Vegetables & Fruit November/December 2021 by Vegetables & Fruit

SINCE 1988

NOVEMBER • DESEMBER 2021

Dormancy and flowering in litchi R40,00

(BTW ingesluit) ander lande uitgesluit (Including VAT) other countries excluded

No 204

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Spring, summer and autumn harvest. Good heat tolerance. Semi globe shaped heads with excellent internal quality. Early maturing. 75-85 days in summer.

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25 Edition 204

ISSN 1015-85 37

VOORBLAD

NEWS

New study reveals ethephon’s role in regulating dormancy and flowering in litchi

4 Top ten olive oil award winners 4 Five years of support to new farmers celebrated 5 New chairperson for Fertasa 6 Faith takes the gold 6 New GM for SABO

SUBTROPICAL FRUIT 8 A new avocado order for consumers

EDITORIAL Willie Louw (Group editor)

8 New pecan production guideline handbook released 9 Avocado treatment programme with Galilee Export 10 Relief to farmers in need

Carien Daffue (Editor) 018 293 0622 info@mediakom.co.za PO BOX 20250, Noordbrug, 2522

12 The world of avocados 15 WE ARE NOT ALONE – The soil, microbes and human health 18 22 24

New study reveals ethephon’s role in regulating dormancy and flowering in litchi Plant nutrition concepts in nut crops Will dragon fruit take over as super fruit?

NETS 25 Verbouing van gewasse in hidroponiese stelsels 28 Shade netting makes the difference

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GENERAL

34 ARC aids in keeping the yellow dragon at bay in citrus orchards

DESIGN Mercia Venter studio.chatnoir@gmail.com

Bly ingelig en volg ons op Facebook. Keep up to date and follow us on Facebook. - Groente en Vrugte/ Vegetables and Fruit - www.facebook.com/GroenteenVrugte/

30 Bucking the trend

31 Fighting the mealybug

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GROENTE & VRUGTE | NOVEMBER • DESEMBER 2021

TOP TEN olive oil award winners The 2021 Absa top 10 olive oil awards were recently celebrated. The partnership behind the awards dates back to 2013, when SA Olive and Absa joined forces to launch the Absa top 5 olive oil awards as an extension to the annual SA Olive Awards. Since 2017, it become known as the Absa top 10 olive oil awards.

or the prestigious recognition of the pursuit of excellence by South African olive oil producers, it is required that ten different producers make the winning extra virgin olive oil (EVOOs). This reaffirms the intent to support the development of the South African olive oil industry by maximising exposure and opportunities for local EVOO producers. In the 2021 edition of the SA Olive Awards which was held in August-September, 113 South African EVOOs were assessed by a judging panel through a strictly controlled blind tasting. Out of the 30 gold medal winners, the highest-scoring oils became contenders for the Absa Top 10 Olive Oil Awards. These olive oils were judged and the winners were selected by a panel of revered tasters and local experts, led by panel leader Dr Aldo Mazzini who had flown in from Italy to preside over the judging. The accolades were awarded to: • Willow Creek: Willow Creek Directors Reserve EVOO • Lions Creek: Lions Creek Karoo Blend EVOO • De Rustica Olive Estate: De Rustica Estate Collection Frantoio

• • • • • • •

Olive Boutique: Olive Boutique Frantoio Mardouw: XXV Intense Porterville Olives: Andante Intenso Serrado: Serrado EVOO Lapithos: LapithosFamily Reserve Rio Largo Estate: Rio Largo Premium Kleinbergskloof Olive Estate: Kleinbergskloof Olive Estate Blend

SA Olive Chairman, Nick Wilkinson remarked that the 2021 season had delivered olive oils of excellent quality, many of which had already been recognised internationally. “There is undoubtedly a growing space for top quality oil produced by smaller producers with smart attention to detail. It’s time to educate consumers to appreciate the taste of good olive oil along with its many health benefits. We need to push our local consumers to buy local and recognise quality over quantity. The perceived premium price is a low price to pay for our well-being and keeping South Africans employed.”

Five years of support to new farmers celebrated

n the 2021 summer crop season, FarmSol paid over R18 million in profits to smallholder farmers. This has been made possible by FarmSol’s partnership with the South Afri can Breweries. To develop a farm, one has to start somewhere. And the way to start is by creating partnerships, linking dreams to the barren land. Initially, the partnerships will be few and far between. Still, then as they slowly increase in number and impact, the dots start to connect to create what would hopefully be a sustainable enterprise for the farmer, employees and the nation. After all, food production and food security are basic human rights for all. FarmSol is celebrating five years of supporting new farmers. “I have been

steering the ship at FarmSol for the past three years,” says Aaron Kole, Managing Director for Farmsol. “We faced seve ral challenges, including droughts, flooding and the Covid-19 pandemic. What an exciting journey it has been. “At FarmSol, we are particularly proud of the contribution of each one of our farmers and the team has made to the South African agricultural landscape. It's been nothing less than hard work, dedication, commitment and effort. However, our farmers also showed incredible resilience to keep their heads up against all odds and keep doing what all farmers do, namely get up, put up with their challenges, grow crops and keep doing their best to produce food for the nation,” Kole concludes. Aron Kole is the Managing Director at FarmSol.

VEGETABLES & FRUIT | NOVEMBER • DECEMBER 2021

New chairperson for Fertasa The Fertilizer Association of Southern Africa (Fertasa) announced the appointment of the newly elected chairperson to the board, Henk le Roux.

“A

to promote the responsible and sustainable use of fertilisers,” says Henk. He urges all the relevant organisations that have not yet joined Fertasa’s growing number of members to join them and add their valued inputs to ensure the long-term success of food security through a responsible agricultural Industry. Le Roux was born and raised in the Northern Cape but matriculated in Port Elizabeth. He completed B. Agric. at UOFS, a B Comm (Hon) (UNISA) and MBA (Potchefstroom University). He started his career with Agrico in Bloemfontein and later moved to Natal, joining Zululand Irrigation and Barlow Hand ling. In 1999 he joined NWK, where he has been involved over the past 22 years in the liquid fertiliser factory, fertiliser marketing, grain trade, trade general and mechanisation. He currently serves in the organisation’s management team in the position of senior manager of fertiliser and projects.

SCAN ME

griculture is my passion. I am learning every day and with all the knowledge from industry leaders, colleagues and agri-friends in the fertiliser industry, this career is the best I could have hoped for,” Le Roux said. Over the past 20 years, Le Roux has been involved with the agricultural company in North West, NWK, in liquid predisposition division and fertiliser marketing. “Fertasa plays a vital role in the fertiliser industry in Southern Africa, especially in our involvement with critical role players in the industry, and specifically as far as liaison with the Registrar of Act 36 of 1947 to enhance and protect the interests of our members is concerned. “We are privileged to have a very committed board, CEO and members of committees to ensure that we fulfil our vision and mission, to be the representative voice for the industry and

Henk le Roux

FERTASA, FERTASA , CERTIFIED CERTIFIED CREDIBILITY. CREDIBILITY.

ITS MEMBERS ARE COMMITTED TO THE PROMOTION OF FFERTASA ERTAND ASOIL S AFERTILITY , CEAND RTENHANCED IFIED CNUTRITION. REDIBILITY. SUSTAINABLE PLANT

Fertasa strives to provide information on fertilizer and crop related topics. Apart from assistance with fertilizer applications, queries relating to fertilizer usage, plant nutrition and soil fertility usage, plant nutrition and soil fertility are referred to our Technical Advisers or Subject Matter Specialists for their expert opinions and advice. Member companies and others are encouraged to share their experiences in proven techniques and novel approaches in ensuring social, environmental and economic sustainability for all.

Tel: +27 (0) 12 349 1450 | Fax : +27 (0) 12 349 1463 Email: general@fertasa.co.za

FERTASA MEMBERS ARE COMMITTED TO: Ÿ

A code of conduct.

A set of standards audited by an independent compliance management body.

Quality products.

Relevant scientifically-based recommendations.

Continual learning and improvement.

Complying with all legal requirements. FERTASA Fertilizer Association of Southern Africa

www.fertasa.co.za

Faith Nogemane

Faith

takes the gold Faith Nogemane, a general worker from Wildekrans Wine Estate, Botrivier, became the 8th winner of Agri's Got Talent (AGT) recently. Due to the Covid-pandemic, the final event was live-streamed via social media platforms and saw the finalists bravely battle it out with heart and soul.

onel Radloff from Diemersfontein, Wellington, was second, and Jack Jonas, from CRI Citrus Foundation Block, Uitenhage, took third place. Faith, who won the judges over with her performance of ‘Amazulu’ and ‘Stand up for love’ said that the event had a huge impact on her. “We learned so much during the event and although I was motivated to win, I was constantly aware of how talented the other finalists are.” Apart from being a singing competition, AGT is also a social development programme for agricultural workers in the fruit and wine industries. The programme is a joint venture between Hortgro, the Citrus Growers’ Association, Vinpro,

New GM for SABO

the South African Table Grape Industry and the Western Cape Department of Agriculture. All the finalists received voice, stage and media training. The finalists also get make-overs, including clothes and a selfcare package, and self-development workshops hosted by Procare. These workshops specifically aim to grow finalists’ self-awareness and confidence through soft skills development, such as conflict resolution, money and time management. These skills are invaluable for potential music careers but also in the work context.

Andrew Bennet

he South African Bioproduct Organisation (SABO) appointed Andrew Bennett as General Manager to assist with the day-to-day operations of SABO SABO was established in 2013 as a brainchild between the then Department of Agriculture, Forestry and Fisheries, various research institutions and the agricultural industry. The objective was to improve the standards of bioproducts in the market to protect both the supplier and the growers using these biological products. The purpose of SABO is to develop the agricultural bioproduct industry in South Africa and regulate participants’ activities in accordance with high ethical and science-based standards. SABO aims to grow the industry by educating the benefits of the products and services available in the industry. Agricultural private companies, universities and individuals contribute to SABO’s current 37-member base. Bennett will assist with the day-to-day operations of SABO, including supporting and overseeing the activities related to its working groups and creating initiatives to pro-

mote the biological industry. Clarifying the regulatory process for biologicals is high on the priority list. Previously, Bennet was with Monsanto (22 years), where he led their Technology Development team in Asia and Africa. He has an MSc degree from the University of the Witwatersrand, a Post Graduate Diploma in Marketing Management and various certificate programmes in Trademark and Patent Law from UNISA. He has also been active in various industry bodies such as the Insect Resistance Action Committee and SANSOR’s innovation committee.

VEGETABLES & FRUIT | NOVEMBER • DECEMBER 2021

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SUBTROPICAL FRUIT

A new avocado order for consumers S

outh Africans like avocados, and they like to eat them all year round. They will even pay a premium for imported avocados, but this is expensive not only to them but also to the environment. So, fuelled by increasing awareness around health, care for the environment and the attendant costs of paying for imported produce, ZZ2 Afrikado is launching its Harmony Avs onto the SA market, thereby making 12 hand-picked avocado varietals available in season, all year round. While South African consumers are mostly familiar with the Hass and Fuerte varietals of avocado, ZZ2 is releasing ten other varieties to buy locally grown produce while it is in season. They have the added benefits of supporting their local market, knowing where their food comes from and knowing that it has not travelled far to reach them. ZZ2 has planted trees at various altitudes, which come into season at different times. By implementing the principles of its Natuurboerdery (farming with nature), working holistically with nature and with the elements of sunlight, water and soil, ZZ2 has nurtured the trees in terms of their welfare as well as that of the environment, for example, beehives in the orchards. The aim is to yield the resulting range of ZZ2 Harmony Avs that are

available for in-season consumption in South Africa. The varieties include Hass, Maluma Hass, Lamb Hass, Fuerte, Pinkerton, Ettinger, Ryan, Galil, Edranol, Itzamna, Simmonds and Shepard. Coinciding with Natuurboerdery thinking, a new movement – The Harmony Way – was born and sponsored by ZZ2. The Harmony Way features valuable information written by some of South Africa's leading influential food and health bloggers, including Christy Ann, Amilinda Wilkinson (The Little Hedonist), Crystal Espin, and Jeremy Proome.

New pecan production guideline handbook released T

he ARC-Tropical and Subtropical Crops (ARC-TSC) released the third edition of the Production Guidelines for Pecan. South Africa’s pecan industry is rapidly expanding, a situation that has given rise to many opportunities and challenges. One of these challenges is the need for accurate information to ensure optimal pecan production despite changing climatic patterns.

Launch of the latest edition of the Production Guidelines of Pecan publication: Dr Karin Hannweg, Dr Elliosha Hajari, Ms Lucinda Rabie, Ms Estelle Nieuwenhuis, Mr Arthur Sippel, Dr Yolisa PakelaJezile and Mr Oscar Maphanga.

New entrants into this market need information regarding climatic requirements, cultivars, nutrition, pest and disease control and marketing. Since the last pecan handbook was compiled in 2008, a large body of research has been undertaken to improve recommendations for pecan production under current conditions. Therefore, the ARC-TSC, together with the producers association SAPPA as well as other stakeholders e.g. university partners and industry specialists, worked together to produce the updated Production Guidelines for Pecan. The aim was to present the material in a reader-friendly manner without neglecting the scientific principles on which various practices are based. It is their hope that, whether the reader is a producer, farm manager, potential future producer, student, university professor or just someone interested in growing a few pecan trees, the information contained within the 27 chapters of this new edition will be useful. By applying the principles of sustainable farming as set out in this book, the reader will surely make a success of their pecan tree growing effort or business. The new handbook can be ordered through the ARC’s website.

VEGETABLES & FRUIT | NOVEMBER • DECEMBER 2021

SUBTROPIESE VRUGTE

Avocado treatment programme with Galilee Export Save Foods is an Israeli-based agrifood tech company focused on developing and selling eco-friendly products specifically designed to extend the shelf life and ensure the safety of fresh fruits and vegetables. They recently announced that it is beginning a large commercial treatment programme with Galilee Export, a leading Israeli avocado packer.

alilee is the second-largest exporter of fresh produce in Israel, managing over 9 000 hectares of farmland, growing a wide range of fruits and vegetables for customers around the world. Avocados are their leading product, and Galilee accounts for nearly 50% of Israel's total avocado exports. Galilee also exports other fruits and vegetables, including citrus, mangoes, Medjoul dates, pomegranates, grapes, sweet peppers, carrots, lychees, peaches and nectarines. Galilee’s avocado fields are located in Israel’s Galilee region in the north of the county. The regional climate provides a nine-month growing season, from September to May, and contributes to a range of varieties of avocado, each with different taste and quality characteristics. Treatment on the commercial line will begin at Galilees’ packing houses and is expected to run throughout the 2021/22 growing season. “We are pleased that Galilee has decided to launch a commercial application of Save Foods’ products,” says Dan Sztybel, CEO of Save Foods. “Galilee has one of the most advanced operations in the industry. I am confident that our treatments will continue to deliver the benefits they expe-

GROENTE & VRUGTE | NOVEMBER • DESEMBER 2021

rienced in the smaller avocado pilots on a larger scale and ensure they safely export high-quality avocado with a better shelf life while complying with the strict regulations and protocols. Instituted by their EU customer base.” Dror Eigerman, CEO of Galilee Export and member of the company’s advisory board, commented saying, “We have the highest quality standards in the industry to ensure that we provide our customers with excellent produce that not only complies with all regulatory demands but also remains fresh and delicious on the shelves. My experience with Save Foods, as both a customer and an advisor, has been exceptional, which gave me the confidence to initiate the commercial run on our most important produce harvest.” Sztybel concluded, “It often takes a few growing seasons to prove our products, especially with larger companies, but over that time, we also establish a solid working relationship with them and earn their trust. Galilee is one of the leading companies in the industry, and I expect that a successful commercial test will lead to the treatment of their other many produce lines going forward.”

SUBTROPICAL FRUIT

Dr Frikkie Maré, Senior Lecturer in the Department of Agricultural Economics at the University of the Free State (UFS)

Relief to farmers in need A new non-profit organisation established by a number of businesses focus on helping individual agricultural producers in need.

he agricultural sector is used to facing events of abnormal impact, including floods, droughts, veld fires and disease outbreaks. Even if it is possible to prepare against any of these risks by taking proper measures, for instance, by having a farm emergency plan in place or by securing property proper ly, there are times when it is not possible or practical for the modern-day South African farmer to manage all the risks they are facing proactively. In times like these, the newly established non-profit organisation, the Agri Relief Foundation (ARF), provides an invaluable service to the agricultural sector. This initiative is the brainchild of a number of businesses in the agricultural sector. Dr Frikkie Maré, Senior Lecturer in the Department of Agricultural Economics at the University of the Free State (UFS), is one of the directors of the organisation, which focuses on assisting agricultural producers in need. Although there are many institutions in South Africa assisting farmers, most of the current initiatives are geared towards large-scale disasters, such as severe droughts, floods, unpreventable pests, diseases and veld fires that affect many producers. According to Dr Maré, the ARF will focus on helping indivi dual agricultural producers in need, both financially and other wise. This may include elements such as the loss of grazing due to brown locusts, assistance after a farm attack or murder to ensure the day-to-day running of the farm, and localised

natural disasters such as floods, hail, severe cold or fire. The group of directors plays a key role in screening the applications for assistance and deciding who they can assist based on merit and the availability of resources. Besides the direct benefit to the farmer, this initiative also adds value to the wider society. “When the sustainability of an agricultural producer is under threat, it also threatens the livelihoods of his/her workers and their families, the rural economy of the nearest town where they purchase production inputs and general groceries, as well as society at large, as less food and/or fibre will be produced,” explains Dr Maré. “The assistance of the ARF will therefore ripple out to a much larger level than only the agricultural producer.” There is also a benefit for the university. In the classroom, Dr Maré will be able to share any knowledge he is gaining in this process with his students. “Agricultural economics is fundamentally about ensuring the long-term sustainability of agricultural production through concepts, including but not limited to production economics, natural resource economics, agricultural management and marketing. My involvement in the ARF will provide examples of what can go wrong in terms of primary production that threatens the sustainability of the enterprise and what can be done to assist,” he says.

VEGETABLES & FRUIT | NOVEMBER • DECEMBER 2021

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SUBTROPICAL FRUIT

The world of avocados As a leading producer and exporter, South Africa expects an uptick in avocado exports this season, mainly due to momentum in the world economy. Global production and demand influence the local industry. The healthy nature and multiple uses of avocados result in strong consumer demand for avocados.

outh Africa is a leading producer and exporter of avocados. In addition, South Africa supplies avocados to many global markets across the world. Over the last five years, the South African avocado sector harvested approximately 125 000 tons of avocados per annum. The area under commercial avocado orchards stands around 14 700 hectares, with new plantings of about 900 hectares added per annum. The avocado sector contributes to at least 11 500 jobs on farms and packhouses. South Africa expects an uptick in avocado exports this season of 66 000 tons compared to 60 000 tons in the previous season. During the past year, there has been a lot happening globally that influenced the industry in South Africa. According to a recent report by the US Department of Agriculture (USDA), Mexican avocado production for the marketing year 2021/22

is forecasted to be 8% lower than the previous marketing year's record production. While production will remain strong, growers expect trees will need to recover for a season. In addition, high international demand and attractive global prices have encouraged producers to export products for higher returns. And while Michoacán is the only state with phytosanitary certification to export to the United States, exports to other global markets are expected to increase in the coming years. According to the USDA’s report, Mexico is the largest avocado producer in the world, accounting for 30% of global production. Planted area is steadily increasing year over year, at an annual growth rate of 3%, mainly due to high profitTO PAGE 14

VEGETABLES & FRUIT | NOVEMBER • DECEMBER 2021

SUBTROPICAL FRUIT

The world of avocados FROM PAGE 12

ability and increased international demand. Mexico produces three varieties of avocado, with Hass accounting for 97% of total production and Criollo and Fuerte accounting for the remaining 3%. The global avocado market is poised to register optimistic growth rates throughout 2021 and 2022 as positive momentum builds in the world economy, though some differences remain among geographies. The pace of change will accelerate in the avocado industry, and companies quickly re-aligning their strategies will emerge stronger from the unprecedented changes. However, the COVID-19 pandemic remains a major threat for most avocado market outlook in addition to concerns of inflation, supply-chain disruptions and weak consumer demand. The growing of avocado in Peru takes place on the country’s coast, with La Libertad being the main producing region. However, in an organised and sustainable manner, international supply has been incorporated with high-quality avocado in regions in the centre and south of the country. According to the Peruvian Hass Avocado Producers Association (ProHass), Peru expects to export 473 000 tons of Hass avocado in the 2021 season, representing an increase of 29,2% compared to

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the 366 000 tons shipped the previous season, as reported by Gestion. Avocado was the main product of non-traditional Peruvian agro-export supplies in the first half of 2021. In 2020, the Netherlands was the main destination for Peruvian shipments, followed by the USA and Spain. The recent Spanish avocado season showed an increase of around 20% this year thanks to good growing conditions. According to the ministry of foreign affairs in the Netherlands, there is still much room for growth. They state that the supply of avocados is increasing fast, but the European market still has room for growth and can absorb the higher volumes. The healthy nature and multiple uses of avocados result in strong consumer demand for avocados. Fruit businesses can free-ride on the promotion of avocados, but to join the success in trade, the supply must be consistent and of high quality. According to them, compared to other high-demand regions, European consumption is still underdeveloped. The average consumption in Europe is 1,16 kg per capita. In the United States, this is 3,5 kg and in Canada, 2,5 kg. Mexico even consumes 6,5 -7 kg per capita. The consumption of avocados in Europe has grown on average by 8% in the years 2017-2019, and the consumption in 2019-20 was 73% higher compared to 2015-2016. Scandinavia has the highest consumption rate per capita, but the recent growth is most notable in countries where consumption is still relatively low, such as Germany, Italy and Eastern Europe. The differences in consumption within Europe and the gap with developed consumer countries such as the United States and Canada, show that there is much potential for growth. However, market maturity could be reached within five to eight years, and consumption will become more stable with current growth rates. According to the World Avocado Organisation (WAO), the avocado consumption in Europe can reach the same level as in the United States in the next eight years. European countries that are currently showing the biggest increase in consumption is France and the United Kingdom. They are the leading end markets for avocados, while Scandinavian countries have the highest consumption per capita. Although the growth in these leading consuming countries is slowing down, Germany, Italy and Eastern European countries still have lots of potential in the coming years. According to the African research bulletin, Kenya farmers are switching coffee and tea for avocados to profit from increasing European demand. Farmers are paid the equivalent of just over 10 euro cents per fruit. In European supermarkets, they easily fetch ten times that amount, if not more. Kenya’s temperate climate is well-suited to avocado cultivation, especially around the high-altitude town of Thika, north of Nairobi. Avocados account for more than 9% of agricultural exports. The strong demand from European countries allows companies like Kimutai’s to export throughout the year. This all results in a lot of opportunities for South African producers.

VEGETABLES & FRUIT

NOV • DEC 2021

SUBTROPIESE VRUGTE

We are not alone

– The soil, microbes and human health Ian Glass LOWVELD SUGARS

The good earth

healthy, diverse microbe population in our environment and within each of us is essential for our own health and future survival. In 1937 Franklin D Roosevelt, President of the United States of America during some of its darkest days of a crippling economic depression coupled with soil degradation that led to the “Dust Bowl” phenomenon, wrote that “The nation that destroys its soil destroys itself.” These words were a stark reminder that the literal fabric of society and our very existence on this planet is facilitated by the ability of our soils to produce food for our survival. With advancements in scientific observation and understanding, more and more investigation is underway into examining the correlation between the health of these life-giving soils and our own health and well-being. The connection between soil and human health has long been recognised, if not well understood. In 500BC, Hippocrates of Cos, the father of modern medicine, wrote: “When a physician comes to a district previously unknown to him, he should consider ... the soil; whether it be bare and waterless or thickly covered with vegetation and well watered; whether in a hollow and stifling, or exposed and cold.” Likewise, we have recorded in the book of Numbers, chapter 13: “When Moses sent them to explore Canaan, he said, ‘See what the land is like and whether the people who live there are strong or weak, few or many. What kind of land do they live in? Is it good or bad? How is the soil? Is it fertile or poor? Are there trees in it or not? Do your best to bring back some of the fruit of the land.’” Ninety-five percent of all life on earth lives in the soil, however as Leonardo Da Vinci observed: “We know more about the

GROENTE & VRUGTE | NOVEMBER • DESEMBER 2021

movement of celestial bodies than about the soil underfoot.” The concept of “the good earth” has long been part of the human psyche. Given that almost all of the calories that humans consume come from food produced via the soil, the symbiotic relationship between fertile soil and human life is profound. However, as science began discovering microbes, their presence in the soil and the link of some (like tetanus) to human disease and infection helped create an attitude that the soil is a dangerous place and that things in the soil are trying to kill us. This has influenced our attitudes as to how we treat this invaluable resource. It is estimated that approximately 10 million hectares are lost annually to erosion or increased salinity, while another 20 million hectares are abandoned annually due to decrease in fertility levels. Our overuse of tillage, pesticides and fertiliser has had a huge impact on the microbial and fungal life of soil. Dead soil is more prone to erosion and water logging. Water logged soils in turn are more hospitable to anaerobic bacteria, many of which are plant pathogens. The depletion of microbes that are able to scavenge and hold nutrients has led to the need for higher artificial fertiliser inputs and greater environmental pollution. Nitrate run-off contaminating water resources, residual chemical pollutants taken up by crops leads to human and animal consumption of toxins. Toxins include heavy metals like lead and arsenic. Both of these occur naturally in the environment, but the effects of microbes and other minerals in healthy soils form bonds that render them less or non-toxic. Nitrification from excess fertiliser, however, leaches lead out of these bonds. Arsenic is a component of common herbicides and is a contributor to many cancers and other diseases. These and other pollutants can cause a large array of health issues. The concentrations do not need to be high in the soil but the accumulative effects can lead to toxic levels in animals and humans. TO PAGE 16

SUBTROPICAL FRUIT

The soil, microbes and human health FROM PAGE 15

Soil microbes in plant and human health The microbe world that inhabits healthy soil and plants is startlingly similar to the human digestive system. In both systems, bacteria and fungi help digest nutrients, break down toxins and ward off attacks as well as a host of other functions still being discovered. What we consume has a very marked effect on the microbes that inhabit us. Research is showing that microbes present in crops transfer into our own digestive systems, making it more complex and adapting it in accordance with our type of diet. Poor diets, particularly those low in fibre, and negative changes in our guts have serious implications for our overall health, contributing to inflammation, immune diseases, diabetes and obesity among many others. In the same way, the types of plants in a field will dictate the types of microbes present in the soil, as some are more particular to a certain plant type. Soil microbes are a key factor in determining the nutrient content of our food. Taste is an indicator of nutrient density. Microbes make nutrients more readily available to plants as well as boosting the plant’s immunity and assisting in combatting pathogenic attack. Humans require 20 amino acids to function. Of these, only 11 are manufactured in the body. The remaining 9 as well as all 13 essential vitamins come from plant or animal sources. Some of these, like Vitamin B12, are only produced via the action of microbes. In addition, microbes also produce an array of natural products that act as antibiotics and anti-inflammatories. Many of our commercial pharmaceutics are synthetic versions of these products.

Impact of farming activities We are in a degenerative downward spiral. Pesticides and remedies are often as toxic to beneficial microbes as they are to their target. The more chemicals we use to produce crops, the more we damage the soils and organisms required for production, forcing a greater use of chemicals for a successful crop. Increasingly, toxins find their way into our food, poisoning us too in the process. This is a sure path to a bankrupt farming future and impoverished human health. • Our modern monoculture model is a concern. A variety of microorganisms working in harmony will provide the greatest benefit to the plant. However, a single plant species does not provide the necessary environment for the stimulation of a variety of microbes. • The use of harsh toxins is also detrimental to a healthy microbial population. • Leaving the soil bare removes any reason for microbe development and allows for increased soil degradation and desertification. • Overworking the soil is particularly detrimental to microbes. Tillage breaks up the fungal networks, exposes microbes to harmful UV light, damages the soil structure built by microbes and accelerates erosion.

Restorative steps • Holistic decision-making needs to take into account the whole farm and human environment. Nature operates as a whole. Too often, we make knee jerk reactions. There is a pest, kill it. Rather than questioning what may have prompted this pest’s emergence and what are the long-term consequences of our interventions. • The inclusion of animal herds into the farming system if possible is extremely beneficial. They process the cover crop and inoculate the soil with microbe rich manure. • Building organic matter in the soil as much as possible. Slash or roller crimp the cover crop in time to allow breakdown before light tillage incorporation. Never burn the cover crop. This deprives the soil of the nutrients taken up to produce the cover crop while releasing all of the carbon into the atmosphere. • The less tillage of the soil, the better. This seems particularly difficult in industrial agriculture but is an important factor in improving soil life. Ploughing is particularly destructive. Remember, nature does not like bare soil. • A mix of plant types provides the most benefit. Encourage cover crops in orchards. Mix plantings or crop rotations of a variety of crops or cover crops, even natural grasses or other fodder crops. Fodder crops can then be used as grazing or baled and sold. • Wise choice in the selection of fertiliser products. Not all chemical fertilisers are equal. High chlorine based fertilisers such as potassium chloride will act as a sterilant to soil microbes. The chelation of fertiliser with humic or fulvic acid will make it less harmful to soil microbes and more effective. Our soils already contain microbe populations in varying ratios. Making the environment more hospitable will allow them to multiply and find their balance. The objective is a healthy mix of the myriad of organisms that make soil healthy. Inoculating the soil with small amounts of high quality compost can encourage the entire microbiome to flourish. This will go a long way to stimulate healthy crops to feed healthy humans. For instructions on making your own bio-reactor compost and its use, visit: https://www.csuchico.edu/regenerativeagriculture/bioreactor/ bioreactor-instructions.shtml

References

BEHAR, M. 2020. Soil health means better human health. Successful Farming. Published 7/15/2020. https://www.agriculture.com/crops/soil-health/ soil-health-means-better-human-health BREVIK, E.C., SLAUGHTER, L., SINGH, B.R., STEFFAN, J.J., COLLIER, D., BARNHART, P. & PEREIRA, P. 2020. Soil and human health: current status and future needs. Air, Soil and Water Res. 13: 1-23. doi: 10.1177/1178622120934441. STEFFAN, J.J., BREVIK, E.C., BURGESS, L.C. & CERDÀ, A. 2018. The effect of soil on human health: an overview. Eur. J. Soil Sci. 69(1): 159-171. doi:10.1111/ejss.12451.

VEGETABLES & FRUIT | NOVEMBER • DECEMBER 2021

SUBTROPICAL FRUIT

New study reveals ethephon’s role in regulating dormancy and flowering in litchi The Agricultural Research Council-Tropical and Subtropical Crops campus conducted research on optimising ethephon applications to completely inhibit any new shoot growth as opposed to frequent spot sprays for control of young flush, which are commonly used in the industry. Regina Cronje1, Elliosha Hajari1, Innocent Ratlapane1 and Arnold Jonker2 AGRICULTURAL RESEARCH COUNCIL-TROPICAL AND SUBTROPICAL CROPS 2 UNIVERSITY OF LIMPOPO 1

uccessful flower induction and initiation in litchi are highly dependent on low temperatures (Figure 1). Litchi flower induction takes place in dormant buds of mature shoots and requires minimum temperatures below 15 °C. At flower initiation, the so-called while millet stage, temperature will determine whether a flower panicle will be pure, i.e. without leaves, or leafy (generally less fruitful). Shoot maturity is an essential prerequisite for flower induction in litchi and any new vegetative growth will reduce flowering.

Traditionally, the plant growth regulator, ethephon, has been used in South Africa for spot spray applications to chemically remove such unwanted shoots. However, in the past decade, warmer winters have caused persistent vegetative shoot growth, which made the frequent use of spot spray applications less efficient and economical. In addition, inconsistent inductive temperatures have caused concurrent flower emergence, making growers hesitant to use ethephon out of concern that its application could damage already developing flower panicles. This necessitated a new approach to chemical flush control using ethephon. Therefore, scientists at the Agricultural Research Council-Tropical and Subtropical Crops campus conducted research on optimising ethephon applications to completely inhibit any new shoot growth prior to, and during, the flower induction period as opposed to frequent

VEGETABLES & FRUIT | NOVEMBER • DECEMBER 2021

SUBTROPIESE VRUGTE

Figure 1. Developmental stages in litchi flowering (according to the BBCH scale, Wei et al., 2013).

spot sprays for control of young flush, which are commonly used in the industry. This research has shown that ethephon applied as a full canopy spray when the last desired postharvest flush has hardened off (late March and April), can inhibit new flush growth for up to six weeks depending on the ethephon concentration and prevailing temperatures after application. The full canopy treatment also delayed flower panicle emergence to a time where temperatures were consistently low enough for successful flower induction and increased flowering and yield without delaying harvest. Based on these results, a further study was initiated to investigate the mode-of-action of ethylene, the breakdown product of ethephon, by determining ethylene release and gene expression of various dormancy- and flowering-related genes in leaves and buds.

Effect of ethephon on ethylene release and gene expression Measurements of ethylene gas released by leaves and buds before and after ethephon application at 1000 parts per mil-

Source: Zhang et al. (2014).

lion (ppm) revealed that immediately after application, a burst of ethylene was released in both leaves and buds. However, while ethylene release in the leaves immediately dropped, ethylene release in buds remained high for about seven days and thereafter declined at a slow rate, only reaching the same level as the untreated buds after more than four weeks (Figure 2). Ethephon treatment thus delayed bud break by about three weeks (as indicated in Figure 2). These results confirmed that ethephon application is directly responsible for inhibiting bud growth. In addition, ethephon application was able to maintain bud dormancy during a period of high temperatures at the end of May (around Day 42 after application) (Figure 2). In order to investigate the effect of ethephon/ethylene at a molecular level, gene expression analyses were performed using real-time quantitative polymerase chain reaction (RT-qPCR). The genes studied in this context were, among others, the ethylene pathway gene LcEIN3, the flowering suppressor gene LcFLC, and the flower promoter gene LcFT2. Ethephon treatment did not have any effect on LcEIN3 exTO PAGE 20 Figure 2. Ethylene release before and after ethephon application in leaves and buds of untreated (control) and treated trees and average daily temperatures during the observation period. Time of bud break and white millet stage for both treatments are indicated.

GROENTE & VRUGTE | NOVEMBER • DESEMBER 2021

SUBTROPICAL FRUIT

New study reveals ethephon’s role in regulating dormancy and flowering in litchi FROM PAGE 19

pression in leaves (data not shown), but significantly increased LcEIN3 expression in buds one day after application and during mid dormancy (Figure 3A). This confirmed the trends seen in the ethylene release data and demonstrated that the target sites for ethephon are the buds. Likewise, ethephon application significantly increased expression of the flowering suppressor gene LcFLC in the buds (Figure 3B). Therefore, ethephon treatment had a direct effect on these genes and directly influenced tree phenology, i.e. by causing extended bud dormancy and preventing vegetative growth prior to flowering. The prolonged dormancy subsequently allowed bud break to occur at a period with lower temperatures, compared with bud break in untreated trees, which provided a stronger stimulus for the significant upregulation of the flower promoter gene LcFT2 at bud break (Figure 3C), leading to successful flowering with significantly reduced leafy panicles compared with the control treatment. This study is the first of its kind in South Africa revealing the direct involvement of ethephon/ethylene in the physiological and molecular regulation of dormancy and flowering of litchi. Furthermore, it showed that full canopy ethephon applications can be used to mitigate the adverse effects of seasonal climate changes.

Future application of gene expression information in horticulture The application of gene expression studies is becoming more and more relevant and available for practical agriculture. Traditionally, the appearance of phenotypic traits has been used as an indication of certain growth conditions. However, phenotype lags behind gene expression, as seen in the above study, and does not reflect the real time developmental and metabolic status of the plant. Gene expression information can therefore be useful for monitoring and diagnosing specific developmental conditions at the gene level to predict unfavourable change before it happens, thereby allowing timely action to be taken. Such information also provides guidelines for more efficient and cost effective orchard management to improve productivity and quality of horticultural products.

Figure 3. Gene expression levels of the ethylene pathway gene LcEIN3 (in buds; A), the flower suppressor gene LcFLC (in buds; B) and the flower promoter gene LcFT2 (in leaves; C) in untreated (control) and treated trees.

E-mail: regina@arc.agric.za

References

Wei, Y.Z., Zhang, H.N., Li, W.C., Wang, J.H., Liu, L.Q. and Shi, S.Y. 2013. Phenological growth stages of lychee (Litchi chinensis Sonn.) using the extended BBCH-scale, Sci. Hort. 161: 273-277. Zhang, H.N., Wei, Y.Z., Shen, J.Y., Lai, B., Huang, X.M., Ding, F., Su, Z.X. and Chen, H.B. 2014. Transcriptomic analysis of floral initiation in litchi (Litchi chinensis Sonn.) based on de novo RNA sequencing. Plant Cell Rep. 33(10): 1723-35.

VEGETABLES & FRUIT | NOVEMBER • DECEMBER 2021

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SUBTROPICAL FRUIT

Plant nutrition concepts in nut crops Although nut crops are often grouped together as a group of unrelated crops, there are certain nutrient strategies that apply to all which can be optimized by using Ultrasol K Plus** (Potassium Nitrate).

ut trees are normally low yielding high-value crops, and good nutritional management practices are necessary to ensure optimum yield and quality. Besides important physical soil factors, such as soil compaction, soil drainage, effective rooting depth and soil temperature, important chemical aspects to consider are soil pH, salinity, fertiliser timing and placement, nitrogen form and the nutrient removal amounts (the quantity to apply). Nut crops are mostly a group of unrelated crops. Generally, they are grouped together because the fruit type is a nut and harvesting, post-harvest processing, nutritional value and marketing are relatively similar. To generalise with nutrient strategies for the different nut types would be an error, so it is best to focus on a few factors that would be common to most nut types. Most nut trees are sensitive to chloride. Although chloride is an essential element in trace amounts, excess chloride, either already in the soil or in the irrigation water, or applied as KCL fertiliser to supply the tree with potassium (K), will cause a reduction in yield and quality. Toxic amounts of chloride will result in leaf scorch and will reduce photosynthetic capacity. In addition, there is a negative linear relationship between chloride uptake and reduced nitrate-nitrogen uptake. Chloride, therefore, even in sub-toxic amounts but in excess, will inhibit nitrate-nitrogen uptake affecting plant growth, resulting in reduced yield and quality. Most nut trees are susceptible to salinity. Naturally occurring excesses of chloride are often associated with excessive sodium, the two main elemental ions causing salinity stress. Salinity stress, or salt accumulation in the root zone, will occur in drier regions and/or with insufficient irrigation water to leach out any accumulated salts. It is imperative in situations such as this to select fertilisers with the lowest salt index. Because nitrogen and potassium are both elements used in the

greatest quantities by horticultural crops – including nuts – it makes perfect sense to use potassium nitrate as the fertiliser of choice to supply both these “high requirement” elements. Salinity is not only caused by excess chloride and sodium. Excesses of calcium and magnesium, generally associated with high pH soils, will also cause salinity. In addition, any element given in abundance to the requirement by the plant also contributes to root zone salinity which will compound any natural salt salinity that there is. A good example of this might be an over-application of sulphates. Sulphur is certainly an essential element, but it is needed in relatively small amounts. Often growers will go chloride-free (on good advice) and then apply the large K requirement as potassium sulphate. The excess sulphate (up to 10x more than what is required) contributes directly to soil salinity, affecting both yield and quality. The figure shows the relative salt index or % electrical conductivity (% EC) compared to potassium nitrate as the standard (100%). The shown fertiliser types are adding salts in excess of what is required by the plant, contributing to the EC stress (salinity stress). At the same amount of N and K, using potassium sulphate or potassium chloride in conjunction with another N source greatly increases the root zone salinity. Besides supplying both essential elements, potassium nitrate supplies nitrogen in the nitrate (NO3)- form. As can be seen from the chemical formula, this is a negative anion. Plants like to maintain an electrochemical balance and (NO3)synergistically enhances the uptake of K+, Ca++ and Mg++, the positively charged cations. Therefore, it makes perfect sense to supply the high nitrogen requirement and the high potassium and relatively high calcium and magnesium requirements using nitrate nitrogen. Potassium nitrate enables producers to maximise their nitrate inputs facilitating this uptake synergy. For high pH areas, acid-enhanced potassium nitrate is available as Ultrasol K Plus Acid***. *All claims in this article can be substantiated with references which can be made available on request. **Reg No K5020 Act 36/1947. Registration holder Sociedad Quimica y Minera (Africa)(Pty)Ltd ***Reg No K6489 Act 36/1947. Registration holder Sociedad Quimica y Minera (Africa)(Pty)Ltd Disclaimer The information herein contained is given to the best of SQM’s knowledge and is believed to be accurate. The conditions of use and application of the suggested recommendations, are beyond SQM’s control. No warranty is made as to the accuracy of any data or statements contained herein. SQM specifically disclaims any responsibility or liability relating to the use of the recommendations and shall under no circumstances whatsoever, be liable for any special, incidental or consequential damages arising from such use.

VEGETABLES & FRUIT | NOVEMBER • DECEMBER 2021

SUBTROPICAL FRUIT

Will dragon fruit take over as superfruit? Even though the South African dragon fruit industry is relatively young, the fruit as we know it today has been produced commercially since 1990 in Vietnam, Malaysia, Thailand, Taiwan, Sri Lanka, China, Israel, California and Central America.

rown in tropical and subtropical regions of the world, the plantings of dragon fruit are increasing in South Africa, where producers are fast establishing a growing export industry. Pioneers in South Africa’s dragon fruit sector recently established the Southern Africa Dragon Fruit Association. PMA South Africa’s live broadcast in partnership with Beanstalk Global recently, brought together a panel of experts who discussed the potential of the dragon fruit industry in South Africa. On the panel was Michael Muller from the Muller Familie Boerdery Trust, Fred Steyn - newly appointed Chair of the Southern Africa Dragon Fruit Association, CT van der Merwe from CEO of AL3 Boerdery, Laura Strever from Amorentia Estate and Nursery, and Jason Sampson from the Department of Plant and Soil Sciences at the University of Pretoria. Amorentia Nursery, based in Tzaneen, Limpopo, is just one of the nurseries making the new sweet cultivars available. Strever said Amorentia Nursery started propagating dragon fruit under the trademarked name Amorentia Sweet Dragon Fruit after they caught a glimpse of the potential of the new tasty varieties. She described the fruit as exotic, vibrant, exciting and enticing. Moreover, it is versatile – eat it fresh, drink it juiced and use it in more complex recipes with other products. “These features make dragon fruit marketable and con-

sumers have already started adding it to their shopping baskets. Not so long ago, one did not find people putting blueberries in their shopping baskets. With the way it was marketed, blueberries became a staple food for many people,” said Strever. Van der Merwe and Sampson agreed that dragon fruit could become one of the most popular fruits worldwide if one has the right influencers and educate consumers on the health benefits of this super fruit. The fruit is harvested from around December/January until April/May and provides a huge export potential to European and US markets during their off-seasons. The cold chain is vital in delivering good quality fruit to consumers, especially for producers who are farming far away from marketing facilities. “At this stage, most of the dragon fruit worldwide are exported by ship, while South Africa can export by airfreight to reach markets in a much shorter time. With efficient packhouse operations, the fruit could be harvested and delivered to global markets within a week,” said Steyn. According to Muller, dragon fruit production is a manual, labour-intensive industry, creating much-needed employment in South Africa.

VEGETABLES & FRUIT | NOVEMBER • DECEMBER 2021

NETTE

Verbouing van gewasse in hidroponiese stelsels Die verbouing van gewasse in hidroponiese stelsels is nie ‘n nuwe tendens in Suid-Afrika of die res van die wêreld nie. Dit het oorspronklik ontwikkel tydens die antieke wêreld en het deur die jare tot verskeie vorms en stelsels ontwikkel, met een deurlopende kenmerk – die plante binne die stelsel word deur ‘n wateroplossing van voedingselemente gevoed en groei altyd in ‘n medium of daarsonder.

idroponiese stelsels kom in alle gevalle onder besker ming voor, hetsy onder skadunette of plastiekstrukture. Die verbouing van groente in hierdie stelsels hou verskeie voordele in omdat elke aspek van die plant se groei, bestuur kan word. Dit maak egter die verbouing uiters arbeidsintensief en goeie deurlopende bestuur word vereis. Groentegewasse wat in hidroponiese stelsels verbou word, is gewoonlik van hoogstaande gehalte en premie-pryse kan beding word. Omdat die verbouing grootliks beskerm word, kan die omgewing se uitwerking beperk word en is die plante oor die algemeen nie so blootgestel aan stremming nie. Dit kan ook aanleiding gee tot ‘n verlenging van die produksieseisoen. Die insetkoste van beskermde produksie is hoër as by ooplandproduksie en daarom word produksieteikens gestel, wat deurlopend behaal moet word. Produsente wat hulle gewasse onder beskerming kweek, poog om die opbrengs per oppervlak tot ‘n maksimum te verhoog, eerder as om op groter oppervlaktes te plant. Met die skerp styging in insetkoste kan hierdie praktyke ook in die oopland toegepas word. Indien die produsent op dieselfde oppervlak met dieselfde insetkoste hoër opbrengste kan behaal, maak dit die onderneming winsgewender. Verskillende strukture en stelsels kan vir verbouing onder beskerming gebruik word en dit is raadsaam om eers deeglike navorsing te doen voordat op ‘n spesifieke stelsels besluit word. Aspekte wat in ag geneem moet word sluit in die soort gewas, die ligging en klimaat van die gebied. Strukture wat in een gebied doeltreffend is, het nie noodwendig dieselfde resultate in ‘n ander gebied nie. Die ontwerp van ‘n plastiektonnel is byvoorbeeld baie belangrik ten opsigte van ventilasie. Indien ventilasie onvol doende is kan dit onproduktiewe plante tot gevolg hê, asook ‘n temperatuurverhoging wat tot ver bo die optimale tempe ratuur van die gewas kan gaan. Balans is baie belangrik, veral indien die produsieseisoen verleng wil word. Produsente wil graag hitte behou, veral in die koeler tye, en gevolglik word minder ventilasie toegepas. Dit kan lei tot verlaagde CO2 vlakke, hoër relatiewe humiditeit en selfs die uitbreek van verskeie siektes, wat groot verliese tot gevolg kan hê. Die soort plastiek of skadunet wat vir die struktuur gebruik gaan word moet die gewas wat geplant gaan word in ag neem. Rissies kan byvoorbeeld in hoër persentasie skadu groei as tamaties. Rissies onder hoër skadu-persentasie neig

GROENTE & VRUGTE | NOVEMBER • DESEMBER 2021

Basiese nethuisstruktuur.

om groter blare te maak om lig te onderskep, terwyl tamaties geneig is om hulle internodes te rek en dus te vinnig groei, wat meer oplei en arbeid vereis. Indien die produsent verskeie gewasse onder een struktuur wil verbou, moet ‘n goue middeweg gevind word. Die gebruik van skuifbare nette of skerms raak gewilder en dit kan die uitstraling op baie warm dae verminder en in meer bewolkte dae geskuif word. Die koste-implikasies is wel groot, maar vir die produsent wat sy kosteberekening en potensiële inkomste bereken kan dit die moeite werd wees. Soos genoem het elke gewas sy eie optimale omstandighede om ‘n maksimum opbrengs te lewer. Die klimaat binne die struktuur moet so goed as moontlik beheer word om die stremming op die gewas tot ‘n minimum te beperk. Met die verbetering van tegnologie kan al hoe meer faktore binne die strukture beheer word. Al hierdie beheermaatreëls kom egter teen ‘n prys – dit is raadsaam om dus eers elke voordelige effek teenoor die koste op te weeg. Indien die gewasse reg bestuur word kan ‘n eenvoudiger nethuisstruktuur winsgewender wees as ‘n plastiektonnel. Die stelling “gee die plant wat hy nodig het, wanneer hy dit nodig het”, klink dalk eenvoudig, maar dit is hierdie stelling NA BLADSY 26

NETS

Verbouing van gewasse in hidroponiese stelsels VANAF BLADSY 25

wat ‘n produsent se sukses bepaal. Aanpassings en verstel lings moet voortdurend beplan en bestuur word en dit kom gewoonlik met ervaring van die plaaslike omgewing. Daar is soveel van hierdie strukture wat langs die paaie sigbaar is, waar die stukkende plastiek in die wind wapper en die strukture nutteloos staan – ‘n totale verkwisting van goeie geld. Talle kundige mense in die bedryf kan help met die bestuur van plante onder beskerming en meer as genoeg literatuur is beskikbaar om soveel as moontlik van die bestuur en balans van ‘n plant te verstaan. Omdat gepoog word om die plant optimaal te bestuur, is dit egter ook waar dat baie insekte en siektes onder die ideale omstandighede sal floreer. Deeglike kennis van al die moontlike peste en siektes wat kan ontstaan is van uiterste belang – ook hier is verskeie hulpmiddels wat geraadpleeg kan word. Let ook op vir werksgroepe op sosiale media wat deur produsente geskep is, waar hulle mekaar ondersteun deur te kommunikeer, foto’s te deel, vrae te vra en raad te verskaf – alles ten doel om produksie te optimaliseer. Die gebruik van opgeleide arbeid vir daaglikse waarnemings op moontlike siektes of insekte, is van die uiterste belang en kan keer dat groot skade gely word deur té laat op ‘n potensiële probleem te reageer.

Die soort gewas of produk wat onder beskerming geproduseer word, is oor die algemeen gewasse met hoër waarde, soos gekleurde soetrissies en spesialiteitstamaties. Ander gewasse soos slaai en rankboontjies kan suksesvol onder beskerming verbou word, veral in tye van die jaar wanneer produksie in ooplande beperk is. Sommige gewasse se produksiesiklus is baie vinniger as ander en verskeie oeste kan binne ‘n jaar geproduseer word. Om vir die produsent ‘n verskeidenheid gewasse te bied om te verbou, is saadmaatskappye voordurend besig om nuwe ontwikkelings vry te stel. Sakata het oor die afgelope jaar verskeie nuwe produkte die lig laat sien, met onder meer spesialiteitstamaties, soetrissies en komkommers. Hierdie reekse is besig om baie gewild te raak en is nie altyd geskik vir ooplandproduskie nie. Dit skep nuwe geleenthede vir produsente om verskeie produkte te bemark. Vir meer inligting oor Sakata se nuwe reeks produkte, skakel gerus die streekverteenwoordiger of besoek die maatskappy se webwerf by www.sakata.co.za vir meer inligting. VRYWARING: Hierdie inligting is op Sakata se waarnemings en/of inligting vanaf ander bronne gebaseer. Aangesien gewasprestasie bepaal word deur die interaksie tussen die genetiese saadpotensiaal, die fisiologiese eienskappe daarvan en die omgewing, insluitend bestuurspraktyke, gee Sakata geen uitdruklike of geïmpliseerde waarborg vir die prestasie van gewasse in verhouding tot die gegewe inligting. Sakata aanvaar nie aanspreeklikheid vir enige verlies wat mag ontstaan nie, direk of as gevolg daarvan. Lees asseblief eers Sakata Seed Southern Africa (Pty) Ltd se verkoopsvoorwaardes voordat saad bestel word.

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NETS

Shade netting

makes the difference

The choice of the colour and density of the net should be taken into account when erecting the shade net structure.

The demand for shade netting in the agricultural sector increases because it can reduce the risk that severe climate poses to the producer. Research indicates that shade netting provides the necessary protection for crops from extreme climatic conditions and reduce their adverse effects.

hade nets have been found to increase the quality of crops. Water-saving is another benefit of using nets, because it reduces the amount of evaporation. This also means less damage to crops by sunburn, insects and birds. The increased crop quality is largely due to the optimal growth environment created within the shade net structure. A well-built structure, with the correct density and colour shade net, creates a protected microclimate that is ideal for growing seedlings, cut flowers and potted plants, and growing vegetables and fruits. Deon Joubert, managing director of Multiknit, says that although their product carries a 10-year warranty against UV degradation, they have had nets up in excess of 20 years. The producer needs to understand that the product degrades gradually over the ten-year period. The product will not have the same protection properties after ten years of exposure to the natural elements as in year one. “We ensure that we utilise the best available UV stabilisers and ensure that the dosage far exceeds the required warranty period. We pride ourselves that we use the best UV stabilisers, HDPE and colour pigments available in the world. We ensure that all products used in the production process are of the utmost quality. The combination of the product we incorporate as well as our lockstitch knitting pattern ensures our quality. “We have been in business since 1964 and the experience

and expertise we have available within our business allows us to develop our exceptional products. For example, the secret of climate control under shade net is determined by the height of the structure”, says Joubert. According to him, the higher the structure, the greater the volume of air under the net. Therefore, the temperature effect the net has depends not only on the height of the structure but also on the density and colour of the net as well. The presence of nets on the perimeter of the net-house slope at a 45-degree angle will affect the free flow of air movement under the structure. The main reason for the net is to protect the crops. Still, the added advantages apart from protection against the sun, hail, birds and larger insects are that by choosing the correct colour and density of shade net, the producer protect and enhance the fruit quality and potential volume of the yield. Furthermore, the presence of a shade net over a crop will directly influence the plant's water consumption. Therefore, the net's colour and density and the presence of side nets are directly related to the potential savings. The choice of the colour and density of the net should be taken into account when erecting the shade net structure. It plays a major role in changing the quality of light transmitted and its different effects on crops. Red nets allow more red light to pass to the plant and, for example, can help extend the stem

VEGETABLES & FRUIT | NOVEMBER • DECEMBER 2021

Each crop or tree has its own unique lighting needs, which are further influenced by management input and production adjustments.

length of roses. On the other hand, more blue light transmitted to the plant can enhance colour development or stimulate root development. The amount of blue and red light and the ratio of blue to red light must be determined by the producer to obtain the best quality, size and colour of fruit and vegetables or improve flower size and stem length of flowers. Each crop or tree has its own unique lighting needs, which are further influenced by management input and production

PROTECTING YOUR

CROPS FROM THE

NETTE

adjustments. It is therefore advisable to approach a Knittex specialist to obtain the appropriate shade net for specific needs. For more information, contact one of the Knittex representatives for more guidance, as shade netting requirements will depend on plant variant, location, soil type and climatic conditions in a region. Tel: 011 692 1658 or visit www.knittex.co.za. All SpectraNet can be supplied standard or stented and comes with a 10 year manufacturer’s warranty against UV degradation.

PACKAGING

Bucking the trend Over the years, bag closing equipment company Buckle Packaging has managed to buck more than one economic downturn, and the COVID-19 pandemic has been no exception. If anything, the business has come out stronger than before, taking on new employees and growing the business in times when many companies globally have had to close their doors permanently.

anaging director Anthony Mason of Buckle Packaging puts this down to his strategy of building client bonds and maintaining high stock holdings. “Buckle Packaging has managed to cement stronger relationships with our clients over the past five years. This has been due to customer service and extensive stock holding, especially during the pandemic. We have managed to maintain the service that our customers are accustomed to, while steadily growing the business,” maintains Mason. The company’s beginnings go back to 1979 when they first opened for trading under the leadership of Anthony’s father, Alan Mason. The business has always focused on supplying the best quality packaging equipment, and today it has become Africa’s largest supplier of industrial bag stitching machines and heat sealing systems. The equipment comes from leading suppliers Fischbein-Saxon. Buckle Packaging also focuses on providing customers with technical maintenance and after-sales service and keeping a division of fully stocked spares. Buckle Packaging keeps up with new trends and makes sure that its customers have the best that modern research and technology can offer. “Fischbein-Saxon continues to develop state of the art packaging equipment,” explains Mason. “On the bag stitching machinery, we have recently launched the Fischbein 100-2 Double Needle bag stitching machine. The machine allows for the bag to be double stitched across the top in one action. This is required by certain industries, mainly within the food sector.” Planning ahead averted the consequences of the global shipping crisis and keeping the company’s profile strong through targeted marketing and a pro-active sales team have been key to Anthony Mason’s efforts of maintaining Buckle Packaging’s position as a top supplier of bag closing equipment.

BUCKLE PACKAGING (PTY) LTD Bag Closing Technology

“We keep the correct decision-makers in the market abreast of what we have to offer. We have a passion for keeping ourselves ahead as the leaders in bag closing technology.”

The new Insectec facility is just outside Letsitele in Limpopo, where both the host and control insects are bred.

ALGEMEEN

Fighting the mealybug Founded in 2015, Insectec, a local company in Limpopo, has expanded from a small laboratory in Tzaneen to becoming a leader in the production of natural enemies for use in integrated pest management systems on farms in South Africa.

n a joint venture, three farming enterprises in the Letsitele area, namely Mahela Group, Komati Fruit Group and Laeveld Citrus, joined forces with Insectec and completed a stateof-the-art Insectary situated in Letsitele. This new insect rearing facility has recently been opened in Letsitele and boasts the latest technology and a local research and development team that enables them to address the specific needs of their clients. Cutting-edge technology has been installed in the new insectary that will allow the company to produce large numbers of healthy, high-quality, beneficial insects for use in agriculture. The new facility will also host a research and development department. “Although we might be a bit cheeky to claim it, we believe that we have the largest insectary in the Southern hemisphere,” says Karel van Heerden, Chief Executive Officer. “Our mission is to produce integrated and sustainable solutions for pest management that contribute to a healthier and more productive agricultural systems. “Investment in innovation is the foundation for sustainable solutions in agriculture. Our business is based on proper research, and the development department is focused on finding new innovative methods and solutions to address pest management problems. In addition, we develop products for local conditions in conjunction with our clients,” he added. The Insectary is run by Hannah Otto, Director and Production Manager, whose expertise in insect breeding under South African conditions is well-known. The facility focuses on the production and application of beneficial organisms used

GROENTE & VRUGTE | NOVEMBER • DESEMBER 2021

in biological pest control and integrated pest management programmes. Insects will be massed-produced to support integrated pest management (IPM) programmes of citrus and grape farmers locally and abroad. The use of natural enemies in most cases is incorporated into the integrated pest management programmes of producers. IPM is a system of managing pests in agricultural crops through a combination of biological, cultural, physical and chemical control methods. IPM is an effective and environmentally sensitive approach to pest management that relies on a combination of commonsense practices, says Andrew Bennett, Agricultural Consultant. “IPM programmes are based on information regarding the life cycles of pests and their interaction with the environment. This information, in combination with available pest control methods, is then used to manage pest damage to crops by the most economical means with the least possible hazard to people and the environment,” Bennet explains. “In order to breed the natural enemies, we have to breed the prey. At this stage, the only prey we breed is mealybug, Hemiptere: Pseudococcidae, an economically important pest. Mealybugs are soft-bodied scale insects and extremely difficult to control chemically. The use of natural enemies is considered as the best alternative means of control,” Otto says. All the natural enemies that are produced at Insectec occur naturally in South Africa and are therefore adapted to most regions in the country. Four natural enemies for mealybug are bred. Each of these TO PAGE 32

GENERAL

Butternuts are produced on contract for Insectec for the sole purpose of breeding mealybugs. These butternuts must be disease-free without traces of chemical pest control products and are washed before used as hosts for breeding mealybugs.

Fighting the mealybug FROM PAGE 31 targets a different life stage of the mealybug and can be used to complement each other to control different mealybug species. Some of the natural enemies, however, are host specific and only target certain mealybug species. “The ladybeetle Crypto-tec, Cryptolaemus montrouzieri, targets all mealybug stages and most mealybug species and is compatible with a wide range of crops. The other predatory beetle that we produce, Neph-tech, Nephus kamburovi, however, is a tiny beetle that only feeds on mealybug eggs and early life stage of the mealybug,” she explains. In addition to the two predatory beetles, they also produce two parasitic wasps, Ana-tec, Anagyrus vladimiri, and Cocci-tec, Coccidoxenoides perminutus. They are used together in situations where the citrus mealybug is the dominant species in the orchard as they complement each other by targeting different life stages of the mealybug. Insectec’s packaging is designed in such a manner to keep the insects safe as well as to make it easy for release into an orchard. Although the packaging for the various products looks similar, each product contains different amounts of insects according to the crop as well as environmental conditions. A typical biological control programme to

manage a light infestation of citrus mealybug in a citrus orchard will entail the simultaneous release of about 1 000 Ana-tec and 15 000 Coccitec wasps per hectare. “Each situation is different, and the dosages are dependent on many factors, such as region, climate, mealybug species, infestation level and life span of the pest at that particular moment,” Otto says. The breeding quantities for each of the natural enemies for a particular season are based on planned releases as well as historical data of releases during past seasons. Weather conditions can also play a role. Normally the predators are not released in the winter months in an area that is known for cold winters, as their growth and activity slowdown in the colder months. The best time of day to release beneficial insects into a cropping system is early in the morning or late afternoon when the temperatures are mild. Different techniques are employed for the various predatory insects. “The effectiveness of using natural enemies to control pests is impossible to ignore and therefore have become an integral part of integrated pest management control programmes throughout the world,” Karel says. Consumers are increasingly demanding more sustainably produced food. Driven by the con-

VEGETABLES & FRUIT

NOV • DEC 2021

ALGEMEEN

Insect monitoring forms an important part of integrated pest management programmes. It is crucial to monitor for pests and identify them accurately so that appropriate control actions can be taken. The use of insect traps is one of the ways to monitor insect prevalence in an orchard.

cept of sustainable agriculture and to minimise the impact they have on the environment, producers are also becoming more conscious of the pest control methods they apply on their farms and are increasingly starting to implement IPM systems on their farms. “Biological pest control forms the cornerstone of our Integrated Pest Management strategy at Mahela and focuses on the long-term prevention and management of pests. We introduced biological pest control in fruit production as part of an integrated pest management strategy to reduce the use and impact of pesticides on the environment and biodiversity,” says Eddie Vorster, Director Citrus production at Mahela Group. In the past farmers producing fruit in monoculture systems heavily relied on chemicals only to produce quality and pest and disease-free fruit. It is widely accepted however, now that, in terms of sustainability, this is not an option. Although fruit producers will still employ chemical control measures, at about 3 to 4 months prior to the harvesting season, they need to find alternative ways to control pests and diseases due to maximum residue level restrictions on chemical usage. This is where the true value of biological pest control in an integrated pest management system, and the role this new facility can play, comes to the fore. “To be a successful grower, one needs to understand the balance nature provides,” says Karlien Grobler, Group Quality Manager at Komati Fruit Group. According to Karlien, the incorporation of biological measures remains a challenge, especially without a continuous supply of beneficial insects. “At Komati, we plan the chemical interventions we apply for thrips, red scale, mealybug, and blackspot timeously and carefully to get the control we require with as little as possible disruption of the natural balance. When the risk period for damage ceases, we will top up our beneficial complex with biological insects supplied by Insectec, to sustain us through the remainder of the season.” “Protecting citrus and other fruit production against attacks from pest insects is an essential part of production management, and this is where Insectec will be able to assist our farmers. Our services are available to all farmers,” says Van Heerden.

GROENTE & VRUGTE

NOV • DES 2021

Continuous monitoring remains the cornerstone of an integrated pest management programme regardless of the season.

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GENERAL

Blotchy mottle symptom of HLB. Source: https://www.latimes.com/food/la-fo-citrus-greening-20190329-story.html.

ARC aids in keeping the yellow dragon at bay in citrus orchards Citrus Huanglongbing, better known as HLB, is currently regarded as the most destructive disease of citrus, having caused the near-collapse of the Florida citrus industry in the US over the last decade. ARC-TSC and collaborators facilitate the broader testing of citrus for HLB, therefore helping guard the citrus industry.

itrus Huanglongbing, or HLB, which was first described from China, gives the appearance of a yellow dragon being draped over citrus trees, due the mottling symptom associated with it. The causal bacterial agent of HLB, ‘Candida-

Citrus greening disease (Laf) yellowing symptom observed on citrus Source: R Roberts. in South Africa.

tus Liberibacter asiaticus’ (Las), and its vector Diaphorina citri, has to date not yet been reported from commercial citrus in South Africa. HLB has, however, been identified from Asia, the Americas, Mauritius, Reunion Island and two African countries, i. e. Ethiopia and Kenya. Despite its absence, a relative of Las, ‘Ca. L. africanus’ (Laf), is no stranger to the South African citrus industry, having been associated with citrus greening disease since the late 1920’s. It is also known that the vector of Laf, Trioze erytreae, is capable of transmitting Las, meaning that Las can spread in South Africa orchards in the absence of D. citri. As the symptoms caused by both are similar, it is important that these two be distinguished rapidly by molecular technologies, to ensure that should HLB enter the country, relevant steps can be taken to limit its spread. ARC-TSC, in collaboration with the Department of Agriculture, Land Reform & Rural Development (DALRRD) and Citrus Research International (CRI), are geared towards testing citrus samples for HLB and distinguishing Las from Laf. This partnership will facilitate the broader testing of citrus for HLB, therefore helping guard the citrus industry from HLB.

VEGETABLES & FRUIT | NOVEMBER • DECEMBER 2021

GENERAL

On the cutting-edge with crop-spraying drones

Drones also allow for greater penetration through the crop canopy as well as variable rates of application within the same field.

Unitrans Africa’s 50-year involvement in cutting-edge agricultural innovations across the continent is set to soar to new heights after the company’s recent acquisition of a fleet of the world’s largest spraying drones.

he purchased seven Chinese-made DJI T30 Agras drones, which were developed at a cost of over R400 million, is set to become a game-changer for the agricultural industry across Africa in general and the SADC region in particular. The environmentally-friendly, low-cost T30 drones are already in operation in Malawi and Mozambique, with results exceeding expectations in the areas of spraying precision and the optimal utilisation of chemicals, thereby reducing costs and ensuring each crop’s specific needs are met. “Drones have so many advantages over planes, including being environmentally friendly,” says Unitrans CEO, Rob Hayworth. “Drones use batteries instead of fuel and can spray

at night, whereas a plane cannot, thereby allowing for 24/7 spraying operations. “Drones also allow for greater penetration through the crop canopy as well as variable rates of application within the same field, which is a major advance in aerial spraying worldwide and a first for Africa. This means less water use and ensures that more chemicals go to where they are needed, instead of every part of a field receiving the same amount,” he adds. Hayworth’s comments echo those of a United Nations Food and Agriculture research report that highlighted a noticeable improvement in the growth speed and yield of crops

VEGETABLES & FRUIT | NOVEMBER • DECEMBER 2021

ALGEMEEN

Drone crop-spraying is more cost-efficient, less harmful to humans, environmentally friendly and far less indiscriminate.

that were observed. The report ascribed this to, amongst other things, drones’ ability to collect vast amounts of data, thereby allowing farmers to increase their productivity while reducing costs, human error and environmental damage. Hayworth says that Unitrans, which has been closely involved in the agriculture sector since 1962, has a firm footprint in countries such as Namibia, Botswana, Mozambique, Lesotho, Eswatini, and Zambia, Tanzania and Madagascar plans to use its seven drones in a unique way. “We have a team of engineers, actuaries and agronomists, led by Logan Woolfson, who has designed the best approach for precision agriculture specialising in drone crop-spraying,”

says Hayworth. “With the release of the new and bigger T30, converting all agricultural spraying and fertilising to drones is a ‘no-brainer’ as we can now spray up to 40-50 hectares a day per pilot. Each pilot flies two drones at a time.” The approach is to intelligently understand crop fields by using surveying drones to map all potential spray routes, thereby ensuring optimal applications based on crop health. “We are also confident we can improve efficiency, safety and provide more data-based insights into the crop’s performance,” says Hayworth, pointing to the results achieved already in places such as Dwangwa in Malawi, and the Mozambican areas of Xinavane, Maragra and Lamego. “By using two or even three drones at a time, Unitrans Africa’s strategy is to ensure that more fields can be reached per day. This, in turn, will lead to economic empowerment in terms of locals being upskilled to become drone pilots. This could never happen with planes,” Hayworth adds. “Drone crop-spraying is more cost-efficient, less harmful to humans, environmentally friendly and far less indiscriminate when it comes to spraying. In addition, drone data can help farmers by, for example, identifying crops that are under stress. It’s a game-changer for our operations and a win-win for Unitrans Africa and farmers.”

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INSECT COLUMN

Natal fruity (Diptera: Tephritidae) The Natal fruit fly (Ceratits rosa) is an indigenous polyphagous pest the attacks several commercial fruits, including a wide range of wild fruit species. Ceratitis rosa belongs to a complex of cryptic species and was recently split into two species, C. rosa and Ceratitis quilicii. Host plants of the Natal fruit fly include avocado, peach, plum, stone fruit, apricot, guava, mango, apple, citrus, cashew nut and prickly pear. Its distribution is mainly restricted in eastern and southern Africa. In South Africa, C. rosa is distributed in the northern and eastern parts and along most of the country's coastal areas (including the southwestern areas). At the same time, it is largely absent in the drier inland areas and arid regions. C. rosa is more abundant in hot areas, while C. quilicii is more abundant in cooler areas.

Figure 1: Adult of the Natal fruit fly. Source: https://www.projectnoah.org/spottings/18588034 Figure 2: Mature avocado fruit with star-shaped cracks surrounded by white powder, indicating the oviposition (sting) marks of the Natal fruit fly Source: http://www.avocadosource. com/wac1/wac1_p075.pdf

Nozibusiso Maphumulo IPM-PROGRAMME, NORTH-WEST UNIVERSITY, POTCHEFSTROOM

Natal fruit fly classification: Class: Insecta (insects) Order: Diptera (flies) Family: Tephritidae Genus: Ceratitis Species: rosa

hese species are of phytosanitary importance and can become invasive pests outside their native range, and in other parts of the world, especially in tropical and subtropical areas. The common mode of dispersal and introduction is through commercial shipments of fruits that are infested with larvae. It can also be spread through the luggage of travellers. Females of the Natal fruit fly become sexually mature and lay eggs five days after emergence from pupae and when conditions are favourable. Eggs are laid inside the ripening fruit under the skin surface. Oviposition (sting) sites appear as small brown spots on the surface of the fruit. They lay one to more than 20 eggs. Larvae hatch between 2 to 3 days and develop inside the fruit, and has three larval stages. Larvae leave the fruit once it has matured after 7 to 40 days, fall into the ground, and pupate below the soil's surface. Adult fruit flies emerge from the pupae after 8 to 40 days. Its life cycle ranges from three to four weeks under favourable conditions and two to three months in winter. It has three to six generations per year, depending on the weather and availability of resources. The length of the fruit fly adult is approximately 8 mm. They are brown in colour with reddish-purple eyes. The wings have a pattern of brown bands. Eggs are white, smooth and banana-shaped with a length of 1 mm. First-instar larvae are

minute and translucent with no visible head, while 2nd and 3rd-instars are white to cream-coloured. Mature larvae are 9-11 mm in length. Larvae are typically those of fly maggots – they do not have legs, and the body tapers from the posterior to the anterior end. Blackmouth hooks are visible in 2nd and 3rd-instar larvae. Pupae have a cylindrical shape with rounded ends and a length of 4- 6 mm. Pupae are initially straw-coloured and then turn dark reddish-brown. Natal fruit fly causes damage on both young and older fruits of crops such as avocado, citrus, etc. The larvae feed inside the fruit while tunnelling to the centre of the avocado fruit. Feeding damage often leads to infections by micro-organisms and secondary pests. Larvae cause intensive damage to commercial fruit crops. This then results in heavy losses of fruits. For example, damage symptoms on avocado are noticeable by lesions that appear as puncture marks surrounded by a white powdery substance when the fruit is about golf-ball size. Star-shaped cracks occur in the skin as the fruit develops. When the skin around the lesion is removed, the underlying tissue appears bruised. Traps baited with male lures can be used to monitor this pest. Natal fruit fly can be controlled through sanitation by picking up and burying fallen fruits to avoid attracting fruit flies. Biological control agents for the fruit flies include entomopathogenic bacteria, fungi, nematodes, ants and spiders. Chemical control can be achieved through fruit fly baits using a protein attractant mixed with synthetic or natural insecticides. Sterile Insect Technique (SIT) can also be used to manage fruit fly populations. Enquiries: mashimanenozi03@gmail.com

VEGETABLES & FRUIT | NOVEMBER • DECEMBER 2021

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Blog

Vegetables & Fruit November/December 2021

Articles inside

Bucking the trend

Shade netting makes the difference

Natal fruit fly

ARC aids in keeping the yellow dragon at bay in citrus orchards

Fighting the mealybug

On the cutting-edge with crop-spraying drones

Verbouing van gewasse in hidroponiese stelsels

Plant nutrition concepts in nut crops

New study reveals ethephon’s role in regulating dormancy and flowering in litchi

Relief to farmers in need

WE ARE NOT ALONE – The soil, microbes and human health

The world of avocados

Will dragon fruit take over as super fruit?

New chairperson for Fertasa

Avocado treatment programme with Galilee Export