Pictured above:Scouting is an important tool in biological controls in the macadamia orchard, helping farmers to better understand pest behaviour.
Thanks to more sustainable solutions for pest control, an improved regulatory environment and a growing body of expertise, a turnaround in crop management strategy is under way in the macadamia sector.
Alison Levesley, general manager at the South African Bioproduct Organisation (SABO), says in the space of just one year, both production dynamics and the regulatory environment around biological controls have vastly changed.
“We were in a different situation this time last year,” she says.
After relentless pressure by CropLife South Africa and SABO, new regulations linked to the registration of biological controls were published in August 2023.
A backlog at the Registrar’s office was also under review, which, Levesley hopes, will reduce the time to get new products registered and approved, and allow the domestic industry to introduce a more robust range of biological crop production solutions in line with markets like the highly regulated European Union.
“This is essential – South Africa’s ability to tap into the single market requires our maximum residue levels (MRLs) for crop protection chemicals to meet their criteria.”
Also on the domestic market, high-end retailer Woolworths is now driving a “zero residue” campaign on all of its products. While the focus is initially on fresh produce, all products will need to meet this criteria by 2035, including macadamias, which are sourced from local farmers.
Healthy nuts for healthy consumers
Worldwide, health-conscious consumers and those concerned about the environmental impact of the food they eat are a key base for the nut market. These consumers are averse to chemical residues on their food.
In a study produced by Australian research company Cavill & Associates, growth in the organic macadamia nut market is driven by increased awareness of the health benefits of organic foods and a growing demand for natural, sustainable products. The study pegs growth in organic macadamia nut production at 5.6% a year between 2024 and 2031.
Brigitte Zablocki, senior vegetable and salads technologist at Woolworths, says zero residue levels prevent continuous, low exposure to harmful chemicals, known to adversely affect human health. “This is true for both people ingesting the food, and those applying the chemicals,” she adds.
Wilma MacPherson, technical portfolio manager at Andermatt Madumbi, says macadamia nuts are promoted as a health food, implying that their production process should align with health-conscious standards.
Kobus Pienaar, technical manager for food security at Woolworths, says the zero residue dictate does not necessarily mean a complete ban on all synthetic crop protection products. “Crop production must make economic sense. Farmers are not expected to stop all pesticide applications to the point where they end up with no crop. Instead, our zero residue programme focuses on integrated pest management (IPM) programmes that rely on farmers having a comprehensive understanding of pest life-cycles and orchard health to ensure an environment where pests can’t thrive.”
MacPherson says using biologicals in collaboration with synthetic chemicals can help reduce the risk of the pest and pathogens becoming less susceptible or sensitive to those active ingredients over time, rendering them ineffective. This means hard-hitting synthetics are still appropriate to beat large infestations.
“The more modes of actions employed against a pest or pathogen, the lower the risk of decline in sensitivity over years of multiple use,” she says.
According to Pienaar, in-depth knowledge and understanding of pest behaviour are critical for the effective use of biocontrols in orchards. “If the pest is not fully understood, then it can’t be controlled,” he remarks.
With this in mind Woolworths and SABO are introducing education programme to help farmers understand the finer nuances of biological crop controls.
“There is already a wealth of knowledge and solutions available, so we just need to make sure farmers are fully aware of what those are,” Pienaar says.
Chemical crop protection is becoming increasingly restricted as consumers demand residue-free products.
Transfer of knowledge
MacPherson warns that farmers should be aware that biological controls are not the same as chemicals, where an application today means a pest has gone tomorrow. “Training, transfer of knowledge, and implementation are critical in helping farmers increase their uptake of biologicals.
“Biological crop production requires a mind shift – where farmers farm their land with nature rather than against it. For example, farmers need to start with the soil, making sure it is as fertile as possible. Some micro-organisms will assist in helping the plants access the nutrition in the soil, especially in some forms that are not directly plant-available. In some cases where soils are depleted, adding a biofertiliser will have a greater effect than when those biofertilisers are applied in optimal soils.”
Mostly, McPherson says, the will to successfully implement a biological crop protection programme on a farm is fundamental to success. “There are many examples of successful implementation. Here, farmers have comprehensive fact-finding missions in place (scouting) to investigate when and also why pests or diseases flare up, and what can be done to prevent this, rather than just spraying chemicals to get rid of every instance, or traditional calendar-based applications.”
The leap towards biological controls is not only being driven by MRL reductions but has become vitally important at a time when many active ingredients used in synthetic crop protection products are being removed from the market.
The Global Harmonised System, which came into effect in September last year, saw the restriction of a long list of ingredients and co-formulants. This includes many contact insecticides, like organophosphates and pyrethroids, and some neonicotinoids that have formed the basis of macadamia crop protection programmes for decades.
The industry, however, still has a long way to go to solve all of its problems biologically.
MacPherson says the sector is growing at a pronounced rate, with macadamias now being planted in areas where they were historically not grown. “We are seeing new pests, either due to invasion from elsewhere, or emerging. The latter includes insects that were traditionally not considered pests but were present in low numbers and are now causing problems in the orchards.”
That meant that each year presented new and different challenges.
“It takes considerable time to develop and register biologicals for a specific pest or disease, meaning we are playing catch-up on a continuous basis,” adds MacPherson. “Many of the chemical actives that have traditionally been registered and used on macadamias are also able to affect those insects which assist the farmers. With many of these being removed from the market, and the time it takes to develop biological controls, we don’t have the full arsenal we need.”
Dr Nico van Vuuren, director of Soiltech, believes it is viable to exclude between 60% and 70% of all synthetic chemicals by implementing a biological-focused IPM programme.
And while some entomologists say having a complete arsenal of biological products might never be feasible considering the changing nature of the natural environment, Van Vuuren says South African macadamia farmers could make good progress with what is already available on the domestic market. “We have a 15ha farm where no chemicals for pest and disease control have been used for the past four years. It’s small in comparison to the industry average, but it gives a good indication of what is possible,” he says.
Double benefit
Active ingredients showing promise in biological macadamia production include a host of bacteria, fungi and plant extracts. It is important to know that most of the beneficial species also promote overall tree health and growth, providing a double benefit.
Growers not only have an expanding list of biological products available, but many organisations in the pest control space are starting to develop tools able to find the right product for a particular pest.
Macadamias South Africa (SAMAC) offers a list of registered products on its online platform SAMAC Integrator, where MacShield provides direct access to a list of options registered against a specific pest or disease on macadamia.
CropLife SA also developed the Agri-Intel database that lists all products registered for use on macadamia trees. Some of the biological insecticides have fungi (Beauveria bassiana, Metarhizium anisopliae), viruses (nucleopolyhedorviruses and granuloviruses), plant extracts, sterile insect technology, and various macrobial predators and parasitoids as active ingredients.
Much progress is being made on beneficial insects like parasitic wasps, which destroy the eggs of stinkbugs, one of the macadamia’s fiercest pests. SAMAC research around controlling stinkbugs by eliminating a bacteria symbiont crucial to their development is showing promise and research is ongoing to determine the best chemicals and sterilisation times for the removal of this bacteria from the egg surfaces.
With the increasing number of solutions on hand, and availability of research, experts agree that farmers have the tools they need to produce a crop capable of competing in a market focused on better human and environmental health.
Written by Lindi Botha
