Pictured Above: Hugo Bester
Macadamia farmers across South Africa are hailing the parasitoid wasp, Trissolcus basalis, as a deadly strike weapon in their war on stinkbugs. Improved nut quality is proof of the insect predator’s success, they say.
While Trissolcus basalis might be just half the size and width of a housefly, the parasitoid wasp is punching way above its weight in the fight against the stinkbugs so prevalent in South Africa’s macadamia orchards.
Lyle Wichmann, who has orchards inland of Zinkwazi Beach on the KwaZulu-Natal North Coast, says in the three years since he introduced the wasps into his 20- to 30-year-old trees, unsound nut percentages have dropped from 4%-6% of his annual harvest to less than 1%.
Pictured: Lyle
“Our initial attitude to pest control in our orchards – which had been severely neglected before I took over – was to go harder with chemical spraying. And yes, we would knock down the stinkbugs and other pests, but they would be back within days of the application,” he said.
Dr Brent Chiazzari, who is the Farmers Agri-Care Crop Advisor for that region, said the exponential growth in bio-security measures to control pests in the domestic orchards had taken off in the country since 2021. “Farmers are responding to international pressure to reduce harmful chemical use in their orchards in compliance with international certification standards such as Global Gap and the European Union’s Green Deal. They are also seeing the benefits of biosecurity on the growth of beneficial insect populations inside and outside their orchards.”
Dr Brent Chiazzari
Wichmann said a wake-up call for him personally was standing in his orchard during flowering and hearing nothing, just silence. “Now, it’s the opposite. The orchards are humming and buzzing with life,” he said.
So how do these tiny black wasps with four transparent wings go about their business, and why are they in the frontline in the fight against stinkbug infestations in macadamia orchards?
Hugo Bester, Technical Advisor for Koppert Southern Africa – a Dutch-based biological pest control company – opens a video on his smartphone, showing a small black-winged insect darting back and forth over a cluster of pale stinkbug eggs on the back of a macadamia tree leaf. “Look how excited she is,” Bester says. “She’s laying an egg in each of the stinkbug eggs; in a few days the eggs will start to discolour, which indicates that the stinkbug nymph is dead and the Trissolcus basalis larvae are feeding on them.”
The female wasp guards her brood until they hatch, and as soon as they do, the newly emerged males and females will mate, ready to start their lifecycle all over again. Because the insect is a strong flyer it distributes well in the orchard, Bester adds.
He then demonstrates how the wasps – branded as Greenshield – are transported by courier directly to farmers in small cardboard “bottles” from Koppert’s South African laboratories in Lanseria.
The deliveries are synced with other synergistic soft and targeted pest control methods, including sprays and drenches. “All of us work as a team to make sure the different remedies are delivered at the right time and in the right way. Timing is key,” he said.
Each bottle contains a “sugar patch” as food for the little creatures and is sealed with a white paper disc. Every bottle has a rubber band attached.
Bester removes the seal revealing a small hole, makes a loop with the rubber band, and attaches the container to a branch halfway up the macadamia tree. “One bottle contains 100 wasps, enough to cover 1ha. Ideally the tube is placed in the shade of the tree canopy, wedged between branches, and first prize is to have them near a batch of stinkbug eggs, but that’s not essential,” he said.
But timing the release was crucial.
Parasitised Eggs
“We recommend the first release in August and September depending on the season and the cultivar. The presence of stinkbug adults or eggs is not essential, but rather helpful, to build parasitic wasp populations. The wasps should be released in the middle of each hectare block every four to six weeks at 100 insects per hectare.”
Chiazzari hailed the wasps as integral to biosecurity strategies in macadamia orchards as they effectively controlled the egg phase of the stinkbug’s life cycle. “Greenshield is not a stand-alone control method of stinkbugs. We still use compatible chemical sprays in our arsenal to control the pest, but they are key,” he said.
Bester added that chemical sprays were necessary, particularly in the first year, to lower the stinkbug pest pressure.
The list of compatible chemicals includes:
Thiamethoxam
Pymetrozine
Imidacloprid
Methoxyfenoxide
He said scouting remained a vital part of a successful pest control programme. “Scouting for parasitised and non-parasitised eggs can indicate the success of the Greenshield releases. The non-parasitised eggs are cream-coloured while the parasitised eggs are brown or black,” he noted.
Wichmann said another plus factor was since the release of the wasps into his orchards, he had been able to slash the active ingredients in the chemicals he used. “I used to apply products with about four to five active ingredients, now it’s one or two. That is a huge cost saving and its better for the environment,” he said.
Dustin Cooper, whose seven- to eight-year-old orchards are also in the Darnall/Zinkwazi area, said in his mind the wasps were like security guards patrolling his orchards. “I think about them chipping away at the stinkbug numbers in the background. I might not be able to see them, but I know they are there. Doing their work. Guarding the trees,” he said.
Written by Colleen Dardagan
On the day The Macadamia magazine went to print, SAMAC CEO Lizel Pretorius confirmed that South Africa’s macadamia exports were no longer subject to the additional 30% reciprocal duty into the United States.
No fanfare – as when the tariffs were first imposed by US President Donald Trump – just a summary of the implications of the Executive Order and two annexures setting out the amendments to the US Harmonised Tariff Schedule (HTSUS) and the official listing of products exempted from reciprocal tariffs, including macadamia nuts.
Pretorius does add, however, that formal incorporation of the changes is still pending and that SAMAC would continue to monitor developments while keeping its members informed.
In a New York Times article on November 16 by Ana Swanson, the “walk back” on imports, which included beef, coffee, tomatoes and bananas among others, is what “critics say is an admission that the tariffs raised prices in the first place”.
“They walk back one of the president’s signature policies, the sweeping tariffs that he has suddenly paused, raised and lowered in recent months, causing chaos for trading partners and international businesses,” the article said.
While the White House is alleged to have said the tariffs were no longer needed, given the “substantial progress it had made in its trade negotiations”, Swanson hazards that the steps also “appear motivated by a rising concern inside and outside the White House about consumer prices”.
“Though Mr Trump campaigned on lowering the price of groceries, continued elevated inflation has weighed on his approval ratings, and concerns about affordability helped propel Democrats to wins in elections across the country last week.”
There is no getting away from it: Trump’s Make America Great Again strategy has cost South African macadamia, citrus and wine farmers dearly, but it can also be said that these domestic industries might have been bitten once and now they are twice shy!
In this edition of The Macadamia – the last for 2025 – we look at how the industry has responded to the tariffs; how alternative markets have been sought, and how the investment in processing infrastructure in China has local players watching warily.
Scores of small businesses are opening across South Africa’s macadamia industry as a side hustle to keep cash flow healthy and their macadamia operations viable, despite macro shocks such as the American tariff fiasco.
In this edition we take a sweeping look at these businesses, which range from coffee shops to fire briquette manufacturers, all with macadamias at the centre of their business model.
To celebrate the launch of the latest Macadamia Magazine and the exciting new macadamia products featured in this edition, we’ve teamed up with Shisa Briquetts, The Nutty Kitchen, Green Farms Nut Company, Nathi Skin Care, Simply Macnificent and Giraf Macadamia to give one lucky winner an incredible Macadamia Product Hamper worth over R3,000.
A true celebration of local flavour, innovation and macadamia goodness!
While the authors acknowledge there are other environmental benefits from reduced tillage systems and intercropping practices, they say greenhouse gas sequestration figures are not clear-cut.
As a non-profit and politically independent organisation, agri benchmark provides comprehensive information and advice on crop production systems worldwide.
Dr Yelto Zimmer, Dr Joachim Lammel, Professor Ludwig Theuvsen and Barry Ward recently published their study titled “Regenerative agriculture and climate change mitigation – high expectations, low success” in the peer-reviewed academic journal EuroChoices. The study can be downloaded at: https://tinyurl.com/yz3dpfn2 .
According to the findings, practices such as intercropping and reduced tillage are feasible only to a “limited extent” and may even reduce yields under certain climatic conditions. “The expected economic benefits are often based on unrealistic assumptions, and the lower yields can even lead to indirect land-use changes that can negate carbon sequestration,” the authors say.
Further, they fear that the focus on regenerative methods might distract from the real issues: “Whether intentional or not, we see a risk that policy-makers, industry and farmers will be fascinated by the fancy term, while not addressing the really important strategies to mitigate greenhouse gas emissions, such as the efficiency of nitrogen use in agricultural production systems. Our impression is that the concept of regenerative agriculture is so attractive to agricultural actors because it focuses on the sequestration of greenhouse gases and therefore can, at least in theory, become a source of income for farmers through the sale of certifications.”
While regenerative agriculture methods may have other benefits such as soil health and improved water retention, researchers say the system’s potential for carbon sequestration through is over-stated.
Improving nitrogen efficiency as a guiding principle
Rather than focusing on regenerative agriculture as a strategy to reduce greenhouse gas emissions, the academics say improving nitrogen use efficiency is a more effective approach to cut back on the carbon footprint of agricultural products. The use of mineral nitrogen fertilisers is responsible for around 80% of the greenhouse gas emissions linked to crop production and it goes without saying that effective fertiliser applications reduce input costs and improve productivity.
Further, unlike regenerative methods, improving nitrogen efficiency provides stable and measurable results without the need for farmers to accept yield losses or to remain dependent on permanent financial compensation from governments.
The researchers believe this model is a much more sustainable long-term strategy that makes economic sense while simultaneously making a reliable contribution to climate change mitigation.
They also call for “critical dialogue” on the issue. “We hope that in the end, agricultural stakeholders will be aware of the limitations and shortcomings of the key elements of regenerative agriculture in terms of reducing and sequestering greenhouse gases. On this basis, they will be in a better position to contribute to the much-needed improvement of the greenhouse gas balance of global crop production,” they say.
While macadamia farmers in the irrigated north saved money on Eskom costs, growers in the south say heavier than usual rainfall increased disease pressure in their orchards.
As rainfall in the first four months of 2025 exceeded the average annual rainfall for KwaZulu-Natal, macadamia farmers are reporting increased pest infestations and flower disease in their orchards.
Coupled with a dry start to the 2024 season, cloudy days have also impacted yield, with access to orchards a massive challenge during the current harvest.
Local macadamia experts say extreme rainfall, particularly along the coastal regions of the province, has augmented outbreaks of fungal and flower diseases such as Botryosphaeria, phytophthora and husk rot, with late rains in the spring of 2024 delaying the flowering on some of the tree varieties.
One expert, who asked not to be named, said wetter conditions and out of season rain had made pest control difficult as tractors were unable to get to the orchards and the lifecycle of some pests had changed in accordance with the climatic conditions. “It becomes harder to control the borer complex, in particular,” the expert said.
One of the key standouts for effective orchard management over the past three years, the expert added, was managing the influence of the climate on tree health and yield. “Good orchard practices still play a significant role in good yields, but climatic conditions are now more prevalent as an influencing factor than ever before. We are advising macadamia farmers to improve access to their orchards, and drainage; and to understand that managing effectively is not calendar-based but being able to read the conditions and respond accordingly.”
Monitoring irrigation, and using probes, was crucial and one was not effective without the other. Also, farmers are advised to use biological control as an effective pest control method when it’s impossible to apply chemicals because of wet weather.
Johan Boonzaaier, Chief Executive at the Impala Water Users’ Association in Pongola, said from January 2024 to December 2024, rainfall in the region measured 688mm. “From January to May this year, we have already measured 691mm”
Chairman of KwaZulu-Natal’s South Coast Macadamia Farmers’ Association Quinton Elliot said the region had 1 000mm of rain between January and April. The annual average rainfall for the area is 1 100mm. In the same period in 2024, he said farmers on the South Coast measured just 537 mm of rain. The crop, he said, was 5% and 10% down on previous annual harvests – however, it was still early into the harvesting season, which usually ends in August and September. The lower yield, he added, could be attributed to an excessive number of cloudy days during the growing season.
“This year we have had much higher incidences of mould and it has been a challenge getting the harvest in as the orchards have been so wet.”
Interestingly, he added that here and there individual trees – some as old as 20 years – had died from the extreme wet weather. ‘It wasn’t widespread, but it was interesting that some trees just fell over.”
Pongola macadamia farmer Laurie Brecher said the higher than usual rainfall had allowed for savings on irrigation costs. “We didn’t have that much in the way of increased disease or pest infestations because we were able to manage the water in our orchards. In fact, we didn’t have to irrigate for two months, which meant we saved on Eskom costs. The challenge for us wasn’t in the orchard but rather once we had harvested. We started harvesting at the end of February and because the nuts were so wet we had to leave them in the drier for a couple of days longer to make sure they were dry enough before sending them to the processor,” Brecher said.
As South Africa’s macadamia industry moves into a recovery phase after a three-year price low, farmers are urged to boost their feeding and pruning programmes. “With rock bottom returns since 2022, we advised growers to do the basics right, use reputable products from loyal and reliable companies, and to make sound economic decisions rather than look over the fence to see what the neighbour is doing. We also urged them not to cut back on the non-negotiables like fertiliser, pest and disease control and pruning,” the expert said.
But now that prices were coming back farmers should pick up on optimum orchard management and integrated pest management practices.
Both Elliot and the expert agreed that macadamia farmers, particularly in Kwazulu-Natal, which had seen exponential growth in new orchards since 2015, were adopting some of the most modern and up-to-date management methods. “Between 2015 and 2021 it was all about developing new orchards and tree-planting. Now we are seeing the increased use of technology, good record keeping and precision agriculture becoming more common. The farmers are also questioning remedial recommendations, rather than just doing what they have always done,” they said.
Farmers were also interested in learning more about the crop and how to be better and more economical, from tree health right the way through to harvesting and curing the crop.
“Hard times make good farmers and there have been some casualties since 2022, but I don’t think that is necessarily a bad thing,” the expert said.
Article
Colleen Dardagan
