmer climate of northern NSW and Queensland. Its production is sporadic in NZ, as it needs high temperatures and high light intensity. Macadamia tetraphylla comes from NSW and is more tolerant of the cooler climate. When choosing which varieties to plant you should consider the following:

It is advised to always plant a mixture of varieties scattered evenly throughout the orchard in order to ensure adequate pollination. The specific site will determine exact ratios and varieties. You may also choose to talk to your local nut processor. Some varieties crop better under certain conditions, and do well with the correct pollinators along side. Today in NZ most varieties are good croppers in their own right. The society can put you in touch with consultants and nurseries to help you with selection of suitable varieties.

Macadamias are best planted in the spring but can be planted at other times with extra care from drought, frost, etc. Trees are best planted, in rows, with a spacing of 7m apart and 5m minimum between trees, which allows for plenty of access, light penetration and access for insects to assist pollination. This allows for about 110 trees per acre or 280 per hectare. Allow headroom at the end of rows for machinery access and turning. A northerly aspect is preferred and the use of shelterbelts needs to be planned to protect young trees from prevailing winds, this is frequently removed as the trees come into production. Consider the availability of irrigation and drainage. Carefully consider the mixture of varieties you will plant and intersperse them well. Planting varieties which all exhibit the same variety characteristics eases the handling of the post harvest crop.

The macadamia is a forgiving tree and is suitable for those with limited spare time, but they respond well when cared for. The health benefits of habitually eating macadamias augurs well for their continued demand.

Seasonal pruning for shape and light is typically done in winter. Though the tree can be of substantial size, modern management maintains trees to a manageable height.

The Green Vegetable Bug Nezara viridula is the most serious threat, piercing the nut, staining the kernel and rendering it valueless. Regular mowing is recommended to keep the grass and weeds under control. Sheep are used in some mature orchards. Livestock is not recommended in the first four or five years and never goats. Rats can be a problem so effective eradication programs are essential. Possums may also eat soft green nuts. The Society is working to establish the best methods of controlling these pests, and the results of research will be published to members, as these become available.

Annual leaf and soil analysis, with appropriate response, assists in maintaining healthy trees.

Nuts are generally ready to harvest late May or early June, but can be later depending on the latitude picking can go on until late November. Nuts are picked by hand or mechanically depending on the variety of tree.

Top orchards in New Zealand have returned yields similar to the best overseas, i.e. 4-6 tonnes per hectare. In optimum conditions an 8 yr old tree can produce 8kgs nut in shell, increasing annually for a further 15 years, with the approximate price of $3 / kg in 1999. Many orchards not achieving above two tonnes per hectare are found to have basic problems. These problems include cool sites, shady places, poor cross-pollination, poor nutrition and crowded planting.

The object of husking and drying is to produce nuts that are crisp, light in colour and free from blemishes. Nuts should be husked as soon as possible after picking, within 24 hours is best. The Society may be able to help you find someone to work in with nearby. Moisture must be reduced to 1.5% for processing this can be assisted by hanging in onion sacks for 8 - 12 weeks depending on the ambient temperature and humidity. The dryer the nut the better the storage characteristics and eventually the better the payout received. The nut should be firm and crisp. A kernel that is soft and doughy when bitten indicates that further drying is necessary.

Most orchards sell their crop as nut in shell (NIS) to processing companies. Contact the society for a list of these.

Packaging to reduce exposure to light, moisture and oxygen enhances the final taste of the nuts, and increases the shelf life. The society has developed criteria to ensure the highest standards are maintained.

The New Zealand Macadamia Society Incorporated is developing a number of exciting new marketing initiatives designed to increase the awareness and demand of New Zealand macadamia nuts. Interestingly, in 1999, New Zealand was still importing a large percentage of its macadamias from Australia.

For more detail information send $5 and S.A.E.
        The Secretary,
        N Z Macadamia Society Inc.,
        997 Beach Rd,
        Auckland 10.

Information on current initiatives can be obtained by contacting the society.

This document is free to be copied and distributed. The intent of this document is to provide a brief overview of the issues involved in planting a macadamia orchard. It is not intended as an authoritative publication and no responsibility is taken for the reliability of any of the information contained in it. It is recommended expert advice be sought, or more detailed information obtained from the growers guide (Send $5 and SAE to The NZ Macadamia Society Inc.) before any investment is made.
 Note: although they don't include the copyright notice. this work is '© Copyright The NZ Macadamia Society Inc', regardless that it is permitted to freely distribute it.

Reproduced with permission of the NZTCA

Macadamias in the Bay of Plenty

Nick Nelson-Parker*
Macadamias are considered by most to be a golden crop- you pay gold to buy them to eat. However, the reality in New Zealand is that most orchards are cropping so poorly that the owner is making copper rather than gold. Therefore, when our branch had a field day to a macadamia orchard that was realizing its potential, I felt the information shared required a wider audience.
In September 1988, Beverly and Robin purchased this 2.5 ha property at Whanarau Bay, on the western tip of East Cape. About three gates down the road is a newly-planted banana orchard, and every flat paddock for the previous haalf hours driving is clothed in the most luxurious squash plants. It is obviously a warm spot, and the soil looks fertile. Inside the orchard, it is clear that the owners are in full control. The grass, the hedges and the macadamia trees are immaculate.
In 1989 their frist crop was 1.5 tonnes off 370 trees aged five to seven. Even though this is quite good for New Zealand, Beverley turned her attention to improving this yeild. By winter 1993, after a fairly poor pollinaton, they had increased the crop to 4.2 tonnes off the 370 trees. That is 12 kg per tree. Many other commercial orchards in this country are only getting 2 kg or less per tree. Some are getting 8 kg per tree in some years. The yeild from mature macadamiaas in Hawaii is over 16 kgs per tree, and can be as high as 68 kgs from a 10 year old tree. Beverly expects to pick 6 tonnes in 1994. How did they get this lift, and how do they plan to push yeilds even higher?
Observing and Recording
They embarked on a programme of recording the crop off each tree, and recording what the neighbouring varieties were. Beverly found that the main varety, Beaumont, was giving good yeilds, but that pollination  was important. In addition, one tree of PA39 gave extremely good crops. She observed that biennial bearing was occuring. And she noticed that sometimes, although there were plenty of flowers, only a few nuts would set on each stalk. This occured even when the crop was next to the best pollinator. She also noticed deficiency symptoms showing up in the leaves as the crop started to fill out in the trees, even though they put a commercial fertilizer dressing on the orchard each year.
They decided to monitor the nutrient levels by having regular foliar analyses done. Beverley had read that research in Australia linked high boron levels with a good nut set, so they included a check on their boron levels. These tests confirmed what Beverly's eyes were telling her: that nutrient levels were not adequate all the time, and that boron levels could be higher. Beverly and Robin decided to increase the basic fertilizer levels and correct these deficiencies. They also increased nitrogen levels, despite the prevailing Australian and New Zealand belief that high levels of nitrogen prevent macadamias from cropping. In 1993 they applied four sprays of zinc and boron starting in January, applied 900 kgs of Nitrophoska blue in August, and then did another foliar analysis in November to assess the situation.
Because the nut set had been so good, probably as a result of the boron spray, the trees were already short of nutrient! A 250 kg dressing of Calcium Ammonium Nitrate together with 300 kg of Causmag was applied to see the trees through developing the nuts. Iron was also added to the foliar sprays to correct spring deficiencies of that element. Sulphur deficiency is still a concern, and that is the next nutrient that Beverley wants to examine.
Another aspect contributing to their success is orchard hygiene. When they initially purchased the orchard, their first crop had to be dumped because of bug damage. Well-mown grass, with strips sprayed between the trees, helps to reduce green shield bug. In addition, they spray with AttackTM four times at 7 day intervals, starting in February. They have reduced the damage on their crop from 30% to 1% by this programme. It is important not to overspray the orchard and kill the leaf roller moth, because that is considered an important pollinator for macadamias.
Oppossums have not been a problem, but rats are a worry. When there are macadamias to eat, they will not touch any other baits. In the autumn Beverly and Robin go around the orchard with long poles to remove all the old birds nests. Otherwise the rats would fill these with nuts and never need to come to the ground.
Another aspect of orchard hygiene is tree pruning. All the skirts on the trees are trimmed off to facilitate weed spraying and mowing. Internally, the trees are being thinned out to allow better access for bees for pollination and also people for picking. The less dense trees appear to be cropping better too. Attention to detail here is making the difference between an average orchard and one that is a top performer. Beverly is very particular about how to prune her trees. This is especially important wth the current New Zealand varieties that have to have their nuts picked. The trees should be a central leader with branches spiralling around the centre at 70 cm spacings. This makes the tree much less prone to breakage. Shelter is important for macadamias because the cooling effect of the wind retards their growth. Strong winds also cause their branches to break. If Beverly and Robin were planting a new orchard, they would first plant shelter, but not as much as the original orchard. They would not plant eucalypts because they are greedy trees and they get too big.
Macadamia Varieties
Beverly and Robin's orchard presents an unique opportunity to compare varieities. They have 23 different varieities already bearing, adjacent to each other and to different pollinators. In addition they have recently planted a number of new varieties as a trial. This is a summary of  Beverley's current information on varieties, but their nutrition programme could lift these yeilds markedly.
This is an Australian variety. It has good taste, a high oil content, and a crackout of 39%. However, the nut does not drop when ripe, giving high picking costs. Drying is also a problem, as the kernel sticks to the shell on one side if it is not turned regularly in the early stages of drying. The customer sees this as a basal stain on the kernel. A large percentage of the kernel tends to fall in half. In 1993 a block of 8 year old Beaumonts, with no pollinators except around the outside, gave 18 kgs. But 10 year old Beaumonts next to Nelmac 1 gave 22 kgs, while 10 year old Beaumonts next to Nelmac II averaged 28 kg per tree.
One 7 year old tree of this variety gave 33 kgs. Unfortunately they have only a handful of PA39, and can only assume that other trees of the same variety would do as well. The kernel is clean and attractive. In this orchard they gave 95% grade 1 kernel, with a crack out of 40%. Another great virtue is that the nuts drop when ripe. It pollinates Beaumont, though no figures are available to compare it as a pollinator to Nelmac II. It is a small compact tree, very prickly, and very susceptible to green shield bug.
PA39 is one of Brian Piper's selections. However, none of the other Brian Piper selections have performed well in this orchard.
Nelmac I
A South African cultivar. Although the nut is slightly elliptical. which makes cracking awkward, and has a low crack out because of the thick shell, processors like this variety because of the high quality kernel. It has a bland taste like the Hawaiian nuts, and a high oil content.
It is quite a light cropper, with a10 year old trees yielding an average of 8 kg, It is a month late in flowering, which may be hindering its pollination effect on Beaumont and its own cropping. However, if the pollination could be corrected, it would be a very good variety because the nuts drop when ripe.
Nelmac II
Another South African cultivar. It has a sweet nut, which means that it has to be cooked carefully so that the sugars do not caramelise. The sweet nut does not taste good when processed, but people who eat it uncooked relish the taste. The nut is too big for processors, and has an open micropyle (hole in the shell) which lets in mould. The crack out percentage is high. Ten year old trees average 22 kgs per tree.
It is a popular variety because of its pollination of Beaumont, and the yields are almost comparable. It appears to be susceptible to iron chlorosis, with bleached leaves showing up in early summer when the tree is under stress.
A Gordon Titirangi selection. It was released as a pollinator for Beaumont, but it is probably better pollinated by Beaumont. The nut is small and of good quality, with a high oil content. The kernel is clean and attractive, and the crack out is high.
Another Gordon Titirangi selection. This nut has a thin shell, so rat depredation and shield bug damage are both real problems. Nine year old trees gave 8 kg per tree.
Another Gordon Titirangi selection, selected as a pollinator for Beaumont. It has a good quality nut.
Another Gordon Titirangi selection. Beverly has only just planted this variety. It had 100% grade 1 nuts at Woodhill. [Auckland]
Own Choice
A Hawaiian variety. This produces the best quality nut they have to work with in their little processing set-up. The crack out is 32%. Nine year old trees produced 22 kgs each, though the nuts do not drop when they are ripe. It is a good pollinator for Beaumont, and appears to be largely self fertile on their orchard.
Is a pure M. tetraphylla from Australia. It is a good pollinator for Beaumont. Seven year old trees produced 7-5 kgs.
Nutty Glen
An Australian hybrid selection. The nut is large and of good quality. It is popular in Australia as a rootstock.
Is another of those varieties not planted much, but often used in breeding new varieties. Its good characteristics include the yield (17 kgs off 9 year old trees), the fact that it drops when ripe, and a kernel of quite good quality. On the other hand, the nut is elliptical, so is difficult to handle for processing. The crack out is only 33%.
If they were doing it all again
Beverly is uncertain what varieties she would want to put her money on a second time around. Ideally she would like to do away with all the Beaumont and just have varieties that drop when ripe. In spite of that problem, there is presently no other proven variety with comparable yields. Therefore, the orchard would have a quarter Beaumont, planted in double rows. To get good pollination, every tree in the orchard would be next to a different variety on at least one side.
The pollinators would also be in double rows. These would possibly be GT1, with as many PA39 as they could obtain. A certain number of GT207 would also be included on a trial basis. Other considerations would be Nelmac II, because of its good pollination of Beaumont, or Nelmac I, if the cure for its poor pollination could be found.
Their spacing would be 6 x 6 metres as currently favoured in Australia. There, they are finding that when they thin out the trees, the crop only drops for one year before the remaining trees make up the difference. The current Davy/Moyle orchard is planted at 4 x 5 metres.
Nagao, M A & Hirae, H H. 1992. 'Macadamia: Cultivation and Physiology'
Critical Reviews in PLant Sciences 10 (5): 441-470

 Richardson, A C & Dawson, T E. 1993. 'The Nutrition of Macadamia Trees in New Zealand'
The Orchardist of New Zealand 66 (9): 37-40 (October 1993)

 Reproduced by permission of the New Zealand Tree Crops Association from 'The Tree Cropper', the Official Journal of the New Zealand Tree Crops Association, Issue number 6, December 1995.
(This article prints out at about 8 printer pages)
 Note: this work is '© Copyright Nick Nelson-Parker and The NZ Tree Crops Association Inc', regardless that it is permitted to freely distribute it.

MacNuts in Helensville, North Auckland, publish this good growers guide. Covers: Location, Varieties, Planting,  Pruning,  Weed & Pest Control, Fertiliser,Yields, When to Harvest, Husking, Drying & Storage
Macadamia Varieties in the New Zealand home garden - a Naturalhub article on home garden cultivars.
http://www.naturalhub.com/grow_nut_cultivars_macadamia_New_Zealand_home garden.htm

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