New Zealand cross-pollination findings

New Zealand cross-pollination findings

Pictured above: New Zealand Scientists Brad Howlett Samantha Read involved with various research project which include in blueberry and macadamia orchards. Picture: Brian Cutting

The research, titled Cross-pollination Enhances Macadamia Yields, even with Branch-level Resource Limitation, published in 2019 by the New Zealand Institute for Plant & Food Research, clearly demonstrates the value of planting different cultivars in a commercial orchard.

The study, led by New Zealand scientists Brad Howlett and Samantha Read, primarily questions the importance of self-pollination versus cross-pollination, and whether it is worthwhile placing managed pollinators in commercial orchards.

Furthermore, they explored whether by increasing the intensity of cross-pollination, final nut yield might be limited by in-tree resources, such as carbohydrate stores.

Using caged and bagged racemes on three cultivars they found strong evidence for self-pollination, but no evidence that hand moving self-pollen within racemes, between racemes, or between trees, improved the final nut set.

“In all cases, however, hand cross-pollinated racemes yielded significantly more nuts. These racemes also produced significantly more developed nuts than open-pollinated racemes – all of the racemes were  exposed to pollinators,” the study says.


The researchers highlighted the lack of research across the many cultivars, saying it is unclear whether self-pollination can happen within florets, or if pollen needs to be moved between florets by pollinators. They also examined how widespread pollination deficits were within blocks of different cultivars, and what effect increasing the amount of cross-pollination across an increasing number of racemes (hand cross-pollination intensity) had on potential nut yields.

“Such information is required to evaluate whether current pollinator management strategies are adequate, or whether new strategies to boost pollination are required,” the study says.

To establish further understanding of the contribution of cross-pollination, self-pollination, and pollination deficits within blocks, and whether cross-pollination intensity affects final nut set, field trials were conducted in Queensland, Australia.

“All experiments were done in orchards within 30km of Bundaberg (360 km north of Brisbane), except for a single trial to assess pollination intensity in 842s, 10km from Gympie (170 km north of Brisbane). All the trees were between seven and 15 years old and the orchards were stocked with managed beehives,” the study said.

Relying on self-pollination in orchards of single cultivars may indeed produce economically viable yields but the findings confirm where steps are taken to increase the potential for cross-pollination, such as mixed-cultivar orchards of known compatible cultivar combinations, and improving insect pollination activity, commercial orchard yields will improve.

New Zealand Scientists Brad Howlett Samantha Read involved with various research project which include in blueberry and macadamia orchards.
Picture: Brian Cutting

“In isolated orchard blocks comprising a single cultivar, the opportunity for cross-pollination is greatly reduced, and yield in these orchards is probably limited to the maximum achieved through self-pollination, regardless of the presence or absence of pollinator activity. Thus, efforts to increase pollination in these orchards through insect-pollinator management may not have a material effect,” the study shows.

Resource allocation

However, and this is where the inquiry becomes instructive for macadamia farmers, the scientists allude to criticism linked to pollination deficit studies of large trees (in which only a fraction of flowers are hand cross-pollinated). The criticism is linked to suggestions that the trees prioritise the allocation of resources, or carbohydrates, to the cross-pollinated flowers at the expense of the self-pollinated flowers. This, they say, exaggerates the potential tree-level increase in yield through improved pollination as it is well known there is a direct relationship between carbohydrate concentrations and retention of immature fruit, and fruit drop might be a response to a competition for carbohydrates.

“Such competitive interactions between developing fruit may result in decreasing nut yields within racemes as the cross-pollination intensity is increased within a tree,” the study says.

But Howlett and Read increased the intensity of hand cross-pollination at the tree scale in the Bundaberg orchards and as a result, were able to quantify the magnitude of this resource-allocation limitation at branch level.

“Increasing the intensity of hand cross-pollinations did decrease the yield difference between cross- and open-pollinated racemes at a branch level, but a significant difference remained between the treatment both at branch and tree levels. This is strong evidence for resource limitation at the branch level in the macadamia, although we did not assess whether resource limitation also operated between branches.

“In our trial, the hand cross pollination of 100 racemes in a tree led to more than 50% of all receptive racemes being cross-pollinated on the day of the trial. Although this is not a complete hand cross-pollination of all racemes, the maintenance of a 70% increase in nut set with this high rate of hand cross-pollination indicates that a significant opportunity remains for growers to increase yields with improved pollination,” the researchers conclude.


The findings of the trial contend that the magnitude of the potential increase through hand cross-pollination “might actually have been underestimated” because of the additional but unknown influence of insect cross-pollination.

In short, the Howlett and Read’s study backs up previous research suggesting steps to increase the potential for cross-pollination, such as mixed cultivar orchards of “known compatible cultivar combinations”, while supporting and improving insect pollination activity, will more than likely improve yields at scale, despite a limit to carbohydrate supply in the tree’s branches.

The South Pacific Ocean country produces about 40 000kg kernel, importing a further 180 000kg annually.

In 2010 it was estimated the country required 100 000 more tree planted to meet domestic demand. With no obvious pests (yet) such as nut borer, among others, New Zealand growers can “easily produce a totally organic macadamia industry”.

Bees – the farmer’s friend

Bees – the farmer’s friend

While the removal of eucalyptus trees makes environmental and water-saving sense, the alien forests provide food for bees on a scale that cannot be matched by the growing number of macadamia trees, resulting in farmers having to up their game on pollination methodologies.

Honeybees play a vital role in human lives and have been kept for thousands of years for the harvesting of honey and to assist with pollination of certain crops. Without honeybees, farmers would not realise the yields to which they have grown accustomed in many agricultural crops.

Without the pollination service provided by honeybees, some pollinator-dependent crops may even fail altogether and the agricultural industry will most likely struggle to exist.

In many areas eucalyptus trees are being removed and replaced with macadamia trees. Although this may be beneficial with a view to water-use and soil management, this practice may also contribute to the reduction in bee numbers. Eucalyptus trees bear strong, fragrant blossoms that attract bees and as these trees’ numbers decrease, so do the bee numbers.

With the dwindling honeybee numbers, farmers cannot rely only on nature for the pollination of crops, yet on the other hand, many are struggling to procure enough hives for pollination.

When looking at pollination in macadamia production in particular, the following aspects should be considered:

  • Macadamia flowers are born on long narrow racemes arising from the axils of leaves or from the scars of shed leaves. The flowers develop on the inside of the tree on mature wood.
  • Flower distribution follows the canopy outward. The raceme cluster comprises up to 500 small flowers spaced along an axis. Each little flower has its own pedicel. The proximal flowers bloom first. These flowers are approximately 1cm to 2cm long and although they are incomplete in the sense that they do not have real petals but four petaloid sepals, they do contain male and female parts.
  • Pollen is shed inside the flower one to two days before it opens and then again one to two hours before opening. When the flowers open, the sepals curl back, exposing the anthers closed over the tip of the style. When the anthers separate, the style breaks free and straightens. The stigma only becomes receptive some time later and because the pollen of a specific flower is generally removed by insects before the stigma is receptive, pollen must come from another flower. Individual flowers remain attractive to insects for about three days.
  • Macadamia flowers open over a six to 12-day period. When contracting bees, it is important to place hives in the orchards during this time. A bee visits each raceme approximately 50 times per day.

While the flowers can self-pollinate, pollinators are essential for good yields. According to literature, bees and leaf roller moths are the major pollinators in macadamias.

When planting macadamias, farmers should also plan for cross-pollination between cultivars. Insufficient cross-pollination may reduce potential yields by 10%. Only 0,0004% of the flowers eventually set fruit.

Good pollination improves nut yield, nut size, kernel recovery and quality. Trees that do not yield fruit grow vigorously and shade out flowers and light, resulting in a negative cycle.

Farmers have three pollination options:

  • The free option

Farmers can opt to rely on feral colonies or on beekeepers who do not charge for bringing their hives to the fields or orchards. This option, however, offers no guarantee that there will be enough bees and that the crop will be pollinated sufficiently.

  • The paid-for commercial beekeeper option

The contractor option might mean higher costs that will add to the input costs of the crop, but the chances of better pollination are much higher. Better pollination means that yields will be higher and in the end, more money in the pocket. Growers should only use bee farmers registered with the Department of Agriculture. Farmers can also contact The South African Bee Industry Organisation (SABIO) to confirm the registration of a beekeeper. It is also advisable to draw up a contract with a beekeeper to avoid any misunderstandings or conflict. It is also wise to book a contractor a year in advance to ensure availability.

  • The do-it-yourself option

Grower-owned beehives give you control. But farmers will incur high start-up costs and it will require learning or obtaining specialised skills and knowledge. Although this is not impossible and even though it should ensure availability, is not easy to achieve at the stocking levels required for optimal pollination.

When keeping their own bees, farmers have different goals from those of beekeepers. Bees are brought into the environment primarily for pollination, and not for extracting honey. Although honey can be a by-product and sold, for most farmers this is not the main purpose of having bees on the farm.

From the macadamia farmers’ view:

Agristar Holdings Group

The Agristar Holdings Groups’ macadamia nut farms in White River implemented their own bee management programme.

“Bees are important for the pollination of macadamia flowers and precisely for that reason, we have our own bee management programme and manufacture our own beehives,” said Adriaan Heydenrych, the entomologist employed by Agristar.

About 400 hives and 120 swarms have been installed on all Agristar farms. Heydenrych, added that well-managed pollination can increase macadamia yield. They use at least two bee colonies to pollinate one hectare. “This makes hive management in the orchard crucial. We therefore employed a dedicated beekeeper,” he added.

Honeybees forage on nectar (carbohydrates) and pollen (protein) of flowering plants, and they require a large diversity of pollen and nectar from different plant sources to be healthy. While some beekeepers may supplement a colony’s food with sugary water, this is not a long-term or healthy option, according to Heydenrych.

Bee health is especially important to them and to support the bees, they plant bee gardens containing a variety of plant species, including basil as well as indigenous plants and weeds, as a forage resource for their bees. In the orchards, they plant bee-friendly cover crops ensuring the bees have food all year round. When bees are pollinating they are not creating honey stores. They also make sure that there is enough water available nearby.

“Just before the macadamia flowering season starts, we cut the flowers and plants in the bee gardens and the bees move to the orchards to forage for food and in return also pollinate the macadamia flowers. Movement of the hives creates stress, so we move the hives as little as possible,” Heydenrych said.

Allesbeste Boerdery

According to Zander Ernst of Allesbeste Boerdery in Tzaneen, they work on the minimum of one hive per ha. “Although some farmers place at least five hives per hectare, we are happy with the pollination we receive,”  he said, adding that when hives are contracted in or moved, it is important to not only look at the number of hives but also the placement.

Allesbeste contracts about 240 hives during the macadamia pollination season, but also has its own. At present Allebeste has 40 swarms and is looking to increase these. “We need more experience in managing our own hives, but it is something we are looking to expand in future as we also rely on bees to pollinate our avocado crop.

“We have permanent steel stands for the hives. Initially the stand were made for five hives, but we reduced the hives to three and found that the bees are now less aggressive.”

Mahela Group

According to Francois Vorster, Director Sub-Tropical Fruit and Wildlife at the Mahela Group, their philosophy is to farm with nature. When negotiating with beekeepers they follow an approach of mutual cooperation rather than a business transaction.

“We try to use beekeepers who are willing to place and leave their hives on the farm for longer periods, even an entire year if possible.”

Some of the hives on one of the Mahela farms. Bees play an important role in the pollination of much of the fruit produced by the Mahela Group.

Mahela also keeps a couple of hives on one of the farms that is serviced by a professional beekeeper and they share the honey on a 50/50 basis. “This is something that I would like to expand as most of our crops need bees for pollination,” Vorster said.

They follow a couple of basic rules. Beehives are placed where they receive early morning sun so that the bees are active in the morning. The hives are placed on stands near water and some can also be locked to protect the bees and their hives.

Vorster says they do not trim weeds in the orchards just before macadamia and avocado flowering time. “We leave the weeds to make sure the bees have enough plants for foraging and an additional food source. After crop flowering, the indigenous bush as well as eucalyptus trees nearby also provide food for the bees.”

They use bee-friendly crop protection productions and if they have to spray, they preferred doing so at night or very early in the morning when bees were not foraging, he added.

Springfield Farms

The Whyte family’s Springfield Farm in the Levubu valley of Limpopo was one of the first in the area to plant macadamia nuts to their orchards. With years of experience in producing macadamia nuts and avocado, they appreciate the significant role bees play in their farming operation.

The Whyte family also owns Green Farms Nut Company, specialising in processing and marketing.

According to Graeme Whyte, they’ve made more than 100 of their own hives using old tyres. Apart from a good recycling exercise these tyre hives also provide a home to many swarms of bees. “The tyres have all filled with bees. We hang them in the surrounding indigenous bush along our macadamia orchards. I think they work quite well and cost very little to make. I have 100 hives at present and plan to expand.

Apart from a good recycling exercise, the tyre hives cost very little to make and provide a home to many swarms of bees.

“Recycling these old tyres, which would have been dumped or burned, has provided living spaces for hundreds of swarms which will multiply and create more swarms. I guess the long-term sustainability of the tyre hive must be determined, but at this stage it is ‘so far so good’ and I feel as if I am doing the bees a favour for a change.,” he said.

Whyte said he also collaborates with beekeepers. “A balance between own hives and the services of beekeepers is beneficial and adds to sustainable bee management in the long run. Beekeepers play a key role in looking after bees and providing a service to farmers, and should be supported for the sustainability of our industry,” he added.

Hive placement

There is more to pollinating macadamias than simply placing a few beehives near the orchards. Placement of the hives should be planned carefully.

When moving hives into an orchard, they should be placed in various locations. Research has shown that the trees closest to the hives will have better nut set, therefore hives should not be placed in one location or in a row.

Beehives should also not be placed or permanently established directly beneath trees. Too much shade will cause the temperature to fall, and bees will become inactive. Bee activity is limited below 13°C so consider placement in areas where the hives will receive early morning and late afternoon sun.

Hives should be placed within proximity of a water source, but not too close to irrigation systems, where the hives can get wet. Low-lying, damp and windy areas should also be avoided. Hives should also be placed on stilts away from ground-predators.


In agriculture, crop yields are threatened by weeds, insect pests and disease. Pesticides are one of the tools farmers use to protect their crops. The success of many crops also depends on sufficient pollination from insects like bees. Protecting crops and ensuring bee safety need to go hand in hand.

According to Barry Christie, the group agricultural technical manager at Green Farms Nut Company, there are a couple of principal factors farmers should consider when protecting their crops. “An integrated pest management strategy focusing on long-term prevention of pests and their damage through a combination of techniques such as chemical, cultural and biological control as well as targeted habitat management like increased plant diversity, should be implemented.”

Farmers can support bee and pollinator health with sustainable, pollinator-friendly farming practices, by planting wildflower strips on the farm, and providing nesting sites or hives for bees.

The following guidelines should be followed:

  • Scout to determine the economical threshold of the insect damage before spraying.
  • Implement biological control methods as part of an integrated pest management system.
  • Before making an application, be aware of any honeybees and hives nearby.
  • Communicate with neighbouring farmers and beekeepers. Many problems can be prevented with better communication and cooperation among growers, pesticide applicators and beekeepers.
  • To reduce bee losses, farmers must adhere to the recommendations on the crop protection product labels. According to Dirk Uys, responsible for horticulture in Africa at Bayer, most problems occur when people apply products outside the registration recommendations. He also said that many of the new products on the market especially focus on the safety of bees.
  • During the flowering phase of the macadamia trees, use products that are bee-safe. Select the least harmful insecticide for bees and spray in the late afternoon or at night.
  • Do not spray in windy conditions when the spray may drift on to adjacent lands supporting foraging bees. Uys warns that the conditions for application must be right. “Once again this comes back to following the label instructions. In most cases when bees are killed by pesticides it is because the product was applied at the wrong time and drifted directly on to the bees or on to flowers on which the bees were feeding.”
  • Avoid using dust products.
  • Do not use herbicides on flowering weeds near the orchards. Weeds should be controlled before flowering or by mechanical methods such as slashing.
  • Pesticide use should be kept to a minimum while there are hives on a property or when hive are installed permanently. Avoid using pesticides near the hives altogether. Most poisoning occurs when pesticides are applied to flowering crops, pastures and weeds. One of the greatest drawbacks to placing bees near agricultural crops is that they may be affected by pesticides.
  • Educate field workers or applicators to ensure they make informed decisions regarding pesticide applications and that they follow the product labels.

Finding dead honeybees is not necessarily an indicator that they were killed by pesticides. It is important to monitor the symptoms of dying bees closely to narrow down the cause.

CroplifeSA compiled a guideline document, which can be of great value to all roleplayers in the industry and can be found at:

There is no singular approach to crop protection. Farmers are in a good position when they have a diverse toolbox at their disposal to safely control or manage pests and diseases. They can minimise damage from pests by using state-of-the-art chemical and biological products, advanced data analytics, and precision technologies.





BASF launches free xarvio® SCOUTING app in South Africa to help farmers optimize crop production

BASF launches free xarvio® SCOUTING app in South Africa to help farmers optimize crop production

  • Free access to world’s number one in-field agronomic problem identification
  • Instant image recognition of local weeds and diseases for key crops using a smartphone application (app)
  • Supports better agronomic decision-making, improving crop health and yield


BASF Digital Farming GmbH, part of BASF’s Agricultural Solutions division, has officially launched its xarvio® SCOUTING smartphone app to support South African farmers and agronomic advisors. It was launched at Nampo, South Africa’s largest agricultural trade show, and was incorporated into BASF South Africa’s stand, as part of its complete offer to the South African farmer. The launch also represents the first commercial market entry in Africa for BASF Digital Farming and smart farming products from its xarvio Digital Faming Solutions range.

The unique xarvio SCOUTING app is free to download and use and has been specifically configured to local agronomic conditions. It enables the fast and accurate identification of significant local weeds and diseases impacting key crops such as maize soybeans, citrus and cereals.

Developed by agronomists and farmers, xarvio SCOUTING uses an advanced plant modelling platform powered by live algorithms that continually improve precision and functionality through machine learning and data sharing. It can instantly detect in-field stress and calculate leaf damage by simply taking a picture with a smartphone. A unique community-based radar function also allows growers to see threats in surrounding fields and notifies them once a threat is close, so they can act

“xarvio SCOUTING is developed for farmers to easily and conveniently identify and document in-field problems. You simply take a photo with a smartphone, then submit to instantly receive the result. With this information in-field issues and problems can be more precisely identified, supporting better, more timely decisions for appropriate treatment,” says Andre Pretorius, Marketing Manager, BASF South Africa.

Saving time spent on scouting expeditions and increasing growers’ and advisors’ access to detailed and beneficial information, xarvio SCOUTING is widely recognised as the most comprehensive, automated, agronomic problem identifier available globally. The app can identify more than 400 weed types and recognise damages caused by more than 400 different diseases, pests, and nutrient deficiencies in over 60 different crops worldwide.

“We are confident that xarvio SCOUTING will be well-received and used in South Africa. The app’s accuracy will continuously improve the more often farmers use it share images of their crops, weeds, diseases, and insect pests. This will ensure that faster and more relevant results are delivered, helping growers optimize crop production,” added Andrew Achille, Regional Commercial Lead APAC & Africa, xarvio Digital Farming Solutions.

To download the free xarvio SCOUTING app, visit Google Play or the App Store.

About BASF’s Agricultural Solutions division

Farming is fundamental to provide enough healthy and affordable food for a rapidly growing population while reducing environmental impacts. Working with partners and agricultural experts and by integrating sustainability criteria into all business decisions, we help farmers to create a positive impact on sustainable agriculture. That’s why we invest in a strong R&D pipeline, connecting innovative thinking with practical action in the field. Our portfolio comprises seeds and specifically selected plant traits, chemical and biological crop protection, solutions for soil management, plant health, pest control and digital farming. With expert teams in the lab, field, office and in production, we strive to find the right balance for success – for farmers, agriculture and future generations. In 2021, our division generated sales of €8.2 billion. For more information, please visit or any of our social media channels.

About BASF

At BASF, we create chemistry for a sustainable future. We combine economic success with environmental protection and social responsibility. Around 111,000 employees in the BASF Group contribute to the success of our customers in nearly all sectors and almost every country in the world. Our portfolio comprises six segments: Chemicals, Materials, Industrial Solutions, Surface Technologies, Nutrition & Care and Agricultural Solutions. BASF generated sales of €78.6 billion in 2021. BASF shares are traded on the stock exchange in Frankfurt (BAS) and as American Depositary Receipts (BASFY) in the U.S. Further information at

Aussie mac estate goes gold for green

Aussie mac estate goes gold for green

In a first for the industry, an Australian macadamia operation has demonstrated

that practices to promote soil health and fertility can significantly reduce greenhouse gas (GHG) emissions and increase GHG removals via soil organic carbon (SOC) improvement.

Carbon reductions refer to a decrease in GHG emissions, achieved by using less fertiliser, chemicals, or energy to produce the crop.

Carbon removals refer to the capture and storage of CO2 from the atmosphere, in this case, via soil carbon sequestration.

Hinkler Park Plantations, a 3,000-hectare macadamia farm based in Bundaberg, Queensland, achieved total greenhouse gas (GHG) reduction and removal of 17,670 tonnes (t) of carbon dioxide equivalent (CO2e) between 2020 and 2021 across its entire macadamia production system through carbon sequestration and by cutting energy and fertiliser use.

This is the equivalent to offsetting the emissions from 4,236 passenger vehicles for an entire year.

Hinkler Park Plantations Queensland general manager and Marquis Macadamias director Clayton Mattiazzi said by going back to basics, Hinkler Park Plantations – also a supplier to the group –  has completely revolutionised its farming operations.

“This time eight years ago, we were struggling with soil health, tree health and yields. By implementing biological farming practices, we have completely reinvigorated the health of our farm and quality of our macadamias,” Mattiazzi said.

“We did this by creating a media of nutrient-rich material to optimise growing conditions for our trees. The key to this was repurposing the excess organic matter within the farm: prunings, inter-row grass clippings and nut husk were all moved back under the tree into soil to compost this material into food for our trees. This activity is supported with large anaerobic composted mulch made from excess farm waste.

“What we have created now is a farm that sequesters more carbon than it produces, preparing us for climate change by building a biologically healthy and more robust farming system.” An independent audit conducted by sustainable food certifier Carbon Friendly found the GHG emissions intensity of macadamia nuts produced at Hinkler Park reduced from 302 to 2,816kg CO2e per tonne of macadamia between 2020 and 2021.

Clayton Mattiazzi at Hinkler Park Plantations in the Bundaberg, Queensland, Australia, where a massive reduction in greenhouse gas emissions has been achieved through biological farming practices.

The Greenhouse Gas Emission Reductions & Removal Enhancements Report found that soil carbon improvement contributed to the removal of 2,935kg CO2e per tonne of macadamia nuts during this period.

Marquis Macadamias growers’ on-farm sustainability initiatives include:

  • Water use efficiency – macadamia farms in sub-tropical regions rely heavily on the area’s natural rainfall. In the Bundaberg region, and in South Africa, growers supplement the rainfall with irrigation sourced from storage dams and boreholes, using the latest in monitoring systems to apply the right amount of water when needed. Marquis has recognised the need for moisture conservation within its orchards, as each tree uses an average of 45l of water per day in winter and 60l of water per day in summer.
  • Healthy soils on farms – compost, woodchip and woodchip manure blends are used to improve soil health and structure on the macadamia farms. Trees are pruned to ensure grass grows between the trees on the orchard floor to reduce erosion. Various cover crops are also planted between the rows to encourage biodiversity, provide a varied diet for pollinators, and encourage micro-organism populations in the soils.
  • Supporting pollinators – bee gardens are developed to provide pollinators with a constant source of food, especially when macadamias are not in bloom. The gardens serve to protect wild bee populations and provide a safe environment where they can flourish and multiply. Great care is taken to ensure that any crop protection chemicals are only used when bees are not in the orchards.
  • Waste minimisation – on farm, growers add the macadamia husk under trees to improve soil health and to compost mixes. When pruning, growers chip branches to use as mulch. All macadamia shell from the factories is used either as renewable fuel to provide energy to various processes including providing heat to dry nut-in-shell, or is milled into stockfeed.
  • Integrated Pest and Disease Management (IPDM) – IPDM is central to successful and sustainable pest and disease management. IPDM involves careful monitoring of crops to identify areas of pest and/or disease activity. If monitoring finds that pest and/or pressure is above critical thresholds, these areas are targeted with various control strategies. Marquis growers focus on maximising the use of cultural and biological control agents, where appropriate, to minimise the use of pesticides.
  • Integrated Orchard Management (IOM) – on farm, growers use IOM, which combines three fundamental pillars of orchard management: drainage, orchard floor management and canopy management. These pillars work together to minimise soil erosion, build soil health, reduce orchard suitability for pests, increase biodiversity and habitat for beneficial insects, and ensure healthy and productive trees.
  • Self-Audit System – Marquis Macadamias has a self-audited quality improvement system in place that all Marquis Macadamias growers must complete at the start of each year.










Optimal yield begins with optimal soil management

Optimal yield begins with optimal soil management

Pictured Above: Leaving natural grasses to grow in macadamia orchards helps keep the soil cool and water requirements low.

Cultivating a crop that is still in its infancy, compared with other extensively researched crops such as citrus, requires a period of trial and error to find what offers the best on-farm outcomes.

Ridging has made its appearance in orchards as farmers realise the benefits of adding an extra layer of topsoil.

Cover crops are becoming more popular to maintain soil moisture and create an alternative habitat for pests, and irrigation practices are increasingly turning to low flow drip irrigation.

While these three practices are often implemented intermittently, research is emerging that suggests the combination of all three offers the greatest benefit.

Strong root system

Netafim agronomist Jovan Erasmus believes a strong root system is required for trees to reach their optimum potential. “This means the soil must allow these roots to develop, without hindering growth. Soil structure is therefore an important consideration, and one that is influenced by multiple factors, including irrigation, wheel traffic and soil cover,” he said.

“Ridges are proving to be far more beneficial than initially thought, since they not only provide a large layer of topsoil, but traffic is forced to stay in the middle of the inter-row and away from the area directly under the tree where the roots are.”

Just outside Nelspruit, Mpumalanga, macadamia farmer Martin de Kock has experienced the benefits of ridging. While this was initially done because of the shallow topsoil on his farm, he has now seen additional benefits.

“It also keeps wheel traffic away from the tree trunk and the roots, preventing compaction. By adding ridges, I’ve exposed the roots to nutrients and water up to 60cm in depth, whereas if there were no ridging, the nutrients would reach only 30cm of the roots.”

A profile hole should be dug to determine if the water is flowing properly through the soil.

Michael Esmeraldo, regional agronomy manager at Netafim in Nelspruit, explained that in orchards he visited, there was a big difference in tree quality between those that ridged and those that didn’t.

“Roots are far more developed when trees are planted on ridges. It also appears that trees grow much faster in the early years, and they start producing earlier. This is because water and nutrient management is more optimal, so the trees get what they need through properly developed root systems and well managed soils.”

Improved drainage

He added that the practice has many other benefits: “There is better drainage so the trees don’t have wet feet, which can lead to phytophthora. You have more control over fertigation applications, and if you fertigate, you can keep those nutrients in that broad layer of soil for longer, which gives the roots maximum time to extract what they need.”

Esmeraldo said while the initial financial cost of ridging was a deterrent for some farmers, just an additional 300kg of macadamia nuts would pay for the hectare’s ridging.

“Considering that yields are better with ridging, you will pay for the extra cost in no time.”

Cover crops

Erasmus noted the positive effect cover crops have on soil structure and reducing compaction in the orchards. This practice also serves as a temperature regulator. “A thick layer of mulch keeps the soil temperatures cooler in the warmer months, preventing root burn. It also shields the finer roots from the cold in winter. This means conditions are optimal for the roots to keep growing, allowing for optimal uptake of nutrients and tree health.”

De Kock therefore allows the natural grasses on the farm to grow between the rows of trees. He said that although this was a big mind shift, the moisture probes told a compelling story. “The soil temperature stays cooler where the grass is long and so I can irrigate less as evaporation is reduced. “The question that I am always asked is what quantity of my nutrients is being stolen by the grass, and the answer is that it doesn’t matter. Studies show it’s between 4% and 7%, which is negligible. I gain a green mulch that builds carbon in the soil and I irrigate 40% less in the orchards where there is proper ground cover with grass.”

In managing the cover crops, a side mulcher should be used to place mown green matter under tree trunks, without having to drive over the root zone. This is done just before the harvesting season to allow easier access into the orchards.

Martin de Kock has seen good results by combining ridging, cover cropping and low flow drip irrigation.


Understanding the way in which water flows through the orchard is a crucial step in determining irrigation schedules. Esmeraldo suggested farmers dig a profile hole one metre from the dripper line, in and between the rows to see how the water moves through the soil.

“You want to ensure that you wet all the roots, because the more roots that are fertigated, the better the tree will grow. We divide the root zone in two: the active zone and the buffer zone and manage them accordingly. If the roots grow up to a metre, then you must irrigate up to 60cm every day, and then once a week wet up to a metre on a longer irrigation cycle. This is how you manage the irrigation to ensure that the roots are irrigated sufficiently but that they also get enough oxygen.

“The profile hole will give you a good indication of how long it takes to wet the root zone to a 60cm depth. This will then determine how long your pulse length should be. If it takes three hours to get to 60cm then you know you should not irrigate longer than this or you will leach the soil.”

Water saving

He said low flow drip irrigation has been found to be the most effective irrigation method for trees in an orchard. This also resulted in a 30% water saving. Water and fertiliser are applied directly to the root zone with minimal wastage, and because water levels are well managed, load-shedding does not have an adverse impact on the trees. The system does not require a lot of electricity to push out large volumes of water that would be required with other systems, which means not only a cost saving, but the whole farm can be irrigated at once.

This system uses two irrigation lines per row, with a dripper spaced every one metre, delivering one litre of water per hour. This results in an average of 2.5m³ per hour per hectare to 3.5m³ per hour per hectare, keeping pace with the trees’ physiological needs.

“Simulating the ideal balance between soil, water, nutrients, and oxygen throughout the sunlight hours of the day will maximise productivity of the tree.”

Netafim agronomist Michael Esmeraldo explains how the age and transpiration rate of a tree determines irrigation cycles.

However, Esmeraldo cautioned farmers not to over-irrigate orchards. “With this system, farmers might be inclined to want to irrigate more because they are not necessarily seeing the water in the orchards. But if the water is running out of the ridges it means nutrients are being leached. This system is designed to give the tree exactly the amount it needs, so there shouldn’t be any water pooling up. We are also starting to realise that macadamia trees need far less water than initially thought.”

Irrigation schedule

De Kock bases his irrigation schedule on readings from the on-farm weather station and moisture probes. He adjusts his irrigation every three days according to the soil’s needs, based on these readings.

“This does not take the physiological stage of the tree into account, so I need to consider this too to ensure the trees get what they need for their stage of growth.

“Relying on a soil probe can also be problematic since the readings are very much dependent on where the probes are placed. Knowing the transpiration rate based on the age of the trees and the canopy size, it is far easier to irrigate accurately and eliminate any vast fluctuations.”

Flow metres are in place on all the irrigation lines on De Kock’s farm, which alerts him to any irrigation problems.

“The design of the whole system is important because it can not only alert you to problems, but easily identify where the problems are. Because the irrigation is divided into smaller blocks of one or two hectares, each with its own mother line from the pumphouse, if there is a problem I know where to fix it. So not being able to physically see the water being sprayed in the orchards is not a problem.”

De Kock applies fertiliser with every irrigation cycle and each tree receives 1.6mm per day. “It’s not a lot of water, but it is possible because of the low flow drip irrigation system and the way in which it evenly distributes water.”

Going one step further, he has implemented sub-surface drip irrigation. He said that this keeps the pipes cooler, meaning that the first water emerging from the pipes is not overly hot, as it would be if the pipes were lying in the sun. This hot water would then burn the finer hair roots growing close to the surface. The fact that the pipes are buried also means rodents don’t chew the pipes.

Since implementing the low flow drip irrigation, ridges, and cover crops, De Kock has seen the health of his orchards improve, with trees bearing nuts at a far younger age. “I am reaping the rewards of this system,” he said.

Mayo Macs geared for successful 2022 harvest

Mayo Macs geared for successful 2022 harvest

Each year Mayo Macs meets with its suppliers before the processing season to discuss market trends, international demand and the latest in best practice methodologies both in the factory and on the farms.

As one of the first South African macadamia processing companies in the country, this year’s event included tours of the group’s recently upgraded processing facilities.

Grower returns

Mayo Macs Chief Operating Office, Cobus Venter, said that since the company was restructured in 2021 to become a wholly-owned grower concern, the information days were geared towards the improvement of grower returns.

“One of our strengths at Mayo Macs is our comprehensive technical shareholder-grower support and communication strategies. Our technicians are just a WhatsApp message away. During the information days we also give the farmers practical examples on scouting for pests, maturity testing in the orchards, the fundamentals of orchard management, the correct applications of compost and improved record-keeping.  Each day culminated in tours of the processing facilities which highlighted how pragmatic Mayo Macs is in its view of grower capital and how the recent factory upgrades translated into an immediate improvement in grower returns,” he said

Mayo Macs recently concluded numerous information days at their processing facilities in Mpumalanga and Kwa-Zulu Natal ahead of this season’s harvest to bring growers up to date on best orchard management strategies and improved hygiene and cleaning requirements on their farms.

Food safety

Heinrich Grobler, head of food safety and quality at Mayo Macs, brought the farmers up to date on the very latest developments linked to Supplier Quality Assurance (SQA), microbial food pathogens’ association with macadamias and the evolution of food factories, and the necessary commitment towards social, ethical, and environmental best practices.

Interestingly, compost, chicken litter and/or kraal manure should not be applied to trees prior to or during harvest as they are a potential source of Salmonella spp. a high-risk food bacterium,” he told them.

Mayo Macs recently concluded numerous information days at their processing facilities in Mpumalanga and Kwa-Zulu Natal ahead of this season’s harvest to bring growers up to date on best orchard management strategies and improved hygiene and cleaning requirements on their farms.

In fact, before manure is applied in the orchards a sample should be tested by an accredited laboratory before any on-farm application.

“Any manures should rather be composted with other organic materials to a temperature of 55-60°C which is the thermophilic range in which pathogens and weed seed are killed off, but beneficial organisms remain intact. It is important the compost heaps are turned when a temperature of 60-65°C is reached. The temperature should not exceed 70°C. Three turns are adequate to produce safe, good quality compost for application in the orchards,” Grobler said.

In a bid to improve on-farm hygiene and cleaning, the company has offered its growers hygiene kits at a reduced price.

“The products were selected to meet the highest food safety standards and include water bath disinfectant, and products for cleaning workers’ hands as well as equipment such as dehusking lines, conveyor belts and drying bins,” Venter said.

Jaap van Oenen, senior trader at Global Trading and Agency

Global Trading and Agency senior trader, Jaap van Oenen briefed the gatherings on marketing strategies for the year ahead saying he felt confident sales would be good in 2022 as there was no carry-over stock from the 2021 harvesting year.

Venter said he acknowledged the future looked very different from the past. “The changing world in which we live means we must extend beyond the traditional communication narrative of input costs versus revenue-per-hectare to one of shareholder-grower inclusivity and food safety.