Over the three or so years that I have been immersed in the macadamia industry, there’s a name that kept popping up; so much so that I started to attach a legendary status to it. He’s literally been around since day dot of macs in South Africa. He’s served as the CEO of a mac processing company, been SAMAC chairman, advised growers in a technical capacity for another processor and he now consults – mostly to growers further north in Africa.
So, why on earth would a consultant, especially one of this calibre, be willing to talk to TropicalBytes? We all know that this platform is about sharing and learning but he makes his LIVING that way … I was finally spurred on by a TropicalBytes follower (thanks for the shove Simphiwe) who convinced me that it was worth the possible rejection as this man has seen over 3 million macadamia trees on more than 1000 properties on four continents. So, I made the call.
Philip Lee was kind and engaging from the onset, “Sure,” he said, “we can chat.” So, I beetled off to ‘maritzburg, we sat on the lawn, and here’s what he said …
I’m lying! He actually shared his Mac101 course with us, with permission to publish. This is the official SAMAC document on farming macs so it might not be new to you but we found countless gems worth revisiting … I’ve summarised it, removed some of the more technical stuff and added pictures but Philip’s knowledge is intact. The full manuscript, with countless numbers, figures and graphs, is on SAMAC’s website (accessible to members).
Even this summarised version is incredibly comprehensive so this will be a two-part story, covering the following topics in each one:
In this edition:
- Ideal climates
- Industry Overview
- Land prep and Orchard establishment
In the next edition:
- Orchard Floor Management
- Pests & Diseases
With that said, let’s look at how the origins of macs should be considered when farming them …
Macs are indigenous to the coastal areas of eastern Australia, where the mean monthly temps in winter are a min of 8°C and a max of 23°C and in summer they are 18°C and 28°C.
There are 3 keys when it comes to temperatures:
- A lack of extremes (macs grow very little when it’s below 12C and, above 35C, photosynthesis virtually comes to a standstill)
- A required number of heat units, at the right time.
- For Growth. 600 to 1000 units required while fruit is growing (Oct to Dec i.e.: 3 months).
- For Oil Content. 1000 to 1350 units for oil accumulation (Jan to March i.e.: 3 months).
How to calculate heat units: Take the mean daily temperature [ (max + min) ÷ 2 ] minus 12°C (the base temperature for macs). Add all those together. See below for an example of the calculation.
- A minimum of 120 hours (on contiguous days) where the minimum temperature is less than about 18°C, in order to initiate flowering.
- High winds will damage the brittle branches.
- Frost will cause loss in young trees and crop loss in older trees if experienced over flowering to nut shell hardening stages.
- Hail will bruise kernels, sometimes even through a hardened shell, and damage stems and branches creating susceptible points for fungal infections.
- Altitudes – Macs can be grown in higher altitudes, as proven on a few 1800m high farms in Malawi but the shells are generally thicker the higher you go resulting in lower kernel recoveries (TKR).
- Rainfall – in the coastal areas of Australia, where macs originate, annual rainfall is about 1200mm.
Even in the regions where macs are indigenous, there are droughts and cyclones so it is not so much a matter of only planting macs where the climate is perfect and best emulates the original forests but rather to identify the risks of the area you are farming in and formulating plans to best manage those risks.
Philip states that, in terms of climatic requirements, the coastal strip of approximately 50km inland from the sea stretching from Port Edward in the south to Richards Bay in the north, is probably the best place on earth in which to grow macadamia nuts. Both the yield and total kernel recovery rates coming out of this region are world-class, probably due to the moderating effect of the sea on temperatures and the year-round higher humidity levels.
Philip provides some fascinating statistics around the history of, and outlook for, the South African industry – here are a few highlights:
- First seeds brought into the country in 1935, planted at Reim’s Nursery in Hillcrest, KwaZulu-Natal.
- First commercial orchards planted in the late ‘60s.
- Mid ‘90s saw significant plantings, driven mostly by Mpumalanga farmers diversifying away from citrus, tobacco and other crops that had become less profitable.
- Up until 1998, when Mpumalanga took over, Limpopo had the highest number of trees. In 2015, KZN also overtook Limpopo and is now second only to Mpumalanga.
- Cultivar mix in South Africa is heavily weighted to Beaumonts; 50% of all trees planted in the last 10 years are of this cultivar. Next most popular is A4 (20%) and then it’s 816 (10%). I’d like to pause on a very interesting point that Philip raised here; “Only three cultivars comprise 80% of the trees planted in SA since 2013. Whether or not this heavy reliance on one cultivar, 695, will come to bite the SA industry in the future remains to be seen. It certainly flies in the face of the wisdom which recommends that macadamia growers should diversify their plantings to include at least 4 cultivars on each farm (about 25% of total area planted to each cultivar), so as not to have all our eggs in one basket and to benefit from the positive effect of cross pollination between cultivars, which improves both fruit set and fruit size, thereby contributing to both yield and quality (larger nuts have higher kernel recoveries).”
- A moment to celebrate and take a bow: Back in 1996, macs were a relatively insignificant player in the South African horticulture landscape, with only 1 million trees and production of 840 tons kernel with wholesale value of R32 million. 26 years later, our magnificent macadamia industry has certainly risen to prominence, not only as a leader in the South African subtropical crop and horticulture sectors, but also as the leading supplier of quality macadamia nut products globally. With 18 million trees, of which only about 42% (7.6 million trees) were in production (6 years and older) in 2021 and production of 53 320 tons DIS in 2021 worth about R4 billion, the achievements of all role players who have contributed to this incredible success story are indeed worthy of praise.
- Answer to the million-dollar question; I am always asked about how the increased supply will affect price and here is Philip’s response: “SA production increased from 24 000 tons DIS in 2008 to 59 050 tons DIS in 2019 (2.5 – fold increase in 11 years), while the global price of kernel went from $8/kg to $18.80/kg (2.4 – fold increase over the same period). So, an increase in South African (and global) macadamia production has not resulted in any decline in global price of the product. Indeed, the global macadamia nut price increased by two and a half times in 11 years despite the same order of increase in South African (and global) production over the same period. Few people seem to understand that the macadamia nut is “price inelastic”, a term in economics used to define products for which there is no inverse relationship between production volume and price.”
- Despite SA currently being the world’s largest producer, Philip suggests that this title will not be held after 2026 when Chinese production will overtake ours. And how does this affect the future for the SA mac industry? Philip says, “the South African macadamia industry needs to focus on the development and maintenance of markets for top quality macadamia kernel products going forward.” He justifies this statement because the Chinese NIS demand will be fed by their own produce and their exports will probably only suit a lower quality market, leaving the high end, kernel market the one to aim for.
- Philip’s Mac101 course if full of numbers and graphs and this one really stood out – the Downward Trend alert … Philip explains; “Figure 2.19 clearly shows a disturbing downward trend in average yields per hectare in SA, Australia, Hawaii and Malawi in the last 5 to 7 years. In Hawaii and Australia the 2021 yields are the lowest since 2002 and for South Africa the lowest since 2007. There must be a host of reasons for these downward trends – something for grower organisations to seriously ponder. Can we identify the main causes of this disturbing trend? Is it purely driven by climate change or are there other factors that farmers may be able to control? If so, can we put in place appropriate farming practices to remedy the decline?” Important questions, for sure!
- A final warning: price adjustment loading … Philip is careful to emphasise that this is not
- A: a price crash like previously experienced, none-the-less, it is a downward price shift, largely due to global economic catastrophes like Covid and War or
- B: a price adjustment in a response to oversupply. But, it is going to require some fancy footwork … Philip suggests the following would be in our best interests:
- A global, collaborated focus (preferably based in Australia who have the largest gene-pool) on plant breeding with the goal of developing cultivars with increased yield off smaller canopies.
- A shift in the way we establish (more high density) and manage (more intensive) macadamia orchards.
The more we understand mac tree phenology (the study of cyclic and seasonal natural phenomena) the more we’ll be able to refine our management inputs to achieve the optimum outcomes. So, rather than following the calendar, we should follow the tree and maximise our outputs through well-timed inputs. This can be done in various ways …
Vegetative Growth, using Nitrogen
Nitrogen stimulates vegetative growth. The natural vegetative flush pattern is a minor peak in spring and a major peak in summer, and there is good reason to try to reverse this situation in commercial production – we can do this with nitrogen. The logic being that if we stimulate vegetative growth as much as possible in the spring flush, we can minimise the depletion of carbohydrate reserves, shown to occur in August/September. While the carbohydrate reserves will again build up during the main summer flush from November to January, the aim is to start this build-up from as high a base as possible, so that the tree enters the high energy demand phase of nut maturation and oil accumulation in the kernel with as much stored energy as possible, not only to complete the oil accumulation process from January to March / April, but also to fuel the following spring vegetative flush.
So nitrogen is used to stimulate the spring and summer vegetative flushes and then reduced to a small amount in January and then stopped, so as to reduce the late summer/autumn vegetative flush. Here the reasoning is that the tree needs all of the energy to be channelled to the kernel for the conversion of sugars to oil, with as little energy as possible being diverted into new vegetative growth. The goal is to produce as many nuts as possible that have the required oil content of 72% to be classified as premium grade kernel and to ensure that “immature” kernel, those with less than 72% oil, is minimised.
Root Growth, using Phosphorous
Philip explains that root growth flushes follow a similar pattern of distribution over the season as vegetative growth flushes, with the peaks of root growth activity in spring (August / September) and late summer (mid-January to mid-April). It would therefore be appropriate to apply the phosphate fertiliser required to stimulate root growth in July / August and December / January, so that it is available for these root growth flushes.
Philip further advises that mac trees need well-aerated soils, rich in carbon, which can be boosted by appropriate soil preparation at planting stage and adequate supplementation of mulch and organic matter throughout their lives.
Nut growth, using pruning and manipulation
Unlike most of the world where it is common that both maturing fruits and new flowers are on the mac trees at the same time, making both pest control and canopy management interventions something of a nightmare, in South Africa, and more specifically in KwaZulu-Natal (one of the main reasons it is the best place in the world for macadamias), a fairly concentrated flowering takes place in most seasons.
Most flowers are produced on wood that is two years old which is growing more horizontally than vertically, and from fruiting spurs. Knowing this, we can manipulate and work the trees into maximum yield mode to ensure early production of nuts in the life of the trees.
Philip advises that the choice of which cultivar to plant can only be made on the basis of sound yield and quality data for the specific area, or from an area with similar climatic conditions.
Yield is assessed in terms of these measurables:
Quantity of kernel recovered, measured in Sound Kernel Recovered (SKR) and linked to these characteristics:
- Precocity. This is the ability of a cultivar to start bearing at an early age. The leaders in this race are generally 695 (Beaumont), 791 (Fuji), 814, A38, A4, A16 and Nelmak 2.
- Concentrated nut drop period. How long is this time frame and will that work for your operation? Some cultivars have extended out of season flowering, e.g. 791 (Fuji), which leads to an extended harvesting period. Some cultivars have a single pronounced early flowering (May / June) followed by a main flowering (August / September), e.g. 344 (Kau), which also extends the harvest period. 695 (Beaumont) does not drop its nuts naturally and they have to be physically removed from the trees. While this is a labour-intensive operation, it allows for a once-off harvest of this cultivar.
Yet other cultivars retain a proportion of their nuts on the trees owing to the so-called “stick-tight” phenomenon. These cultivars require a final stripping harvest round near the end of the season, which also adds to harvesting costs, e.g. 816, which can present 15-20% “stick-tights” at the end of the harvest period.
- Tendency for alternate bearing. Some cultivars have a tendency to produce high yields one year followed by low yields the following year, especially at maturity (15 years old +). This is a phenomenon common to many subtropical tree crops and has been displayed in both commercial macadamia orchards and in cultivar trials. Alternate bearing patterns are also quite strongly influenced by climatic conditions and were observed in many orchards during the last dry periods 1992 to 1995, 2003 to 2008 and most recently in the seasons since 2015. As illustrated by the yields from the unirrigated cultivar trial at Kearsney, near Stanger in KZN, alternate bearing is a feature of dryland orchards.
Quality of kernel recovered, measured in Grades and linked to these characteristics:
- Total Kernel Recovery – the total amount of kernel recovered expressed as a percentage of the total DIS weight. This is further divided into two components, namely Sound and Unsound Kernel Recovery. Kernel recovery rates for a given cultivar can vary from region to region and season to season, owing to climatic differences. Unsound Kernel Recovery rates will also vary and are most influenced by the level of pest and disease damage, physiological disorders and inappropriate post-harvest handling methods.
- Whole kernel size and shape – some cultivars, notably the hybrid cultivars, have large whole kernels (e.g. Nelmak 2 and 26, A4 and A16) which generally weigh 3-4g each. Some cultivars produce kernel of variable size in some seasons (e.g. Nelmak 2). Some cultivars, again most notably the hybrid cultivars, produce kernel which is more oval (flat – round) in shape than round, predisposing them to lower whole kernel recoveries using existing cracking machinery (e.g. Nelmak 1, 2 and 26).
- Roasting and eating quality – probably the most important quality attributes of a cultivar. This is related to sugar and oil content and is often not given enough attention in cultivar assessments. Some markets prefer whiter kernel which is difficult to deliver when sugar content is high as the sugar caramelises in roasting. Although the sweet-toothed among us LOVE sweet nuts, they aren’t for everyone.
- Inherent kernel defects – in addition to differences in size and shape, some cultivars produce kernel which exhibit spots or minor blemishes under certain conditions. An example is 791 (Fuji) “spot” which occurs on some batches of kernel of this cultivar, the cause of which is presently unknown.
Most common cultivars for SA climates:
- Hybrid cultivar arising from naturally occurring crosses between Macadamia integrifolia and Macadamia tetraphylla
- Drought tolerant.
- Naturally produces wide crotch angled branches therefore easy to train.
- While it was indeed very effective as a clonal rootstock because of the relative ease in propagating it by rooting cuttings, it was the very good yield performance in the SAMAC cultivar trials established in Tzaneen, Burgershall and Levubu in 1993 that led to the planting of over 6 million “695” trees around South Africa since the year 2000.
- Mature nuts do not drop naturally from the tree so require hand harvesting from the tree or spraying with ethapon to induce abscission.
- Achieves 30 to 35% SKR.
- Generally only 50% snack grade kernel (whole kernel styles).
- Kernel from hybrid cultivars generally require different roasting times and temperatures to the general mix of integ cultivars, which make up the bulk of the internationally traded macadamia nut product. South African research into the roasting requirements of a range of cultivars in the late 1990’s (Lemmer & Kruger, 1999) showed the roasting parameters of “695” were the same as those of the existing integ cultivars, whereas roasting parameters of the hybrid cultivars “N2”, “A4” and “A16” were different.
- An open growth habit cultivar.
- Appears to perform best at low altitude on the KZN south coast, where it remains a popular choice in new plantings.
- Produces disappointing yields in hotter areas (Table 4.2 shows “788” producing the lowest yield at Empangeni) like Levubu and even Tzaneen and many parts of the Mpumalanga lowveld, where it is not popular, both because of poor yield performance and difficulty in dehusking because of the very thick and dense husk.
- It has good kernel quality, 30% plus TKR,
- Fairly low whole kernel percentage of 30 to 60%.
Table 4.2: KwaZulu-Natal North Coast yield and value data 2014 (8 year old trees – irrigated)
|Cultivar||DIS (kg/ha)||SKR %||SK (kg/ha)||Value R/ha||R/kg DIS|
- Very precocious, sometimes seen flowering in the nursery!
- Relatively open growth habit but tends to make long vertical stems and also lateral branches so requires a lot of heading back from a young age to optimise bearing wood low down in the tree and capitalise on the natural precocity.
- Although it does produce more discolouration (browning) along the sides of the kernel ridge (a condition commonly referred to as “791 spot”) than any other cultivar, it makes up for this malady by producing very high yields at a young age. Many growers have achieved yields in excess of 6 tons DIS/ha from year 8 onwards especially at high density (500 to 800 trees/ha).
- Achieves about 30% TKR.
- 40 to 50% snack grade kernel (wholes).
- Very precocious and possibly even more precocious than either “695” or “791”, as it was the highest yielding cultivar in the SAMAC cultivar trials planted in Tzaneen in 1993, as illustrated in Table 4.1 and Figure 4.1. Philip says he’ll never understand why this information has never been landed in the South African mac industry.
- It has a spreading growth habit, producing lateral branches with wide crotch angles, so fairly easy to train to maximise bearing wood low down in the tree.
- It was never released as a recommended cultivar in Hawaii (so never given a name), because it produces small nuts, with average kernel mass of 1.8 to 2 grams, so did not meet the Hawaii standard of 2 to 3 grams average whole kernel mass.
- Despite this, it yields fairly high TKR of 35 to 40% depending on conditions.
- Higher percentages of whole kernel at cracking than either “695” or “791”, in the region of 60 to 70%, of which a high proportion are classified in the Style 1S (small whole kernel) grade popular in the Japanese market at premium prices and used primarily for chocolate coating.
Table 4.1 Merensky cultivar trial in Tzaneen (planted December 1993)
Tree spacing 8 x 4m (312 trees / ha)
|WIS / tree (kg)||TKR%||Total SK (kg/ha)||Accum Total Value (R/ha)|
WIS (kg/tree) X 0.85 = DIS (kg/tree) (Assumes mass loss from WIS to DIS is 15%)
DIS (kg/tree) X 312 = DIS (kg/ha) (yield per tree at 312 trees/ha to yield per hectare)
DIS (kg/ha) X (TKR% – 2) = SK (kg/ha) (Assumes 2% unsound kernel loss from TK to SK)
SK (kg/ha) X 120 = Accum. total value (R/ha) (Assumes farm gate price R120/kg kernel)
The accumulated total values in Table 4.1 are made the more incredible if one uses the present farm gate value of kernel of about R204/kg, rather than the (2011 to 2015) five year average price of R120/kg as used in the example. At R204/kg kernel, the difference in total farm gate income over the first 7 production years between the best and worst yielding cultivars in the Merensky trial would be a staggering R1,89 million/ha. No better way to emphasize the importance of selecting the right cultivar to plant on your farm, and, of course, implementing best management practices to achieve the kind of yields produced in the Merensky cultivar trial.
- A very upright growing cultivar requiring much tree training to widen the naturally occurring narrow crotch angle branches produced. Absence of tree training from a young age results in the first fruits being produced higher than two metres from the ground, when the vertical branches will bend to a more horizontal orientation and only then begin to produce secondary and tertiary branches. Because of this, trees not trained from a young age will take 4 to 5 years to produce their first crop and 8 years plus to reach the target yield of one ton kernel per hectare.
- Produces the best quality nut, with perfectly round, creamy white whole kernel, resulting in extremely high TKR upwards of 40%.
- Highest percentage of whole kernel, at cracking, of all the available cultivars. Batches of “816” from KwaZulu-Natal growers consistently achieve around 80% of whole kernel styles. One grower who has both “695” and “816” trees has commented that he receives the same payment from the factory from 60kg NIS of “816” as he does from 100kg NIS of “695”. So what it lacks in terms of precocity and NIS yield, it makes up for in terms of quality.
“842” and “849”
- Two cultivars with similar open growth habits and relatively early bearing potential. Somewhat difficult to identify in the orchard because of their similarity, there is little data available for these two cultivars only planted in significant numbers in the last 10 years.
- Both have been found to produce high yields in hotter areas such as Levubu and Empangeni.
- TKR levels upwards of 35% in both localities.
- Abbreviated to “N2” this is one of the hybrid cultivars from naturally occurring crosses between integrifolia and M. tetraphyllas.
- It has a spreading growth habit so requires little training to achieve a productive canopy.
- Although fairly precocious, it has a tendency for alternate bearing and showed the most dramatic yield decline in the Merensky cultivar trial after year 9, as a result of the combination of inadequate canopy management and the drought.
- Philip doesn’t like this cultivar because of how differently it behaves in roasting. This view is based on an actual study he was involved in. Nelmak 2’s high sugar content means they come out darker in roasting and, to avoid this, need to be roasted at different temperatures. This makes them less attractive for processors so he would prefer to rather opt for similar performers that don’t challenge the processors as much.
“A4” and “A16”
- Two Australian hybrid cultivars arising from artificial (hand pollination) crosses of integrifolia and M. tetraphylla selections.
- Both produce good yields of very large nuts with thin shells and hence very high kernel recoveries.
- Quite similar to cultivar “N2” in appearance, with spiny leaves, the canopy of “A4” is fairly open while that of “A16” is more confused with many lateral branches twisting and turning in a manner resembling the vining growth characteristic of copper deficiency.
While I was chatting to Philip, I asked what his personal preferences were, in terms of cultivars and he mentioned one that I fell in love with on my trip to the Cape last year – A38. This cultivar was a part of a study conducted at Kearsney which proved that it certainly is one worth considering …
The best yields from another SAMAC cultivar trial planted at Kearsney near Stanger with ten cultivars in April 1998 and an additional five cultivars planted in April 2000, are compared with the best three cultivars in the Merensky trial – Figure 4.3. This also shows the difference in yield profile of irrigated trees in the Merensky trial with the dryland trees in the Kearsney trial.
The best yields up to age 18 in the Kearsney trial were produced from cultivar A38 followed by cultivar 814 then 791, 344 and 695. Clearly the benefit of irrigation is to generate higher yields earlier in the life of the orchard, resulting in greater profitability. Both cultivars 814 and 695 had generated accumulated yield over 100 kg WIS/tree by tree age 11 under irrigation at Merensky, whereas the best yielding cultivars A38 and 814 under dryland conditions at Kearsney achieved this level of yield at tree age 14.
Accumulated yields for all the cultivars in the Kearsney trial converted into kg DIS per hectare are shown in Table 4.3. Once again, the importance of selecting the appropriate cultivars for a specific location is emphasized by this data, the difference in value over the first 21 years of orchard life is R1.39 million between highest producing cultivar 344 and lowest producing cultivar A4. Up to age 19 the value difference is R1.63 million between highest producer A38 and lowest producer 842 in the part of the trial planted two years later (values calculated using average farm gate price of R55/kg DIS, approximately the last ten years average price).
|Table 4.3 Kearsney cultivar trial|
|Accumulated yield to age 21|
|Cultivar||DIS (kg/ha)||Value @ R55/kg DIS|
|Accumulated yield to age 16|
Philip points out that the Kearsney trial was a co-operative trial which, although planted by SAMAC personnel, was managed by the private grower on whose farm it was planted. The Kearsney trial did not receive the same degree of micro-management and control as was exercised at the Merensky trial over the years. Hence the accuracy of the yields from the Kearsney trial may not be exactly comparable with those at the Merensky trial. Nevertheless, the Kearsney trial has generated some useful information regarding yield performance of cultivars under dryland conditions for that region of KZN. Most notably the good performance of the old stalwart cultivar 344, the relatively poor performance of cultivar A4, and the very good yield produced by cultivar A38.
It is also interesting to note that the top yielders under irrigation in Limpopo, cultivars 814, 695 and 791 are also among the top performers in dryland conditions in coastal KZN. For Philip, it remains something of a concern that these most useful results from the Kearsney trial, now 20 years old, have hardly ever been published or made known to SAMAC members, especially new growers, to assist them in deciding which cultivars they should plant.
Philip advises that, once you’ve decided what to plant, it is wise to plant at least 4 cultivars in relatively equal proportions. Firstly, so as not to be reliant on a single cultivar should the market at any stage discriminate against that particular cultivar. Secondly, because of the well documented benefits of cross pollination, it is wise to plant 2 cultivars in alternating single or double rows within each block, so that each tree of each cultivar is adjacent to a tree of a different cultivar. It is known that the cross-pollination benefit decreases by 25% for each row moving away from the pollinator cultivar row, so the fourth row of trees from a pollinator row derives little or no benefit from cross pollination. The benefits of cross pollination include better fruit set and better fruit size, so the impact is on both yield and TKR% (larger nuts have higher kernel recovery as kernel mass is larger in proportion to total NIS mass).
And then I pressed Philip to declare what he would plant if somehow gifted with a piece of land suitable for macs today … his answer was:
- 25% Beaumont
- 25% A4
- 25% 816
- And then, for the last 25%, he would hold on for one of the new cultivars coming out of Australia. One he particularly likes is MCT1. It has a 40%+ kernel recovery and is producing 1 to 2kgs per tree at 3 years old. It looks like a 788 but has dwarfing characteristics. The rights are owned by Sapekoe who are being a little slow in sharing it. Released in 2018.
- And he again mentioned A38, which he would chose long before Nelmak 2. Yes, this means that he’d need to plant less of the others … maybe 20% of each.
Less than 3-year-old MCT1 cultivar
LAND PREP AND ORCHARD ESTABLISHMENT
Philip has done extensive work on budgets and cashflows for macadamia farms. This is an incredibly customised exercise as each farm is so different. Philip is available to anyone needing his services in this regard, and of course, all other mac-related issues.
Once a farmer has made peace with the high cost of establishment and relatively long-term returns, Philip goes on to advise on the physical mac farm establishment:
- Soil testing. The results of which will reveal what the soil needs in terms of corrective additives like lime, gypsum and phosphates.
- Land prep (bush clearing and deep ripping) is best done mechanically; preferably across the entire field but, at minimum, the row area where the trees will be planted. There is only one chance to address the following essentials properly and that is before the trees go in.
- effectively incorporate lime to correct soil acidity through the depth of the soil profile,
- incorporate phosphates if required through the depth of the soil profile,
- aerate the entire rooting depth of the trees (down to 1m) – particularly important for red clay/Hutton soils.
- Ridging. Philip warns that this should only be done if necessary i.e.: if there is an issue with soil depth or drainage because it is both costly and could result in moisture problems as these ridges will dry out faster than flat land.
- Spacing. Philip explains, “There is no single perfect spacing, it is dependent on the objectives and management style of the individual farmer. It will be driven by the slope of the land and the need for tractor and implement access. Steeper slopes require wider spacing, while higher densities can be used on flatter land. Ideal tree populations are 300 to 600 trees per hectare.
- Extensive Farming: Growers with large land areas might want to simplify their management system and therefore choose extensive management options with wide spacing, little or no tree training or pruning, in some cases no irrigation, resulting in low yield per hectare but accompanied by low cost per hectare.
- Intensive Farming: Growers in areas where land values are high and the area available for planting small, might choose intensive management systems with high plant population under full irrigation and canopy management aimed at optimising yield per hectare as soon as possible.
- Pure blocks vs interplanted cultivars. Philip suggests small, single-cultivar blocks. He says that, this way, trees are well-pollinated, and harvesting is easier.
- Young trees. Over the years, we’ve established that selecting the right supplier of your new trees is of paramount importance, as is checking the quality of your trees while they are being grown in the nursery and before they are delivered. Philip agrees as this is the only chance you get to start off strong, the first time. His recommendations to guide you through this process is:
- Only buy from SAMAC approved nurseries.
- Before taking delivery, check that the young trees have:
- Been grown in a well-drained medium
- Are between 60 and 120cm tall, measured from top of growing medium.
- All trees of the same delivery have a uniform height and appearance.
- The stem is straight with no visible damage to the bark or stem.
- There is a single central leader.
- Graft unions are no higher than 40cm above the growing medium.
- Graft unions are neat without callousing or weak grafts (Figure 5.5).
- The leaves of the tree are large and a deep green colour without any spotting, fading of colour or imperfections (unlike Figure 5.6). The leaves should be shiny and waxy to the eye
- There are at least two hardened off flushes on each tree (unlike Figure 5.6).
- Graft tape should be removed (unless otherwise requested by the grower).
- There is no visible insect damage to the plant (especially on any new flushes).
- The root system of the tree has developed well. There should be a large number of fine root hairs. These roots should be soft to the touch and light yellow beneath the bark. (Few root hairs or the presence of dead root hairs indicate root rot.)
- The tap root should not be kinked, bent or spiralled in anyway. If this is the case, trees may initially appear healthy, however, the tree can die as late as 3 years after planting.
- The root system should not be pot bound. This can affect development of the tree and is indicative of either too long a period in the bag or bags that are too small.
Figure 5.5 Nursery trees should be of uniform height and appearance with a ‘neat’ graft union
(Source: Tracey Campbell)
Figure 5.6 Nursery trees should not exhibit signs of nutrient deficiency (leaf yellowing) and should have 2 hardened off flushes (unlike the tree on the right which only has one flush)
(Source: Tracey Campbell)
- Tree planting. If the lands have been deep ripped with lime and phosphate ploughed in, then relatively small planting holes can be dug, with dimensions of about 40cm x 40cm x 40cm. Holes can be made either by hand or using a post hole auger, taking care that if an auger is used, to roughen the smooth sides of the hole at planting. Where trees are planted in lands that have not been ripped and ploughed, often the case where macadamias are inter-planted between bananas in KZN, then a large planting hole of dimensions 60cm x 60cm x 60cm is appropriate. When planting in these larger holes, about one third of the planting-hole soil can be filled back into the hole, to ensure that when planting is completed, the planting medium in the bag is flush with the surrounding soil surface. A common error when planting is that the macadamia trees are planted too deep, predisposing the buried stems of the trees to fungal infection (Phytophthora and Pythium being the most dangerous pathogens). Where large holes are necessary, lime and phosphate can be applied to the planting-hole soil and thoroughly mixed into the soil during the planting operation.
Planting into a saturated soil in heavy rain is not recommended. The soil should preferably be moist, not too dry but also not too wet. Trees should be aligned in the centre of the hole and while still in the plant bags, soil should be filled into the hole to ensure that the top of the plant bag is level with the surrounding soil surface. This is best done using a measuring plank, with a V-notch cut into the centre and long enough to straddle the hole, to assist with both the alignment of the tree in the planting line and getting the top of the bag flush with the surrounding soil.
Philip goes on the recommend the use of a 1m2 black plastic mulch around the base of each tree. His motivation is to suppress weeds and limit evaporation. He prefers it to organic mulch (on new trees) because of how ants and termites often move in when dry grass or sugarcane tops are used. If you decide this is the best route, Philip says it is essential that the plastic is covered by at last 2cm of soil and then holes pierced through it with a garden fork.
- Stakes. Newly planted trees with single stems of 80cm and longer can be staked to prevent them being blown to one side by the prevailing winds. Care needs to be taken not to tie the tree too tightly to the stake. Even in windy areas, however, it is preferable to cut these single stem trees back to a height of about 50cm from ground level, in order to stimulate lateral branching below the cut, selecting the secondary or tertiary branches at that point to ensure wide crotch angled branches, making the trees more wind resistant.
- Buck barriers. In areas where buck are a problem, it is also advisable to install some sort of protective structure around the trees to prevent buck damage.
And that’s all for now Folks!
Join us again next month, same place, for the rest of Philip’s free consultation on macs.