Vegetables & Fruit November/December 2020 by Vegetables & Fruit

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Litchi production in central Mozambique R40,00

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No 198

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24 20 Nr 198

ISSN 1015-85 37

10 Cover The ever increasing demand for year round supply of subtropical fruit has driven continued increases in internationally traded volumes.

NEWS 5 6 7

Roshdene rises up Sagtevrugtebedryf vereer buitengewone prestasies Prevent losses with accurate and thorough spraying

EDITORIAL Willie Louw (Group editor)

SUBTROPICAL FRUIT 8 Subtropical fruit and tree nut exports 10 For the love of plants 13 Wind protection guidelines for subtropical crops 17 Litchi production in central Mozambique 20 Avocados rise to the occasion despite pandemic challenges 22 Precision irrigation solves problems in the orchard

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TUNNELS & NETTING 24 26 28

Tamaties onder beskerming Drape net on apples and fruit size Control meteorological conditions GENERAL

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GROENTE & VRUGTE | NOVEMBER • DECEMBER 2020

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NUUS

Roshdene rises up With her interpretation of Andra Day’s R&B hit “Rise Up”, 22-year old general agricultural worker, Roshdene Sampson from Sandhoek Farm, De Doorns, won over judges and fans with her incredible voice.

HAT MAKES HER story even more special is that Roshdene did not enter herself in the competition. Her mother, Maria, entered her voice note without Roshdene knowing about it. When the Agri’s Got Talent (AGT) team phoned to congratulate her for being part of the top ten, Roshdene was flabbergasted. The AGT team met up with Roshdene at Sandhoek and announced that she won during a live broadcast via Facebook. “I am so proud of myself and really look forward to what is going to happen next. This is the first time that I win a competition,” an overwhelmed Roshdene said. “I am so grateful for AGT and the team, and for everything that they have done for us. In the past weeks I have really developed as a singer and also as a person.” Jenny Maarman from Diemerskraal, Wellington, was in the second place and incredible rapper Bradwin Jonas, from Rietfontein, outside Ceres, a close third. The finals were recently recorded at ATKV Goudini Spa, Worcester, and shared with the judging panel and AGT Facebook fandom. The judges were impressed with the contestants’ authentic performances this year. The crowd favourite, according to public vote received via WhatsApp or sms, was Sivenathi Ndzakayi from CRI, Citrus Foundation Block, Uitenhage. Earlier, Sivenathi said that the competition has changed his life. “I will forever be grateful for this opportunity. I now know that anything is possible.” Agri’s Got Talent was hosted for the seventh time this year and the goal is to give workers in the citrus, deciduous fruit, table grapes and wine industries the chance to showcase their singing talents. Entries opened in March 2020 and when the COVID-outbreak followed shortly thereafter, the competition was nearly cancelled. The AGT team, supported by the various sponsors, decided on a format change and pushed through with a “new” mostly digital event. “Contestants were partly coached via cell phones with the AGT team visiting them on-farm to complete the training. Logistically it was sometimes a nightmare, but we are immensely proud of this year’s contestants and the competition,” said Thea van Zyl, AGT event coordinator. “Due to COVID we did not have a gala evening and in many ways the contestants were challenged to bring their

GROENTE & VRUGTE | NOVEMBER • DESEMBER 2020

Roshdene Sampson, winner of the 2020 Agri’s Got Talent.

best game and perform in front of a camera without the support of their fans. “We would like to acknowledge Hortgro, SATI, VinPro Foundation, Citrus Growers’ Association and the Western Cape Department of Agriculture for their support in making this project a reality in 2020, a year where everybody desperately needs a bit of AGT magic,” Van Zyl said.

NEWS

Sagtevrugtebedryf vereer buitengewone prestasies Die wêreldwye koronavirus-pandemie het die Suid-Afrikaanse sagtevrugtebedryf genoop om vanjaar sy jaarlikse toekennings digitaal te oorhandig. " ‘n Virtuele oorhandigingseremonie vervang die 45ste gala-aand," het Jacques Jordaan, voorsitter van die toekenningskomitee en uitvoerende hoof van die Inmaakprodusentevereniging (IVP) gesê.

IE SAGTEVRUGTEBEDRYF SLUIT sluit appels, pere, appelkose, perskes, nektariene, pruime en pruimedante, kersies, tafeldruiwe en gedroogde druiwe in, en word veral in die Wes-, Oos- en Noord-Kaap verbou. "Weens die COVID-19 inperkings het ons byna vanjaar die toekennings gekanselleer. Ons het egter gou besef dat landbou, as ‘n noodsaaklike diens, nie anders kan as om juis in dié tyd harde werk, vaardigheidsontwikkeling en betrokkenheid by die gemeenskap te erken nie. Dit is per slot van sake die sleutel tot 'n suksesvolle seisoen," het Jordaan gesê. Drie mense het toekennings ontvang vir uitmuntende

prestasies en spesifiek vir werk op sagtevrugteplase, en vyf vir hul direkte en indirekte bydraes tot die bedryf. 2020 se pryswenners • Spesialis landbouwerker: Rudowaan Rayneil Isaacs • Gevorderde landbouwerker: Lance du Toit • Nuwegenerasietoekenning: Dirk Louw • Navorsing en tegnologietoekenning: Phyllis Burger en Andries Daniels • Bedryfsleiertoekenning: Alexander ‘Boetie’ Kriel • Izethelo Mediatoekenning: Lizma van Zyl • Spesiale Sagtevrugtebedryfstoekenning: Colleen Goosen.

DR PIETER HAUMANN

YEAR END END MESSAGE MESSAGE YEAR FROM FERTASA FERTASA TO TO MEMBERS MEMBERS FROM AND THEIR THEIR CUSTOMERS CUSTOMERS AND www.fertasa.co.za ONS STAAN VIR DIE BESKERMING VAN DIE VOLHOUBARE GEBRUIK VAN KUNSMIS. Fertasa is verbind tot die bevordering van volhoubare grondvrugbaarheid en verbeterde plantvoeding. Fertasa-lede is verbind tot: Ÿ Ÿ

'n Gedragskode. Standaarde deur 'n onafhanklike nakomingsbestuursliggaam geouditeer.

Gehalte produkte.

Toepaslike wetenskaplik-gebaseerde aanbevelings.

Voortgesette onderrig en verbetering.

Die nakoming van wetlike vereistes.

Fertasa - Fertilizer Association of Southern Africa Tel: +27 (0) 12 349 1450 | Faks: +27 (0) 12 349 1463 | E-pos: general@fertasa.co.za Reg. Nr. 1971/000012/08 | VAT Reg. Nr. 4830104164

2020 was literally a once in a hundred years' experience when we think of the Spanish Flu in 1918 to 1921 which cost South Africa 300 000 and the world 50 000 000 lives. Gratefully we are not looking at those sorts of gures with Covid-19. Another reason for gratitude is the record yield for grain crops achieved in 2020. I want to congratulate our members, other companies in the Fertilizer Industry and their customers, the farmers for this exceptional achievement under the difcult Covid-19 conditions. I also want to thank our colleagues from Grain SA, Agri SA and Agbiz for their proactive actions ensuring that the Fertilizer Industry is recognised as an essential service in the food chain. This allowed us to continue delivering service even under Level 5 Lockdown. With this I wish all our members and associates a blessed festive season and a healthy and safe new year. CEO FERTASA DR PIETER HAUMANN

NUUS

Prevent losses with accurate and thorough spraying “I recommend FarmTrack for any wine farm that wants to improve its spraying efficiency,” says Kallie Fernhout, viticulturist and manager of Delaire Graff Wine Estate outside Stellenbosch.

E INSTALLED FARMTRACK, GPS tracking devices, on two tractors more than five years ago as an effective solution to monitor and control daily operations on the farm. “Since our wine estate is only 40 ha in size, every bunch of grapes is of great financial value and we cannot afford to lose a single one,” explains Fernhout adding that they would suffer significant losses should a vineyard row be missed during spraying. It is extremely important for us to ensure that every row is sprayed as accurately and thoroughly as possible.” Fernhout points out that it is essential for calibration to be exact for chemical applications to be effective. “FarmTrack indicates whether a tractor is moving through the vineyard at the correct calibration speed during spraying which saves us thousands of rands. “The tracking system has enabled us to increase the efficiency of our spray program, and as a result, the quality and yield of our crop,” he adds. It is especially useful to Fernhout as a farm management tool. The rest of his time is taken up managing 43 selected vineyards on other farms, from as far afield as Lutzville and Napier, to source additional high quality grapes. “FarmTrack allows me to better manage practical farming

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tasks, such as spraying programs, when I am not physically present,” says Fernhout. “I can remotely, but in real time, monitor the spray accuracy of the vineyards by checking when spraying was started and completed, which rows were sprayed, the time that the driver spent in the vineyard as well as the speed of the tractor. “It allows me to see how long the tractor is stationary while it is being refilled with fuel or the sprayer with chemicals. Being able to determine the correct number of hours worked by the tractor driver is especially helpful when a vineyard is sprayed on a Saturday,” he remarks. Fernhout also uses FarmTrack to reconcile the actual amount of chemicals applied with the quantity recommended for a vineyard. “We can immediately see if too many chemicals are left over in the sprayer’s tank after spraying a vineyard block.” Other benefits for Fernhout include FarmTrack helping to record and control diesel consumption and keeping track of the hours worked by each tractor for service intervals. “We are very happy with FarmTrack. It is an effective tool that assists with planning, cost-saving, efficiency and of course, properly sprayed vineyards,” he concludes. Contact FarmTrack for information. Tel: 021 880 1163 or visit www.farmtrack.co.za.

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SUBTROPICAL FRUIT

Subtropical fruit and tree nut exports Traditionally, subtropical fruit and tree nuts in South Africa were grown in certain provinces with the most conducive climatic conditions, however these days they are grown across the country. For export purposes most subtropical fruit and macadamia nuts are grown in Mpumalanga, Limpopo and KwaZulu-Natal and pecan nuts in the Northern Cape.

HE BASKET OF SUBTROPICAL fruit grown for export in South Africa includes avocados, mangoes and litchis. These are grown primarily in Mpumalanga, Limpopo and KwaZulu-Natal (avocados) and lately also grown and exported from the Western Cape. Avocados Avocados are the main subtropical fruit that is exported from South Africa in terms of volumes. The destination market is predominantly the European Union (EU) and the types of cultivars grown and exported include Hass and Greenskins. When local market demands are high and the prices are good, there is a slight increase in the crop sold locally, causing a drop export volume. In general, over 60% of the crop is exported whilst about 23% goes to the local markets and the rest to factories for processing. The export volumes for avocados showed an upward trend over the past five years, depending on the season, as follow: 2016

12 288 million dollars

2017

9 846 million dollars

2018

19 537 million dollars

2019

12 126 million dollars

2020

15 500 million dollars

For the 2020 avocado season 98% of packhouses are done with packing for the season. The major challenges for the 2020 export crop are smaller sized fruit as well as fruit affected by cold damage in some regions. Macadamia nuts Macadamia nuts were first introduced to South Africa in the 1960â&#x20AC;&#x2122;s and since then have grown significantly. It has grown 20-fold since the 1991 production of 1 211 tons to a massive production of 59 050 tons of nut in shell macadamia nuts in 2019. The total hectares planted up until 2019 were roughly 44 775 with an additional 5 887 new hectares planted during that year. Export inspections on tree nuts were regulated on 29 January 2016 with the macadamia nut in shell standards and requirements being published on 22 April 2016. The PPECB commenced with inspections in 2016. There has been a steady increase in the volumes of macadamia in shell nuts being inspected for exports. The historic production figures of nut in shell macadamia nuts were as follow:

2016

38 000 tons

2017

44 610 tons

2018

56 550 tons

2019

59 050 tons

The national production forecast for the 2020 season is however a bit lower, with an estimate of 49 503 tons of nut in shell. This 16% decline is mostly due to some areas that are still experiencing the long-term impact of the drought from previous seasons. The PPECB inspected 22 045 tons of nut in shell macadamias during the 2019 season. The initial challenge on export inspections was to have enough trained and competent inspectors to do these inspections on time as requested by exporter and we believe it was addressed satisfactorily. Pecan nuts The export volumes for both macadamia and pecan nuts have increased during the past four years. Pecans are produced in all the provinces of South Africa, but volumes produced mainly for export originates from Vaalharts and the Lower Orange River region in the Northern Cape. Pecan trees reach maturity at about 12 years and can live as long as 300 years. Grafted varieties produce fruit in 5 to 10 years, depending on the variety. Pecan nuts have very high protein content and its nutritional value is one of the highest of all fruit grown in South Africa. It is also rich in vitamins, carbohydrates and nut oil. The pecan nut industry grew from a low level of 2 900 tons produced in 2006 to 17 239 tons in 2019. The standards and requirements for export inspections of pecan nut in shell were published on 22 April 2016. The PPECB commenced inspections of nut in-shell pecan nuts for exports during the 2016 season. The historic inspection figures of nut in shell pecan nuts for export were as follow: 2016

8 507 tons

2017

14 242 tons

2018

16 416 tons

2019

16 082 tons

From this 16 082 tons of nut in shell pecans that were inspected for exports during 2019, 2,5% were rejected. Subtropical fruit and tree nuts are an important part of the PPECB Inspection portfolio and significant investments mere made to ensure sufficient capacity to service the demands of producers and exporters. Currently the PPECB has 59 inspectors competent and multi-skilled on these products nationally to ensure compliance to international specifications and requirements.

NOVEMBER â&#x20AC;˘ DECEMBER 2020 | VEGETABLES & FRUIT

Together we grow and sustain your business

SUBTROPICAL FRUIT

For the love of plants Amorentia Estate & Nursery is nestled in the beautiful Politsi valley on the north-eastern escarpment of the Limpopo Province, some 25 km outside of the agricultural town of Tzaneen. Here, you will find a family-run business comprised of the estate with an avocado and macadamia farming operation as well as four nurseries. The love for plants runs through the veins of those who have gone before and those who are here now. According to Lauren Strever, General Manager, they are blessed to be surrounded by people who are as passionate about the industry and plants as her family have always been. Their story began in 1955 when Gary Blight bought the 180 hectares of steep timberland farming-ground. Gary’s youngest son, Howard, was educated in horticulture at The Royal Agricultural University in Cirencester, Gloucestershire, and on his completion in 1973, Howard returned to the Politsi Valley. He raised his three daughters on the farm and Lauren, being the youngest, moved on to Amorentia to join the professional team in 2009, where she is raising her children with her husband Nicholas Strever. More than just a commercial operation, the people of the Amorentia team believe that they are privileged to take responsibility to conserve a piece of indigenous forest in the valley. Social upliftment and extending a right to education is also at the forefront of their intentions. Vegetables & Fruit spoke to Lauren about their organisation, its unique culture and why the nurseries offer what they do.

MORENTIA IS STEEPED in horticultural history. It is alive with stories and plants from all over the world. Arguably the most important import with a great story is, to date, the most widely planted macadamia cultivar in South Africa. Len Hobson, Lauren’s maternal grandfather, selected Beaumont in California in the late 1960’s and the first Ethephon trials were conducted at Amorentia Estate. Len’s selection of Beaumont was fortuitous for the nursery industry, because he quickly discovered that the selection produces its own beautiful root system. Amorentia therefore offers Beaumont as a vegetatively propagated (VP) clonal rooted cuttings and has perfected this method for nearly 50 years. All trees come from original Amorentia mother material where each tree was monitored for its production potential. Therefore, growers are offered the highest yield potential. VP propagation is uncommon in the macadamia nursery industry in South Africa and grafted seedlings are more widely produced and understood. But VPs produce a more even orchard due to the consistency of genetics and they have a superior root system when propagated by superior nurseries with experience. In terms of what the market is looking for, Beaumont produces evenly and consistently year on and it offers a superior product in terms of its oil profile. It’s an excellent nut supplying the ever growing Chinese demand. They also produce all the other widely planted cultivars, namely A4, 816, 814, 791, 842, 849, A16 and more recently A203 and A268 are also available to grow commercially. Grafting requires important methods to ensure even growth in the orchards. Nearly 50 years of macadamia propagation experience sets Amorentia apart from other nurseries in this regard. The Amorentia team are up to date with the latest propagation and fertilization technologies in the industry and continue to explore new ways to improve production to help growers in a shorter amount of time. When talking about avocados, Lauren says they offer all

Amorentia Sweet Dragon Fruit offers an entirely new experience with this super food fruit.

the widely planted cultivars that the industry demands, grafted onto seedling rootstocks. Based on their own commercial avocado production data and data extracted from a national benchmark study performed by Sourcebi Agriculture Data Analytics, Amorentia confidently uses Gautamalan / West Indian rootstocks. They rely on them to produce consistent production and pack-out results. Among other things, the said benchmark study highlighted the role that rootstocks play in the yield and quality of avocado production. Over a six-year period (2013 – 2019), seedling rootstocks yielded the same average tonnage per hectare, but packed out more four kg cartons per hectare than avocados yielded from clonal rootstocks. More recently, Amorentia launched Amorentia Sweet Dragon Fruit which is comprised of a variety of Sweet Dragon Fruit selections offered to commercial growers for an exciting developing market in South Africa. The flesh colours vary from white to pink to red and all have a minimum Brix of 15, making them deliciously sweet. TO PAGE 12

NOVEMBER • DECEMBER 2020 | VEGETABLES & FRUIT

SUBTROPICAL FRUIT

For the love of plants FROM PAGE 10

Nearly 50 years of macadamia propagation experience sets Amorentia apart from other nurseries.

The Amorentia Sweet Snow.

The Amorentia Estate.

Each selection has been named and trademarked under the Amorentia Sweet Dragon Fruit brand. These can be viewed on their website (www.amorentia.co.za). Their names include Sweet Azalea, Sweet India, Sweet Coral, Sweet Snow, Sweet Cloud, Sweet Pink Moon, Sweet Fiery Kiss, Sweet Blood, Sweet

Ballet, Sweet Fuchsia, Sweet Flamingo and Sweet Angel. Amorentia Sweet Dragon Fruit selections can be planted in areas which are suitable to macadamias and avocados but can also be planted in areas with much higher temperatures. Dragon Fruit are a lot less demanding when it comes to water requirements, increasing its suitability to these areas. The fruit is normally available from October to April, varying in regions. According to the Amorentia team, there is a growing market for this fruit. Most consumers have either had a poor experience with Dragon Fruit due to the older, bland tasting selections. Amorentia Sweet Dragon Fruit offers an entirely new experience with this super food fruit. The selections are sweet and tasty and still have all the incredible health benefits. Amorentia’s aim is to make this product available to consumers with the confidence that they are buying the best quality available in terms of taste. The export market is open to this revolution too. Amorentia is working closely with several exciting marketers and exporters – everyone is looking forward to this coming season. One of the challenges Amorentia faces is that of a growing, demanding industry, where growers are often influenced by misinformation. Amorentia strives to deliver excellent trees and advice to commercial growers. “We love what we do because we work with plants daily and live in a valley surrounded by incredible natural beauty with superb growing conditions due to our unique micro climate. Receiving excellent production feedback from our growers over the years adds considerably to the reward of what we do," says Lauren. When it comes to social responsibility, Amorentia supports Thlalefa Combined School, which was built by Howard in 1983. It provides education to all the children of the workers in the valley. Amorentia is actively involved with the Cape Parrots project. The population of the endangered Cape Parrot in South Africa have declined drastically over the last few years. This is mainly due to habitat destruction. During the recent Cape Parrot count, it was reported that the numbers have however increased slightly and there could be as many as 1 500 birds remaining. Currently, the major limiting factor for reproduction of Cape Parrots is the availability of nest cavities. They prefer to nest in dead yellowwood trees and there are few of these trees left. The distribution of the parrots is mainly in the Eastern Cape and KwaZulu-Natal, with a small group in the Limpopo Province in the north of the country. Amorentia Estate has been monitoring the Cape Parrots for a number of years since they were first spotted feeding on pecan nuts on the Estate. Amorentia Estate is home to the three largest Matumi trees in South Africa, with the botanical name Breonadia salicina. The trees have aptly been named The Three Queens of Amorentia. The trees are currently listed on the latest champion tree list released by the Department of Agriculture, Land Reform and Rural Development. Amorentia invites potential customers to visit the nursery for a tour. It is always time well spend in the place “where good things start".

NOVEMBER • DECEMBER 2020 | VEGETABLES & FRUIT

SUBTROPIESE VRUGTE

Wind protection guidelines for subtropical crops Andries Bester SUBTROP

Excessive wind has a negative effect on the growth and production of most tropical and subtropical crops (Holmes, 1994). Since good fruit quality is a prerequisite for the export market, the avocado and mango producers must make use of available technology and knowledge to achieve this goal.

MPORTANCE OF WINDBREAKS Some of the negative effects of excessive wind on the growth and production of avocados and mangoes include: • markedly reduced growth rates in young trees; • root damage in young trees; • girdling (bark damage) at ground level; • bent or fallen trees; • limb breakage; • lesions on the leaves and stems; • water stress; • reduced yields; • poor pollination; • few or no fruit on the windward side; • fruit scarring and secondary infections from fruit scarring; and • fallen fruit. While some of these losses are readily measurable, others do not become apparent until harvest. The SAAGA loss factor benchmark indicates that wind damage, carapace skin and netting were responsible for approximately 30% of all avocado fruit lost to bulk and wastage from 2016-2019 (Winter, 2020). Windbreaks are an obvious solution to reducing wind cull and a requirement in wind prone production areas. Exact thresholds for wind intensity to cause economic losses have not been established for avocado or mango cultivation. Citrus research indicates that winds stronger than 24 km/h cause wind scarring. The minimum threshold for damage is 24 km/h for one hour (Krajweski). Requirements for effective wind protection There are several requirements which must be met for a windbreak to function efficiently, since a badly planned

Figure 1. Wind behaviour with a solid windbreak and one of 50% permeability. An impermeable windbreak produces greater turbulence than moderately dense windbreaks.

windbreak is worse than no windbreak at all. Windbreaks (artificial or natural) are an obvious solution to reducing wind damage and there is little doubt as to the beneficial effects of windbreaks. The geographical location of the orchard will partly determine the type of windbreak required. For example, a planting close to the coast with constant multidirectional winds may require a substantial windbreak around and throughout the planting. However, in drier inland areas windbreaks may only be required against the prevailing wind. The following criteria for effective windbreaks are worth mentioning (Holmes, 1994): "Note that if orchard trees are planted very close to a windbreak, flowering could be reduced due to lack of enough sunlight. It is recommended that a road be left between the windbreak and first row of the orchard." Permeability The more impermeable a windbreak, the greater the increase in turbulence leeward (behind) of the windbreak, reducing the distance of effective protection. Windbreaks should filter and break the force of wind rather than act as a solid barrier. Research has shown that moderately dense windbreaks with approximately 45 to 55% permeability give the best combination between reduction in windspeed and the greatest

protected distance leeward of the windbreak (Fig. 1). In frost prone areas, permeability is important, as windbreaks can be responsible for damming cold or frosty air. Protected area Given a windbreak of approximately 50% permeability, adequate wind reduction will occur up to a distance between eight to twelve times the effective height of the windbreak on the leeward side and two to three times the effective height on the windward side of the windbreak. The effective height of the windbreak is regarded as the difference in height between the actual windbreak and the crop in question. Thus, for a windbreak of 15 m and an orchard tree of 5 m, the effective windbreak height is 10 m. Topography is a critical factor influencing the area of protection afforded by a windbreak. For flat terrain, the greatest protection is provided up to a distance of six times the effective height of a windbreak. However, adequate protection is provided up to a distance of 10 times the effective height of the windbreak. Where land slopes into the wind (2 to 10% slope), adequate wind protection can be as little as six times the effective height of the windbreak, while for land sloping away from the wind, adequate protection may be as great as fourteen times the effective TO PAGE 14

GROENTE & VRUGTE | NOVEMBER • DESEMBER 2020

SUBTROPICAL FRUIT

Wind protection guidelines for subtropical crops FROM PAGE 13

height of the windbreak (Fig. 2). Windbreaks on hill crests will give little protection and may increase wind damage on the leeward slope. Similarly, planting windbreaks at the base of windward slopes is ineffective, since this is already a zone where minimal wind exposure occurs. Such windbreaks would be of greater benefit if planted further up the windward slope. Orientation In areas where the damaging wind direction is predictable during the critical period after fruit set (approximately 12 weeks), windbreaks should be placed at right angles (perpendicular) to that direction. Placed in this position, protection is provided even when the wind shifts up to 30° from the perpendicular. The more the angle exceeds 30°, the less protection is provided downwind of the “break”. Length of the windbreak past the last tree is also a factor. A well-orientated parallel windbreak system is adequate for prevailing winds from either a single direction or two directly opposing directions. If the direction of strong or damaging winds are variable, subsidiary windbreaks must also be considered. The spacing of these subsidiary windbreaks is dependent on the frequency and strength of the secondary winds but will never be closer than that of the main windbreaks. Form Tall narrow windbreaks with near vertical walls generate the least turbulence and therefore it would be advantageous (less turbulence, land and labour saving) to achieve the required 45 to 55% permeability with as few rows of trees as possible. Windbreaks with a lack of lower branches will require lower growing trees or shrubs to act as "fillers" in order to achieve an even permeability. In such instances these additions produce a triangular cross section which has also provided a satisfactory windbreak form (Fig. 3). There is evidence which suggests that windbreaks tending to be circular or semi-circular in form (e.g. mango or avocado trees) are inefficient in reducing windspeed.

Figure 2. Influence of slope on windbreak spacing. "H" represents the effective height of the windbreak.

Height to length ratio A continuous, unbroken line of trees is most efficient since this minimises the increase in windspeed caused at the edges of the windbreak. Windbreaks should be at least 15 times as long as they are high. The efficiency of a windbreak is halved when the width is only twice the height (Fig. 4). This aspect of height to length ratio is especially important when planning access routes and roads within an orchard. Gaps The continuous nature of management activities in orchards demands practical access. It is critical that access through a windbreak does not allow the wind to funnel through and cause severe damage to adjacent trees. Access to all blocks within a protected orchard needs to be well planned. Gaps greater than

1 m wide in wind-breaks result in the funnelling of wind through the gap and ultimately lead to increased windspeed and greater turbulence. The implications of this are the necessity for meticulous windbreak maintenance, especially in single row windbreaks, to avoid the development of gaps within a windbreak. Lower branches must not be cut away and gaps must be filled, either by replacing dead or slow growing trees or by planting "filler" trees to close conspicuous gaps. While replacement trees are given a chance to grow, the simultaneous pruning of adjacent trees on either side of the gap makes the adjacent area more permeable to wind, thus reducing the intense funnel effect. Access routes must be carefully planned in order to minimise the damage to the unprotected area.

NOVEMBER • DECEMBER 2020 | VEGETABLES & FRUIT

SUBTROPIESE VRUGTE Choice of windbreaks Artificial windbreaks Artificial windbreaks include all windbreaks that are erected manually using artificial material such as shade cloth. A variety of polythene mesh products are available with known porosities which makes it easy to select the right permeability. The initial expense may be a little higher than a living windbreak but mesh will satisfy all the requirements of the “perfect” windbreak. Advantages includes: they are instant, are very low maintenance and are more easily installed into an existing planting. The life of the mesh can vary, but most probably last for up to 10 years. However, as artificial windbreaks are normally not as high as living trees, they need to be closer together in order to achieve the same result. There are examples of using poly mesh over the whole planting. For these reasons it is not a common practice to make use of these windbreaks in avocado and mango production in South Africa.

Natural windbreaks When managed correctly, a natural windbreak can be very efficient at wind reduction. The loss of land can be minimised with correct planning to between 3 and 8% (for a standard orchard planting). Natural windbreaks do not present the perfect solution however, as there is evidence which suggests that root competition, shading, competition for water and nutrients and loss of orchard space are all antagonistic factors. The shading effect should be taken into consideration when planting and orientation of windbreaks especially in cooler production areas. If natural windbreaks are not well maintained and management practices adjusted accordingly, competition may negate the beneficial effects of establishing windbreaks. The aim is to optimise profit, which implies a compromise between windbreak competition effects and increase in orchard yield. Some disadvantages of living windbreaks include: • Competition for moisture and nu-

Figure 3. The cross-sectional shape of three types of windbreaks. Narrow, upright windbreaks provide the greatest protection, with circular/spherical-shaped windbreaks providing the least protection to adjacent orchards.

trients if not managed properly; • shading; • material and labour costs; • occupy valuable land; • compete with crops for light; • increased humidity which can slow drying times of foliage and fruit and may favour fungal pathogens; • require valuable water; • interfere with the movement of machinery; • not able to be moved; • may act as a heat trap in summer; • in frost prone areas may dam cold or frosty air if not designed properly; • trees blown over may cause damage; • possible pest and disease build-up in a crop due to microclimate changes; • trees may harbour pests; and • take 5 to 10 years to be fully effective. Perimeter windbreaks with suitable access points should be established at least 12 months prior to planting the orchard trees. They require as much care and attention as the young trees. Irrigation, fertilising and weed control are essential activities. Good soil preparation and weed control prior to planting will favour early and rapid establishment. Windbreaks at Everdon Estate reduced fruit wind damage by 26%, increased the monthly maximum air temperature by about 0,5°C and increased the relative humidity by about 5%. However, yields may well be reduced because of increased competition for light, nutrients and water, shading and reduced area for avocado trees. The number of windbreaks in this hilly, windy area was drastically reduced as orchards matured (Holmes & Farrell, 1993). TO PAGE 16

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SUBTROPICAL FRUIT

Wind protection guidelines for subtropical crops FROM PAGE 15

In selecting the correct tree species, attention should be paid to the following properties which a good windbreak must have (Holmes, 1994): • minimal competition with the orchard crop; • upright growth habit; • fast growth; • low maintenance costs; • should not become sparsely foliated with age; • drought tolerant; • not act as a host plant for orchard pests or diseases; and • if deciduous, it must be in leaf at the critical time. The choice of windbreaks is highly dependent on soil and climatic requirements, disease susceptibility and management needs. Some species that are popular for use in South Africa include: • Casuarina cunninghamiana (beefwood); • Pinus radiata (radiata pine); • Grevillea robusta (silky oak); • Cupressus torulosa (Himalayan cypress); • Populus simonii (Chinese poplar); and • Alnus cordata (Dutch alder). Natural windbreak maintenance Windbreaks perform an important function and should receive similar attention and care as orchard trees. To reduce (or eliminate) competing effects of windbreak trees on orchard trees, windbreaks should be well managed (including correct fertilisation, irrigation and pruning). Fertilisation For the first 3 to 4 years the fertilisation requirements are like those of avocado or mango trees. After this period the windbreak tree will be well established and fertilisation is usually no longer necessary. It is recommended to fertilise heavily for the first 3 to 4 years, as compared to mediocre fertiliser applications which will result in poor establishment and windbreak performance. Soil applications should increase with tree age/size and preferably be spread over the year to prevent root damage.

Figure 4: Percentage change in windspeed behind a long and short windbreak. Figure 4: Percentage change in windspeed behind a long and short windbreak.

Irrigation Most horticultural windbreaks require supplementary irrigation to minimise competition with the orchard. Failure to irrigate is likely to result in competition up to the first four rows of orchard trees. Permanent irrigation is recommended for young trees in drier areas. In high rainfall areas, some tree species will grow well with little irrigation, but requirements vary between species. As the tree grows, it will develop a strong taproot and become less dependent on supplementary irrigation. Pruning Pruning and trimming are needed to maintain the correct shape and permeability of the windbreak. Encouraging a single leader is essential in young trees. • Trim branches to ensure correct permeability – either to thin out dense growth or to encourage denser growth. • Every second year, windbreaks should be trimmed to a hedge form i.e. trim the edges of the outer branches to within 1,5 m of the main stem. • This will create a more "vertical wall" form and will prevent shading of orchard trees. • Remove branches which cause severe shading of the orchard. • Do not remove lower branches. • Prune windbreak roots by deep ripping (1 to 1,2 m) halfway between the windbreak and first orchard row on each side every alternate year.

CONCLUSION Windbreaks are a management tool which producers in wind prone areas can use to improve the financial return of their subtropical orchards. However, each producer must make an informed decision as to the need for wind protection before establishing windbreaks. While there is no perfect windbreak, correct planning, management and maintenance will minimise the competition effects resulting in effective windbreaks and a long-term investment. References HOLMES, M. 1994. Wind protection guidelines for citrus orchards. Subtropica 15: 15-20. HOLMES, M. & FARRELL, D. 1993. SAAGA Yearb. 16: 59-64. KRAJWESKI, A. Windbreaks in Citrus Orchards. CGSA Newsletter. KRUGER, J.A. 2008. Wind protection guidelines. In: De Villiers, E.A. & Joubert, P.H. (eds). The cultivation of mango. ARC, Nelspruit, pp. 116-125. KRUGER, J.A. 2011. Wind protection guidelines. In: De Villiers, E.A. & Joubert, P.H. (eds). The cultivation of avocado. ARC, Nelspruit, pp. 98-106. WINTER, J.A. 2020. SAAGA Loss factor benchmark. SourceBI.

Correction In the May/June issue of Vegetables and Fruit, in the article “Citrus industry working hard to assure record exports” we incorrectly referred to the Citrus Producers Association (CPA), instead of the Citrus Growers’ Association of Southern Africa. Our sincere apo- logies to the Citrus Growers’ Association of Southern Africa (CGASA).

NOVEMBER • DECEMBER 2020 | VEGETABLES & FRUIT

SUBTROPIESE VRUGTE

Litchi production in central Mozambique Regina Cronje ARC-TROPICAL AND SUBTROPICAL CROPS Stephan Schoeman SOETKALMOES CONSULTATION, SOUTH AFRICA During the first week of March 2020, Regina Cronje (ARC-Tropical and Subtropical Crops) and Stephan Schoeman (Soetkalmoes Consultation) travelled to Mozambique to visit small-scale and commercial litchi growers in the Manica Province in central Mozambique. Figure 1 shows a map of Mozambique with the current main litchi production areas.

HE MOZAMBICAN LITCHI industry is still young and expanding, especially under small-scale growers. Some of the oldest trees were planted in 1961 (Fig. 2), but most bearing trees are between 8 and 15 years old (Fig. 3). The youngest trees were planted only a few months ago (Fig. 4). Most litchi plantings are located in central Mozambique, in the Catandica, Vanduzi, Macate, Sussundenga and Manica areas (~650 ha). There are also some plantings near Muxungue and Dombe. Less than 150 ha of litchi can be found in the south near the Boane area. Climatic conditions The climate in central Mozambique is similar to the Malalane (Mpumalanga) region and ideal for early season fruit production. Maximum temperatures in

than 10 ha are planted under ‘Fay Zee Siu’. Some growers also have a few trees of other cultivars to test climatic adaptability. Plant propagation is generally done by means of air-layers (Fig. 6).

Figure 2: One of the oldest litchi trees in Mozambique planted in 1961.

summer range between 25 and 35oC, while minimum temperatures in winter can fall below 10oC. The rainfall season occurs between October and March, with approximately 1 000 to 1 200 mm/ annum, while May to September are the driest months. The soils range from sandy loam to light clay and are generally well drained. Planting distances and cultivars Older orchards were planted at 7 x 4, 6 x 6 or even 5 x 5 m, but were later thinned to 7 x 8, 12 x 6 or 10 x 10 m, because trees were quickly becoming overcrowded and unmanageable (Fig. 5). Newer plantings are spaced at 9 x 6 or 8 x 4 m. The main cultivar is ‘Mauritius’. Less

Figure 1: Map of main litchi production areas in Mozambique (red circles).

Production and constraints Around 400 ha of litchi in central Mozambique are cultivated by small-scale farmers, with litchi production ranging from 1 to 20 ha per farm with an average yield of 4 t/ha. Most small-scale growers farm on dryland and have limited resources to fertilise with inorganic fertilisers. Some small-scale farmers try to use manure and mulching to support tree growth. Due to lack of irrigation at critical periods of fruit development, fruit cracking, sunburn and small fruit size are common. Dryland orchards are supplied with water whenever possible in the form of flood irrigation or by hand for small trees. For this purpose, basins around the trees are made to contain water (Fig. 7). Small-scale growers with higher acreage mostly have irrigation systems and can apply inorganic fertilizers. They also try to prune their trees every year. Some growers make use of basic umbrella-like structures to cover newly-planted trees

Figure 3: Ten-year old (left) and seven-year old (right) ‘Mauritius’ trees near Sussundenga.

TO PAGE 18

GROENTE & VRUGTE | NOVEMBER • DESEMBER 2020

SUBTROPICAL FRUIT

Litchi production in central Mozambique FROM PAGE 17

Figure 4: Eight-month old ‘Mauritius’ litchi planting near Manica.

Figure 5: Old overgrown ‘Mauritius’ orchard with attempts to thin out and rejuvenate.

with grass, as protection against the harsh sun (Fig. 8). Young orchards are often interplanted with annual crops, such as maize, beans and sesame to provide income until the litchi trees start bearing (Fig. 9). The farm size of commercial litchi growers in central Mozambique ranges between 25 and 65 ha, with about 250 ha in total under commercial production. Average yields range from 6-12 t/ ha. Over the past few years, many commercial growers have started to implement pruning and flush control practices with ethephon to maintain tree size and promote flowering. However, in many cases pruning was not done according to schedule or done too late and therefore some orchards are currently at various levels of rehabilitation. In most cases, growers aim to cut back and maintain trees as stand-alone trees. Ethephon has mostly been used as a spot spray, but some growers also use

full cover sprays on dormant trees. Ethephon was not applied in the worst damaged and stressed orchards after cyclone Idai in 2019, resulting in non-uniform flowering. The effects of the cyclone can still be seen. The main production constraint for commercial litchi growers in the Manica area is an inability to irrigate. This is mainly due to poor water quality as a result of gold mining activities along rivers close to farms. Other constraints in the industry include production losses due to small fruit size and fruit cracking for those trees without irrigation, and limited technical knowledge of growers. Where an irrigation system is available, mostly micro sprinklers are used. Most growers use mulching under the trees to reduce soil moisture loss and improve soil quality. Erosion can be a big problem in some areas. In order to contain erosion, growers use contouring, ridging and vetiver (Chrysopogon zizanioides) grass. Because there are sufficient natural bee populations in and around the orchards, only few growers add additional beehives during the flowering period. Some growers plant wild basil (Clinopodium vulgare) (Fig. 10) to keep the bees in and around the orchards, and to support them outside the flowering season. Pests and diseases Similar to South Africa, pest and disease incidences in litchi are also very low in Mozambique. Tree dieback can occasionally occur on sandier soils. Insect damage is very low or non-existent, due to low pest prevalence in litchi orchards and earliness of the fruit. Crop losses due to bats occur in some areas. Postharvest treatment and marketing Currently, there are only two pack-

Figure 6: Litchi air-layers in the nursery.

Figure 7: Flood irrigation for dryland tree with basin around the tree to retain water.

Figure 8: Hand-made structure to cover newly-planted trees with grass for protection against the harsh sun.

houses that can pack litchi for the export market in central Mozambique – one near Manica and one in Chimoio. Due to the distance between farms and packhouses, most growers apply sulphur fumigation on their farms directly after picking and before transport to the packhouse. For that purpose, portable fumigation tents are erected during the harvesting season. Good harvesting and handling practices are applied to keep the fruit as cool as possible until packing. Care is also taken to keep the empty lug boxes in the shade to prevent them from heating

NOVEMBER • DECEMBER 2020 | VEGETABLES & FRUIT

SUBTROPIESE VRUGTE

Figure 9: Litchi interplanted with bananas (left) and maize (right).

up and later also heating the fruit once placed in the lug boxes. The bulk of the production enters the informal local market, due to harvest timing, infrastructure challenges and other practical reasons. Local buyers often only buy fruit that they self-harvest and they bring their own teams for that purpose. They also do not accept sulphur-fumigated fruit. The informal market is able to channel fruit to final customers within hours. Approximately 300 tons of fresh litchis are exported

annually to the European Union, primarily through Westfalia. Some growers are considering litchi processing for juice and canning. Future prospects Future prospects for the litchi industry in Mozambique are positive, because of the favourable climate and earliness of fruit maturation. However, improvement of infrastructure and expansion of marketing channels are essential for the industry to stay viable.

Figure 10: Wild basil plants grown between orchards or around orchard perimeter to support natural bee populations.

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Avocados rise to the occasion despite pandemic challenges Overall, the South African avocado industry had another positive year although the export market was oversupplied mid-season. On the local market, prices and demand remained firm. The renewed interest in health foods bolstered global avocado sales, despite challenges experienced as a result of the coronavirus COVID-19 pandemic.

HE SOUTH AFRICAN Avocado Growers’ Association (SAAGA) reported that 15,5 million 4 kg cartons of the fruit were exported during the season. Derek Donkin, CEO of SAAGA, said that although the shutting down of the hospitality sector affected the sale of green skin avocados particularly, retail prices were not affected as the usual buyers were still active. “In the European Union people were looking for something special to add to their meals at home, so there was no drop in demand as retail sales remained strong.” Locally avocados also performed well on the markets, which Donkin ascribed to locked down consumers wanting nutritious food, but also something special to add to home cooked meals. “There was strong demand from a retail point of view and even the informal sector remained buoyant. In addition, branded avocado masks were distributed at the markets, which kept the product top of mind amongst hawkers. There was also a rise in e-commerce sales, where consumers bought through online platforms.” The latter trend has been spurred on by those looking for extra income streams, knowing that avocados are a high demand, high value product. It also coincided with SAAGA pivoting their marketing strategy to remain in full sight of consumers, turning their attention online as consumers increasingly turned their attention to social media. Lockdown necessitated a change in marketing tactics, away from live events and in-store activations, towards online activities. SAAGA was able to launch the season the

week before lockdown and from there, efforts were focused on television, social media influencers and digitorials. Since online traffic and television viewership increased dramatically during the lockdown, this worked in SAAGA’s favour. With confusion still prevalent among consumers regarding green and dark skin avocados, educational campaigns continued in the form of comedy skits on YouTube, capitalising on consumers’ appetite for laughter during the lockdown. Donkin added that there was a high level of engagement on social media with SAAGA’s campaigns, which he believed was as a result of having a desirable product whose value was continuously touted by media and influencers. Once the much-craved takeaways started operating again, the Add an Avo campaign continued in a national pizza chain, which boosted sales in the hospitality sector. The nutritional value of avocados was also an advantage the marketing campaigns could focus on to boost sales, since health food has been in high demand during the pandemic. The season not only ended on a high note in terms of demand, but Donkin expressed much optimism over the production season that lay ahead, and the continuing upward trajectory of sales. “Currently flowering looks promising in avocado orchards, although there is concern over water levels in dams to get us through the season. Volumes will increase as new orchards come into production and as such SAAGA continues its work on opening up new markets, particularly in Japan, China and India.”

NOVEMBER • DECEMBER 2020 | VEGETABLES & FRUIT

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Precision irrigation solves problems in the orchard The avocado industry is taking great strides in adopting precision farming practices. Precision irrigation is an important piece of the puzzle in completing the precision farming puzzle.

NCREASING ECONOMIC PRESSURE on farmers has shown that it is often not feasible anymore to have an average harvest. “Farmers are increasingly faced with the reality that they need to adapt to survive. They learn that smart decision-making can deliver a larger profit margin,” says Jovan Erasmus, agronomist at Netafim South Africa. These realisations lead to more intensive farming on the one hand and more efficient use of resources on the other. Precision irrigation solutions support both. As mentioned, each tree must be supplied with enough water during its peak water demand periods. “In this context, it is important to consider both system design and irrigation scheduling. The system must be designed with the capacity to deliver enough water during these peak water demand periods and it is important that you understand the capabilities of your irrigation system. We must know how much water to deliver and when to deliver it in order to not under or over irrigate at any stage. “Knowing that a tree’s water demand peak during certain periods makes it is easy to mistakenly give too much water when adjusting for increased demand. The goal is to reduce tree stress, which can be caused by both under and over irrigation. This is why scheduling must be precise with the necessary calculations made when planning the system and during active irrigation.”

Overcome challenges No farmer is a stranger to challenges in the orchard or field. Among the many challenges avocado farmers face are alternate bearing, fruit drop and orchards on steep topographies. Precision irrigation and the advanced solutions offered by Netafim South Africa can assist you in overcoming these and many other challenges.

“In most avocado-producing areas, steep and uneven orchards often lead to lower productivity. We can combat this with proper soil preparation, well-designed irrigation systems and the right irrigation technology, such as pressure-compensated drippers.” Jovan emphasises that soil preparation is a very big part of irrigation success and achieving higher productivity. “That is where everything starts. If soil preparation was done properly, your precision irrigation system can reach its full potential. Proper soil preparation will allow you to create a healthier root-zone that can be better managed. In a deeper and wider root-zone you can manage both water and fertiliser application better to minimise tree stress.” The fact that you are in full control of water and fertiliser application, places the power in your hands against challenges such as alternate bearing and fruit drop as you can adjust applications to phenological stages and conditions to precisely manage the tree’s reserves. More with less Remember that there is no silver bullet in any agricultural industries. It is about doing the necessary research and planning to find a solution for your circumstances and continuously adapting to more efficient farming practices. “We have to make smart decisions now to benefit later; farming is not a short-term activity. The industry must shift towards using fewer inputs more efficiently to grow more. If you take on the challenge with the right experts by your side, you can eliminate many inefficiencies and gain better control of your entire production system to finally grow you profit margin.” Visit www.netafim.co.za, send an email to infoza@netafim. com or contact us at 021 987 0477 for more information.

Blaaspootjies

– klein jakkalsies wat die boorde verniel Charla Meyer – Villa Crop Protection

Uitgedroogde makadamiablomme agv blaaspootjieskade Foto: Charla Meyer

Blaaspootjieskade aan nuwe groei Foto: Charla Meyer

Blaaspootjies is maar ‘n alte bekende doring in die vlees van produsente wat met sub-tropiese gewasse boer. Hierdie klein, fyn insekkies is jaarliks verantwoordelik vir enorme opbrengsverliese. Eendersyds weens blomme en klein vruggies wat uitdroog en afval, en andersyds weens kosmetiese skade op volwasse vrugte soos sitrus en avokado's. Groeivertragings op jong boompies waar die nuwe groei herhaaldelik aangeval word, kom algemeen voor. Herhaalde skade op die nuwe blaargroei van produserende bome kan lei tot ‘n koolhidraattekort in die boom (Bright, 2015) – iets wat die volgende seisoen se drag negatief kan beïnvloed. Die volwasse wyfie se lewensduur is sowat 30 – 45 dae waartydens sy tot 300 eiertjies lê. Die eiers broei binne 2 – 4 dae uit, na gelang van die weersomstandighede. Die insek se onvolwasse lewensstadia duur 4-6 dae waartydens die larwes voed op die sagte plantweefsel van blomme, blare, stamme en petiole. (Graeme Murphy - Greenhouse Floriculture IPM Specialist/OMAFRA). Dit is gedurende hierdie tydperk wat groot skade aangerig word omdat plantselle vernietig word wanneer die insek die inhoud daarvan uitsuig. Die papiestadium duur ongeveer 5 dae en vind gewoonlik plaas op die grond. Daar is wel genoteerde gevalle waar die papies op laaghangende blare op die grond voorgekom het. (Graeme Murphy Greenhouse Floriculture IPM Specialist/OMAFRA). Tydens hierdie fase ontwikkel die vlerkies. Volwasse blaaspootjies is swak vlieërs, maar verprei vinnig deur boorde met die geringste luggie wat trek. Hierdie insekte plant baie suksevol voort en as gevolg van hulle kort lewenssiklus vermeerder hulle eksponensieel onder gunstige omstandighede. Dit is dus belangrik om toe te sien dat getalle onder beheer bly. Vroeg in die ontwikkeling van die makadamiabedryf was die aanname dat blaaspootjies net kosmetiese skade aan die neutomhulsel veroorsaak. Die omhulsel verkleur ligbruin of silwer sonder at enige noemenswaardige insekskade aan die dop of kern waargeneem kan word. Ons weet egter nou dat die insekte se voedingswyse ook makadamiablomme laat uitdroog en jong blare laat omkrul. Die plantselwande gee mee wanneer die insek se monddele die selwand penetreer en die inhoud van die plantsel uitsuig. Die plantselle word hierdeur totaal vernietig.

Geregistreerde aktiewe bestanddele vir die behandeling teen blaaspootjies is chloorpirifos, spinetoram en imidakloprid. ‘n Nuwe registrasie in die Villa makadamiaportfolio is IMIDOR 350 SC met die aktiewe bestanddeel imidacloprid teen 350g/l. Die produk word toegedien teen 18ml/boom in 2L water met die deurdrenkingsmetode direk om die basis van die boom.

Vir meer inligting kontak Villa Crop Protection 011 369 2233 Charla Meyer • cmeyer@villacrop.co.za • 072 585 4243

TUNNELS & NETTING

Tamaties onder beskerming Johan Stronkhorst SAKATA

Gesonde tamatieplante geproduseer onder optimale omstandighede.

AMATIES IS EEN van die belangrikste groentegewasse wat geproduseer word en vorm deel van die meeste mense se stapeldieet. Al hoe meer navorsing dui op die verskeidenheid voordele wat tamaties as deel van ’n gesonde lewenstyl vir die mens inhou. Tamaties is dus op groot aanvraag regdeur die jaar. Marktendense wys dat die prys van tamaties grootendeels deur vraag en aanbod bepaal word. Dit plaas produsente onder groot druk as gevolg van stygende insetkoste, wisselvallige opbrengste en moontlike kleiner aanvraag op die markte. Hierdie faktore dwing die produsent om noukeurig te beplan om te verseker dat tamaties op die regte tyd met die hoogste moontlike opbrengs en kwaliteit mark toe gaan. Wêreldtendense in die verbouing van tamaties is besig om radikaal te verander, met verbouing onder beskerming wat nie meer net ’n luukse is nie. Die verandering in klimaat en die aanvraag na hoër kwaliteit, gekoppel aan druk van die verbruiker om minder chemiese stowwe te gebruik, noodsaak die produsent om sy produksie te optimaliseer. Eenvoudige strukture en selfs nethuisstrukture kan die opbrengspotentiaal van ’n tamatie-oes verbeter, deurdat die produsent verskeie faktore beter kan beheer. Die belangrikste faktor is om die omgewing tot so ’n mate te bestuur dat die plante optimaal produseer en maksimum opbrengste behaal word, op die gegewe oppervlakte. Ander voordele sluit verbeterde sanitasie in, wat veral insekvektore beter kan

Gewasverbouing in Suid-Afrika word jaar na jaar onder toenemende druk geplaas. Die uitdagings uit ekonomiese oorde word al hoe groter, maar omgewings- en klimaatsverandering speel ook ’n groot rol.

beheer. Plante wat nie blootgestel word aan stremming van die omgewing of siektedruk nie, produseer derhalwe beter. Die bemesting en besproeiing van enige variëteit is ’n kritiese bestuursaspek wat die potensiaal van die gewas bepaal. Hierdie twee faktore het ’n invloed op al die ander aspekte, soos plaagbeheer, siekteweerstand, kwaliteit en opbrengs. Dit is belangrik om te kyk plant se balans in aanmerking te neem, maar in hierdie artikel is die fokus meer op die rede vir produksie onder beskerming en wat die invloed daarvan op die plant is. ’n Plant wat minder stremming ervaar se produksiepotensiaal is beter en dit kan ook die eksterne omgewings- en klimaatstoestande beter hanteer. Temperatuur is een van die grootste faktore wat gewasproduksie beïnvloed, maar dit gaan gepaard met relatiewe humiditeit en ligintensiteit of stralingsenergie. Met temperatuur kan beide té hoë of té lae temperature ’n invloed hê op die plant, veral met blomvorming en vrugset. Die ideale temperature vir bestuiwing is tussen 23°C en 26°C, met die minimum en maksimum tussen 18°C en 30°C. Temperature van 28°C tot 30°C beïnvloed nie werklik die plant se biologiese of fisiologiese proses nie, maar dit het ’n baie groot uitwerking op vrugset. Té hoë temperature kan lei tot vertraagde blomvorming van die eerste tros, minder trosse per plant en minder blomme per tros. Dit kan ook daartoe lei dat die kwaliteit van stuifmeel afneem en dat die stempel (vroulike deel van die

blom) verleng is, wat tot gevolg het dat bestuiwing nie behoorlik kan plaasvind nie. Hitte-stremming verkort ook die gewas se potensiële groeiperiode. Té hoë temperature kan verder daartoe bydra dat die vroulike dele van die blom misvorm is, wat op sy beurt weer kan lei tot nie-bemarkbare vrugte. Daar kan verder hormonale wanbalanse voorkom wat verskeie prosesse in die plant en vrugte beheer. Hoë temperature beïnvloed ook die volgende: ensiem-aktiwiteit, membraam-integriteit wat die opname van voedingstowwe bepaal, energie-sintese, huidmondjie-aktiwiteit en gaswisseling, asook verlaagde koolhidrate. Verlaagde koolhidrate lei direk tot verlaagde vrugset. Hoë temperatuurskokke kan daartoe lei dat die plant se weerstandmeganismes geïnhibeer word en daartoe lei dat patogene die plant kan besmet en siektes veroorsaak.

Aantreklike tamatietros met uitstekende vrugset.

NOVEMBER • DECEMBER 2020 | VEGETABLES & FRUIT

TONNELS & NETTE

Nie-bemarkbare vrugte as gevolg van temperature buite die optimaal.

Koue temperature, laer as die ideaal, kan veroorsaak dat die vrugbeginsel misvorm is en dit kan veral die bemarkbaarheid van vrugte beïnvloed – verskeie fisiologiese afwykings kan word aan koue temperature toegeskryf. Die twee stadiums waar temperatuur krities belangrik vir die tamatieplant is, is blomvorming, wat vir beide lae en hoë temperature sensitief is en kan veroorsaak dat die blomme afspeen, en vrugte, wat as gevolg van te hoë temperature geneig is om van die plante af te val. Altwee stadiums kan ’n negatiewe uitwerking op die finale

opbrengs hê. Koeler temperature, veral nagtemperature van 14°C en laer, lei daartoe dat die eerste vrugte aan die plant baie lelik vertoon, met ’n kenmerkende bootvorm en groot bloment. Aardverwarming, wat tans ‘n gonswoord is, het die kollig geplaas op die uitwerking daarvan op gewasverbouing, veral opbrengs. Selfs ’n enkele graad of twee bó die optimaal kan ‘n groot invloed hê. Temperature van 3°C tot 4°C hoër as die optimaal, kan die potensiële opbrengs van tamaties met 15% tot 35% verlaag. Aardverwarming se invloed is egter nie die enigste nadelige effek nie. Ongelukkig kan die keuse van tonnels of selfs skadunetstrukture ’n groot bepalende faktor by opbrengs wees. Die verkeerde struktuur wat nie ontwerp is sonder om die plaaslike omgewing in aanmerking te neem, kan dodelik vir gewasverbouing wees. Te veel strukture staan verlate, omdat dit nie ekonomies bestuur kan word nie, met te hoë temperature

en swak ventilasie as die hoofoorsake hiervan. Sakata Saad, as ’n wêreldwye maatskappy, is op die voorgrond met die ontwikkeling van nuwe variëteite en siekteweerstand en gee graag tegniese advies aan produsente ten opsigte van bemesting, besproeiing en algemene gewasbestuur. Die Sakata-span se kennis en ervaring word toegepas om produsente by te staan wat in Suid-Afrika gewasse verbou wat aangepas is vir die plaaslike markte met al die vereistes wat daarmee gepaard gaan. Besoek gerus Sakata se webwerf (www.sakata. co.za) vir meer inligting. VRYWARINGSKLOUSULE: Hierdie inligting is op SAKATA se waarnemings en/of inligting van ander bronne af gebaseer. Aangesien gewasprestasie afhang van die interaksie tussen die saad se genetiese potensiaal, die fisiologiese eienskappe daarvan en die omgewing, bestuurspraktyke ingesluit, gee SAKATA geen waarborg vir gewasse se prestasie, relatief tot die inligting. Hulle aanvaar ook geen aanspreeklikheid vir enige verlies, direk of as gevolg daarvan, wat te wyte aan enige oorsaak mag ontstaan nie. Lees eers Sakata Seed Southern Africa (Pty) Ltd se verkoopsvoorwaardes voordat saad bestel word.

Sakata Kwaliteit saad

Inga*

Nerine*

SVTH6995*

* Eksperimenteel: Hierdie variëteit is steeds eksperimenteel, maar registrasie is reeds ingedien vir Suid-Afrikaanse kultivar lysting.

Tel: 011 548 2800 www.sakata.co.za e-pos: info.saf@sakata.eu

TUNNELS & NETTING

Drape net on apples and fruit size Angelique Pretorius and Nordely Wright OROAGRI

Shade nets on fruit trees are used to provide protection from hail, sunburn, wind damage as well as mitigating damage caused by birds and some insects. High light intensity can result in extreme temperatures and high UV-rates. In regions with abundant sunshine, shade nets can be a tool to use to improve fruit quality and pack-out.

HIS IS MOST applicable for green apple varieties such as Granny Smith (GRS) and Golden Delicious. To mitigate sunburn on fruit, shade nets reduce the light intensity in the canopy and have the potential for manipulating leaf gas exchange, light quality and quantity in orchards and can therefore affect overall production. Drape net is a non-structured and cost-effective shade net option. The high incidence of sunburn in many GRS orchards in the Elgin-Grabouw-Vyeboom-Villiersdorp area (EGVVarea) has led to growers exploring additional options such as drape netting to protect fruit against sunburn. Covering orchards with drape nets artificially creates a new environment for apple production. Lowering light intensity in the canopy, however can make fruit more susceptibility to physiological disorders. For example, lower light intensity within a selective part of the canopy can lead to weaker bud development and therefore lead to smaller and less fruit present in the most shaded areas of the tree. In order to evaluate the effect of black drape nets on fruit quality and other production parameters, trials were conducted in three commercial GRS apple orchards of Fruitways Farms. The trials were conducted under Angelique Pretorius by Fruitways Agri Services as part of an ongoing project, with Jeromeo Mento as the trial co-ordinator. Treatments consisted of a factorial trial design with drape net and no net in combination with and without a Cropbiolife application. Cropbiolife is a new generation biostimulant proven to upregulate photosynthesis. As black drape nets influence orchard climate parameters and tree response, changes in pruning, thinning, irrigation and incorporation of other pre-harvest management practices (i.e. PGR use) are required to maximise the productivity of GRS orchards under drape net. Drape nets were erected 50 to 60 days after full bloom. Cropbiolife treatments were applied according to the standard three sprays application programme at 500 mL/ha per application. Sensors set up in GRS tree canopies under drape net and outside drape net, show that drape net increased the relative humidity between 20 and 40 percent and reduced temperatures on average by 4°C to 7°C or higher on very hot days. Fruit was sampled at the top and bottom of the canopy as well as from the inside and outside of the canopy . As expected, sunburn was reduced significantly under drape net improving fruit quality. Data showed a reduction in fruit size with drape net, especially related to canopy position as seen in the graph provided. Conversely, fruit size was better maintained on the one trial site where additional hand thinning was conducted. The use of Cropbiolife, upregulating photosynthesis, significantly mitigated the fruit size loss under

Figure 1: Fruit size is reduced when drape net is used, but can be mitigated with the application of Cropbiolife.

drape nets, especially for the most shaded canopy positions. Cropbiolife as well as canopy position influenced the total soluble solids (TSS) of the fruit. The management of GRS trees under black drape nets needs to consider pruning (both dormant and summer pruning), adjusting irrigation as less water is needed, and possibly incorporating biostimulants to help improve photosynthesis and managing crop load and thinning practices as shade affects fruit set. It was also noted that woolly apple aphid (WAA) was more prominent under drape nets and it is of upmost importance that the grower will need to review their WAA pest management program when making use of black drape net. Drape net is a medium-to-large capital investment and it is essential to use the shading effect of the net to its highest potential by mitigating sunburn in a GRS orchard. However, drape netting cannot be recommended without additional management practices to mitigate the artificial shading effect and the negative effects it poses on fruit size and tree architecture over several seasons. Readers who would like any technical information or any details about the trial, please do contact Oroagri at nwright@ oroagri.com. Control & Cropbiolife

Control

Net & Cropbiolife

Net only

Figure 2: The differences between the applications.

NOVEMBER • DECEMBER 2020 | VEGETABLES & FRUIT

BENEFITS OF CROPBIOLIFE

Ca2+ Maintain tree energy levels throughout the growing season

Enable the tree to handle higher fruit load

Promote healthy rhizosphere environment

Enhanced root development

Improved mineral content of fruit

Induce systemic resistance

THE CROPBIOLIFE PROGRAMME

= 3X CROPBIOLIFE

APPLICATIONS

SET AND FRUIT RETENTION

1st Spray

RETENTION AND INCREASED FRUIT

2nd Spray

ACT / WET 36 / 1947 REG. No ZAR B4018 • FERTILIZER GROUP II • NAM NF0918 • COPYRIGHT © OCTOBER 2020 • ALL RIGHTS RESERVED ORO AGRI, CROPBIOLIFE and OROWET are registered trademarks of Oro Agri SA (Pty) Ltd.

IMPROVED COLOUR AND FRUIT FINISH

3rd Spray

TUNNELS & NETTING

Control meteorological conditions South African farmers have faced enormous challenges due to drastic climate conditions. Some farmers have experienced one extreme to the next, from severe drought and high temperatures to heavy rains, which lead to flooding and hail storms – and as of late, the COVID-19 pandemic and the national lockdown.

ESPITE THESE OBSTACLES, this year South Africa is expecting to export around 22 to 24 million cartons of soft citrus. This figure shows growth from last year's 18 200 million cartons, even with the national lockdown and restrictions. Citrus Growers’ Association of Southern Africa (CGA) CEO Justin Chadwich says the region is forecasted to see exports rise by 13% year-on-year to 143 300 million cartons in the 2020 season. The growth is largely as a result of new orchards coming into production and good rains across some regions. The latest additions of Multiknit were displayed at Nampo 2019, such as the hail release structure and their load testing structure. These structures demonstrated the quality and strength of the SpectraNet range. The load testing demonstration was a 2 m x 2 m structure covered with SpectraNet Code 20. They loaded the structure with 500 kg on the Sunday before Nampo, and left it like that

for the entire week. At the end of Nampo, the team decided to have a bit fun. A cut was made in the fabric to demonstrate the lock-stitch pattern, which will not fray when cut. One of the Knittex sales consultants climbed on top of the 500 kg load. It held true to demonstrate the quality and strength. A well-constructed shade house provides a protected microclimate, ideal for crops to thrive under. It protects crops from harsh weather conditions such as wind and hail damage. In hot climates, Knittex shade netting reduces heat and light intensity, which causes sunburn on crops. Shade netting can also help benefit water efficiency as it reduces the amount of evaporation from free water surfaces.   Knittex is a manufacturer of high quality knitted fabric that is durable and 100% recyclable. The range provides producers with the highest results and best return on their investment. This is backed by years of research and development to ensure that their nets have a guaranteed lifespan of 10 years or more.

PROTECTS YOUR CROP AGAINST DAMAGE CAUSED BY SEVERE WEATHER CONDITIONS

wind, sunburn, hail damage, birds & larger insects

PROTECTING YOUR

CROPS FROM THE 2

+27 (0)11 692 1658 www.knittex.co.za clientliaison@knittex.co.za

ALGEMEEN

Control early blight (Alternaria solani) on potato Potato early blight is caused by the fungus, Alternaria solani L. First observed in South Africa in the early 1900’s, the disease causes severe premature defoliation late in the season, which negatively impacts overall yield by reducing the plant’s photosynthetic capacity.

ARLY BLIGHT IS WIDESPREAD in most areas where potatoes (and tomatoes) are grown, with higher prevalence in tropical and temperate areas, and in production areas under irrigation. In South Africa, potatoes are grown in 14 main regions on more than 53 000 ha, yielding an annual crop in the range of 2,5 million tons (2019). It is estimated that early blight infections can cause yield losses ranging from 20% on average to 60% in extreme cases. At an estimated average

yield of 50 t/ha, a 20% loss equals a thousand 10 kg pockets, which translates into a financial loss of as much as R40 000 per hectare. The primary inoculation in a season originates from mycelium or conidia that overwintered in infected plant debris, tubers and soil or host plants from other species in the Solani family. Being polycyclic, the pathogen can achieve many infection cycles in a season, but the disease needs free water, primarily on the leaf surface, to cause infection and reproduce.

29DALA (Photo – Petrus Makoro).

Although good agricultural practices support successful disease management, preventative fungicide control remain the most effective way to control A. solani. However, efficiency depends heavily on the timing and coverage of the application, especially reaching the lower, older and inside leaves of the plant in sufficient quantities. Well planned preventative spray programs, where active ingredients are rotated to manage potential resistance development, are thus critical to success. André Labuschagne, complain lead for potatoes at Syngenta SA, says that Syngenta recently registered MIRAVIS® Duo (L10750), an SC formulation with 75 g/l ADEPIDYN™ + 125 g/l difenoconazole per litre formulated product. Used as a preventative spray, the product gives excellent long-term control of A. solani on potatoes by combining the well-known efficacy of difenoconazole (present in Score® L5132 and in combination with AMISTAR® technology in AMISTAR™ Top L7898) with a novel active compound called ADEPIDYN™. The combination of two active ingredients with different modes of action also allows for a simpler disease control program, broader disease control spectrum, fewer sprays and simplified resistance management in the field. TO PAGE 30

GROENTE & VRUGTE | NOVEMBER • DESEMBER 2020

GENERAL

Control early blight (Alternaria solani) on potato FROM PAGE 29

ADEPIDYN or pydiflumetofen (ISO common name) is a FRAC group 7 active ingredient with a SDHI (succinate-dehydrogenase inhibition) mode of action. It belongs to a new chemical group called N-methoxy-(phenyl-ethyl)-pyrazol-carboxamides, part of the wider carboxamides family of Ai’s. SDHIs inhibit the germination of the conidia of target pathogens by de-activating the Complex II SDH enzyme in the mitochondria, which disables respiration and thus suppresses the ability to generate energy. Difenoconazole, a proven wide-spectrum fungicide, provides a different mode of action as it stops the development of fungi by interfering with the biosynthesis of sterols in cell membranes (FRAC group 3). The high intrinsic activity of ADEPIDYN allows for high performance at low rates. It also exhibits excellent rain fastness due to the outstanding spray retention on leaf surface and rapid uptake into the wax layer to create a reservoir. ADEPIDYN™ exhibits longer lasting effective control due to its slow movement into the leaf tissue and xylem over a period of 2-3 weeks. Although the translaminar and xylem systemic properties of ADEPIDYN are relatively slow, the molecule has significant biochemical potency and can therefore deliver disease control away from the point of application over a prolonged period. Apart from also being rain fast and

Miravis Duo @ 500 ml/ha; 35 DALA (Photo – Petrus Makoro).

its activity not influenced by the climatic conditions, difenoconazole exhibits strong translaminar activity and is translocated quicker and systemically through the plant, resulting in a long-lasting residual effect. Difenoconazole also has curative properties, allowing control of the pathogen to some extent after infection. André emphasises that MIRAVIS Duo is intended to be used as part of a preventative spray programme to control early blight on potatoes. It should be sprayed at intervals of 7-10 days when

Untreated 35 DALA (Photo – Petrus Makoro).

Kontrole - boomopbrengs

18.6 kg

Kelpak - 3 x 0.3%

20.1 kg

Kelpak - 5 x 0.2%

21.4 kg

Een aan die boom is beter as twee op die grond Beter set en neutretensie beteken meer neute asook ‘n hoër kerngewig per boom. Kelpak, die natuurlike seewier ekstrak is wêreldwyd deur wetenskaplike proewe bewys om neutboere se opbrengs en wins aansienlik te verbeter.

ALGEMEEN

climatic conditions favour the development of early blight. It should not, however, be sprayed more than four times in a growing cycle, with no more than two consecutive spray blocks before alternating with products from a different FRAC group, such as BRAVO® 720 L7005, AMISTAR Opti L6230 or AMISTAR L6230. Care should also be taken regarding maximum sprays per season when MIRAVIS Duo is alternated with SCORE® or AMISTAR Top, as both also contain difenoconazole. MIRAVIS Duo should be applied at a rate of between 500 ml/ha and 1 333 ml/ha in a spray volume of between 200 L and 700 L of water, using the higher rate and shorter spray interval when disease pressure is high. When used in tank mixtures, MIRAVIS Duo should not form part of more than 50% of the total sprays over the season. It is advised to use MIRAVIS Duo with Compliment Super L8169 (CS rate of 100 ml/ha). As ADEPIDYN has such a relatively long residual action, it is beneficial to include MIRAVIS Duo in an early preventative spray programme in areas with known high A. solani pressure to control the disease right from its very beginning. According to André, MIRAVIS Duo is an excellent, easy-to-use product for potato farmers to control early blight. Growers can be assured of a quality product that is optimally formulated and guaranteed to deliver consistent results if used according to label specifications. Importantly, growers also benefit from the support of Syngenta’s experienced team throughout the season. References: A review of early blight of potato (2001) J E van der Waals, L Korsten & T A S Aveling. African Plant Protection 7(2): 00–00. Early blight in South Africa: Knowledge, attitudes and control practices of potato growers (2003) J E van der Waals, L Korsten & FDN Denner. Potato Research 46 (2003/4) 27-37 https://www.potatoes.co.za/

APN 25 gai/ha + Complement Super 21 DALA. Untreated in forefront versus treated plants in the background. (Photo – TLP Adri and Kobus Beyers).

Photo – TLP

GROENTE & VRUGTE | NOVEMBER • DESEMBER 2020

alla

wêreld!

Een doeltreffende aktief: Beskerm jou druiwe teen poeieragtige meeldou met een aktiewe bestanddeel wat residubestuur vir uitvoere vergemaklik. Eenvoudige toediening: Verpak in ’n eenkan-oplossing en reënvastheid binne 1 uur verseker ’n sorgvrye spuitplan. Een veilige produk: Blou etiket status met wye spektrum van mengbaarheid en gewasveiligheid op druiwe. Doeltreffend. Slim. MIRAVIS®.

LEES DIE PRODUKETIKET VIR VOLLE BESONDERHEDE. MIRAVIS® bevat Adepidyn™ (pydiflumetofen) (Reg. no. L10761, Act 36 of 1947) VERSIGTIG. MIRAVIS® is ‘n geregistreerde handelsmerk van ‘n Syngenta Groepmaatskappy. Syngenta Suid-Afrika (Edms) Beperk, Privaatsak X60, Halfway House, 1685. Tel. (011) 541 4000. © Syngenta Ag, 2000. Kopiereg op hierdie dokument word voorbehou. Alle ongemagtigde reproduksie word verbied.

@SyngentaSA

ALGEMEEN

Powdery mildew in grapes It is estimated that powdery mildew (causal agent: Uncinula necator [Schw.] Burr.; syn. Erysiphe necator Schw.; Anamorph: Oidium tuckeri Berk) is globally the most important fungal disease in vineyards. The disease was first described in North America in 1834 and the first reported incidence of the disease in South Africa was in 1880 in the Constantia region, although it is estimated the disease was introduced in South Africa around the 1860’s.

HE DIRECT ECONOMIC impact of powdery mildew can be attributed to the loss of quality of marketable product. In table grapes visually infected bunches cannot be marketed and when petioles and stems of bunches are infected it has a significant impact on storage life of grapes. Infected berries might also split or crack, creating entry points for other pathogens such as Botrytis cinerea and sour rot causing organisms. In wine grapes, apart from the fungus itself contributing to off-flavours, infected fruit tend to have an increased acid concentration. It has also been reported that red wine made from infected fruit has a lower colour intensity caused by a lower anthocyanin concentration. Losses are attributed to lower yield due to loss of photosynthetic potential and respiration capacity in affected leaves, as well as a reduction in bud survival after winter. Estimations are that around

50% of fungicidal control measures in grape production is focused at controlling powdery mildew. Powdery mildew symptoms can be observed on all green parts of the plant. The symptoms are characterised by whitegrey dusty fungal growth, usually starting on the young green parts of vines (leaves and berries etc.). On exposed leaves, the mildew colonies are usually found on the lower surface, whilst it can be found on both sides of well shaded leaves. In South Africa, although the sexual phase (formation of cleistothecia to overwinter and releasing ascospores in spring) of the pathogen is present, it is believed that in most cases the primary infection every season originates from mycelia overwintering in dormant buds. The asexual phase of the pathogen can originate (as primary infection source) from either the individual ascospores that infect vines early in the season or from hyphae that at the end

TO PAGE 34

GROENTE & VRUGTE | NOVEMBER • DESEMBER 2020

GENERAL

Powdery mildew in grapes FROM PAGE 33

of the season overwinters in dormant buds. This is the characteristic grayish-white fungal growth commonly associated with the disease. In spring, the dormant hyphae that overwintered in the dormant buds, start infecting the new shoots and leaves as it grows. On the newly developing hyphae, structures called conidiophores develop and these produce conidia (or spores), which is the source of the secondary inoculum for the rest of the season. These conidia are distributed by air currents and do not require surface moisture to germinate but only requires sufficient air humidity. The hyphae penetrate the epidermis cells of the plant and forms a haustorium within almost every cell. This haustorium is a simple branched projection of hyphae that acts as a nutrition absorbing organ. The hyphae continue to grow and produce conidia that re-infect unaffected parts throughout the remainder of the season. The disease rarely kills its host, but rather parasitizes it for nutrients, resulting in significant yield losses. Apart from using the limited option to use resistant cultivars, the most common way to control disease is through chemicals. Originally sulphur was used to control the disease as a contact preventative measure. Systemic fungicides gradually replaced sulphur, and benomyl (a benzimidazole) became popular option for a while until widespread resistance was observed. Gradually this was again replaced with the sterol biosyn thesis inhibitor (SBI) type fungicides, also known as De-Methylation Inhibitors (DMI), which includes the triazole chemical group. The triazoles were used intensively to control the disease very successful in all the major grape production areas of the Western Cape. But as these fungicides have a very specific mode of action, resistance against the triazole group unfortunately also developed over time in all regions, specifically against triadimenol, penconazole and flusilazole. This led to the proposal of not using more than three sprays of DMI type fungicides in a season in order to slow resistance development. The arrival of the Quinone outside inhibitor (QoI) fungicides, such as azoxystrobin, allowed for more tools into managing fungicide resistance, allowing flexibility to alternate products with different MoA’s. Syngenta recently registered MIRAVIS™, a SC formulation with 200 g ADEPIDYN™ per liter formulated product. MIRAVIS is a broad-spectrum preventative fungicide for the control of foliar diseases on various crops, with only single active ingredient that allows for easier MRL management. ADEPIDYN or pydiflumetofen is a new carboxamide with a group 7 mode of action, belonging to the wider carboxamide family of active ingredients. SDHI’s inhibits the germination of the conidia of target pathogens by de-activating the Complex II SDH enzyme in the mitochondria of fungal pathogens, disabling respiration and thus suppressing the ability to generate energy. MIRAVIS is registered to control, amongst others, powdery mildew (Podosphaera leucotricha) and scab (Venturia inaequalis) on apples,

as well as powdery mildew (Uncinula necator) and botrytis rot (Botrytis cinerea) on grapes. Overall this product gives excellent control of powdery mildew and is highly effective against difficult to control diseases such as botrytis rot. ADEPIDYN exhibit a high intrinsic activity and this allows for high performance at low rates. It also exhibits excellent rain fastness due a rapid uptake and affinity of the leaf wax layer, creating a reservoir. ADEPIDYN exhibit longer lasting effective control due to the slow movement into the leaf tissue and the xylem over a period of 2-3 weeks. Although translaminar and xylem systemic properties of ADEPIDYN are limited, the molecule has significant biochemical potency and can therefore deliver disease control away from the point of application over a prolonged period. On grapes, MIRAVIS is positioned to be used in a preventative spray programme to control powdery mildew. The recommendation is to start applications at sprouting / three leaves unfolded (BBCH13) stage of vines, with a 10-14 day interval, using the shorter interval when higher disease pressure prevails. To assist with resistance management, MIRAVIS (or any other solo SDHI MoA Ai) applications should not exceed more than 33% of the total fungicide applications used in a programme in a season, with no more than two consecutive applications and not exceeding 3 in total MIRAVIS applications in a season. As ADEPIDYN possesses no cross resistance between triazoles (DMI) and strobilurine (QoI) chemistry, it is proposed to build a spray programme that alternates between these chemicals to assist in managing disease resistance development. Alternating between these chemicals is proposed in a responsible resistance management programme. The dose rate for powdery mildew control is 20-25 ml/100 L in a proposed application spray volume of 500 – 1000 L water/ha. Withholding period after last application both table and wine grapes are 7 days. READ THE PRODUCT LABEL FOR FULL DETAILS. MIRAVIS® contains Adepidyn™ (pydiflumetofen) (Reg. no. L10761, Act 36 of 1947) CAUTION. MIRAVIS® is a registered trademark of a Syngenta Group Company. Syngenta South Africa (Pty) Limited, Private Bag X60, Halfway House, 1685. Tel. (011) 541 4000. © Syngenta Ag, 2000. Copyright of this document is reserved. All unauthorised reproduction is forbidden. References: https://ohioline.osu.edu/factsheet/plpath-fru-37 https://www.wineland.co.za/a-south-african-perspective-of-powdery-mildewin-grapevines/ https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/uncinula-necator https://bsppjournals.onlinelibrary.wiley.com/doi/full/10.1046/j.13653059.2002.00694.x Resistance in Uncinula necator to Triazole Fungicides in South African Grapevines (F. Halleenl, G. Holzl and K.L. Pringle); 2000 An Overview of the Biology, Epidemiology and Control of Uncinula necator (Powdery Mildew) on Grapevine, with Reference to South Africa. (2001) F. Halleen and G. Holz; S. Afr. J. Enol. Vitic., Vol. 22, No.2, 2001.

NOVEMBER • DECEMBER 2020 | VEGETABLES & FRUIT

Mastering Melons Enza Zaden is excited to bring our internationally attained success with melons and seedless watermelon to South Africa.

Taste

Internal quality

This is what our varieties are known for. This characteristic is top priority in our selection criteria. Melons should not only be sweet, but flavourful too.

Firm and crisp flesh throughout the fruit is important for handling, shipping, processing and enjoying.

Eating quality

It starts with the right genetics to get produce to the consumer, fresh! Firmness throughout the fruit, thin yet strong skins and moderated ripening are key attributes of our melons.

The right balance of taste, sweetness, aroma and texture combined are vital characteristics of melon to ensure a pleasant eating experience.

Long shelf life

enzazaden.co.za

ALGEMEEN

Mastering melons Backed by experience, market knowledge, extensive research, development and breeding teams, Enza Zaden is determined to bring its global success in melon and watermelon to South Africa. “We are excited about the potential of our range of melons and watermelons,” says Johan Stassen, Crop Specialist for melon and watermelon at Enza Zaden South Africa.

INCE LAUNCHING ITS marketing and sales subsidiary in South Africa, Enza Zaden has introduced a fresh range of genetics in various crops into the market, including lettuce, cucumber, sweet pepper and butternut. And now, the international seed company aims to do the same with its melon assortment. The introduction of new genetics in the South African market comes at an opportune time. Market knowledge South Africans will benefit from the research and development Enza Zaden has put into their melon and watermelon portfolio. With increased demand for melon and seedless watermelon grown for both local and export consumption, consumers have access to a wider array of melon than ever before. The prepacked mixed packages of cut melon pieces make the product more accessible and convenient to consume. Consumer’s expectation pattern is rising; they are willing to pay more for quality, particularly when it comes to flavour. The importance of taste, eating quality and long-shelf life demanded by consumers in Northern Europe and the US are becoming the benchmark in other parts of the world. This creates opportunities for the range of melons and watermelons Enza Zaden has become known for internationally. “Enza Zaden melons could always be exemplified by distinct taste, sweetness and exceptional eating quality, which was embraced by markets looking for smaller, better tasting fruit that shipped well without compromising internal qualities. Locally, however, our range was too small for our market. Newer varieties are larger, with the same great taste, brix and even better internal qualities,” says Stassen. From South America to the world “We have an exciting new hybrid being introduced not only in South America, but many other countries, including South Africa,” says Hamza Moudrik, Portfolio Manager for melon at Enza Zaden. Moudrik explains how being close to the market is of fundamental importance to the company. “Being closer to the growers not only helped us improve our hybrids for better yield, easier harvestability and resistance, but also to help link growers to markets across the world. This is how our melons grown in South America are exported for consumption in Europe.” For melons to be accepted by consumers of North European countries, they need to meet tough requirements, of which taste and eating quality are most important. “Growers appreciate improved level of resistance to foliar diseases, vigour and yield, while shippers and retailers love the taste, eating quality and long shelf life of our genetics,” says Moudrik.

GROENTE & VRUGTE | NOVEMBER • DESEMBER 2020

“South African consumers and therefore retailers and processors demand produce that is not only sweet but tastes good and maintains its freshness. On this level, our range never disappoints,” says Stassen, emphasising that taste, quality and yield are the key traits of Enza Zaden melons. Watermelon – from zero to hero Roughly four years ago Enza Zaden had the opportunity to acquire a family owned company, with three generations’ experience in breeding vegetables including watermelon. “K&B Development LLC already had several seedless watermelon varieties but struggled to stock up on parental lines. Enza Zaden tested the triploid watermelons in countries across the world and the potential was quickly realised,” explains Ton van der Velden, who at the time handled the negotiations as Regional Sales Director North America to Enza Zaden. Negotiations soon resulted in the acquisition of K&B Development LLC in 2018. Father and daughter continue to take on the breeding responsibility of watermelon at Enza Zaden in California. With Enza Zaden’s resources and experience, parental lines could be stocked up quickly, which meant larger commercial quantities of seed could be produced. With an advantageous distribution partner along the USA East Coast, the company has gained rapid gains of market share in only three years. What makes these watermelons so great? “The quality, uniformity and performance. Growers consistently recorded highly competitive yields and excellent fruit quality even under adverse conditions. The latest commercial introduction is the Crackerjack and is on its way to become the market leader,” says Van der Velden. “We already grow seedless watermelon in South Africa that originates from the USA. Judging by the rate of success of our watermelons there, we are hopeful to achieve the same here,” says Johan Stassen. In recent weeks, in commercial trials of a seeded variety, Maristo demonstrated great speed. “Maristo has the potential to be one of the fastest maturing elongated crimson types at around 70 days from transplant,” says Stassen. The future The local team is intensifying their development effort of their entire melon range, including Galia and yellow-Canary types with resistance to leaf-miner, and Italian sutured types which focus on better eating quality, Stassen says. “We have a full assortment to choose from and many new varieties in the pipeline. There is no doubt our market can benefit from what Enza Zaden has to offer.”

Kry meer as net gewasbeskerming

Benevia

Insekbeheer aangedryf deur aktiewe bestanddeel

Dis ‘n uitdaging om konsekwent aan verbruikers se vraag na hoë gehalte en esteties aantreklike groente te voldoen. Deur Benevia® insekbeheer vroeg in die seisoen te gebruik, gee dit gewasse ‘n voorsprong tydens die mees kritiese stadium van plantontwikkeling. Benevia® bevat siaantraniliprool (antraniliese diamied) (Cyazypyr®) Reg. Nr. L10390 Wet Nr 36 van 1947, versigtig. FMC Chemicals (Edms) Bpk, Posbus 44, Postnet Menlyn, Waterkloof Glen, 0181, Republiek van Suid-Afrika. Tel: +27 12 003 2938. Benevia® en Cyazypyr® is handelsmerke van FMC Corporation of sy affiliate. Datum: 03/2020. TD 20/077R

GEBRUIK PLANTBESKERMINGSPRODUKTE MET VEILIGHEID EN VERANTWOORDELIKE SORG. VOLG AANWYSINGS OP ETIKET TEN ALLE TYE MET TOEDIENING VAN PLANTBESKERMINGSPRODUKTE.

ALGEMEEN

Urgent action needed to protect SA’s potato industry Since 2000/01 potatoes accounted for approximately 45% of total vegetable crops produced in South Africa and contribute around R8,5 billion to the economy. These numbers, however, are under threat due to a surplus of frozen and processed potato products in Europe, as a result of a decreased demand brought on by the COVID-19 pandemic worldwide and hence significantly depressed prices.

S SOUTH AFRICA IS a key destination for processed potato product exports from the EU where there is a history of dumping, this is set to have a negative impact on the country’s agricultural sector and surrounding communities. Cognisance must be taken that over and above the normal farm support that EU farmers receive, there was also special COVID-19 support measures afforded to potato producers. This support, combined with low priced surpluses, will drive export prices down further with a significant risk of increasing dumping margins threatening the South African potato industry. André Jooste, CEO of Potato South Africa (PSA), says that the local potato industry has already suffered significantly from a decrease in demand as a result of COVID-19 related regulations, such as the closure of restaurants and fast food outlets, restricted trade and movement of informal traders. “The result was a significant drop in prices far below break-even prices for producers and a build-up of stock levels in the processing sector. A further blow due to low priced imports from other countries could be catastrophic.” The Potato and Vegetable Processors Forum (PVPF), which includes PSA, McCain Foods South Africa, Natures Garden and Lamberts Bay Foods, have been lobbying the Government to institute a temporary prohibition on imports of frozen potato chips from the European Union as a consequence of market conditions impacted by COVID-19. This is to protect the sustainability of the potato industry, inclusive of employment by local potato growers and processors in the country. Potato growers and processors have significant economic multipliers for rural towns and cities. As an indication of the size of the markets and potential severity of a surge in low prices imports, the EU produced 52 million tons of potatoes in 2018, of which 73,7% is produced in only six countries. In 2019 it was responsible for 68% of global export trade (including intra-EU trade) of French fries. Volumes exported by the EU increased from 4,5 million tons in 2015 to 5,7 million tons in 2019, while exports are dominated mainly by two countries responsible for 81% of export trade. In comparison South Africa produces approximately 230 000 tons of French fries annually. The potential volumes available to be imported could have a detrimental effect on the local market for years to come. New Zealand, Australia and the United Stated share similar concerns. To this end, one of the points outlined in the Forum’s argument to Government states that the long-term effect on local processors could result in a significant shortage of

GROENTE & VRUGTE | NOVEMBER • DESEMBER 2020

Buyers and other decision-makers should think twice about where they're sourcing their potato product from.

product once European markets recover. This is, because when considering the time it takes to grow potatoes from seedlings to final product, a disruption in local supply could have a severe long term impact on the supply to downstream industries. Jooste pointed out that there is also no guarantee that the benefit of lower prices as a result of imports from Europe will be passed on to consumers. “In fact, a longer-term consequence is that consumers could face higher prices if South African growers and processors are forced out of business as a result of cheap imports on the back of COVID-19 inflicted reasons. “By raising concerns against the importation of these products, we have an opportunity to buy and support the local industry and help rebuild the South African economy in a time when it is more critical than ever before, especially if one considers the strong labor multiplier of the industry,” he added. For example, the leading processor of potatoes and vegetable products in the country supports in excess of 6 800 full time jobs and procures potatoes from more than 100 local farmers, who plant in excess of 4 500 hectares of potatoes annually. “It is therefore imperative that we prioritise our growers, our supply chain and the expansion of the local agricultural economy; especially if we are to combat the financial effects of the COVID-19 pandemic,” Jooste said. “As such, while we wait for an answer from Government, we appeal to buyers and other decision-makers to think twice about where they're sourcing their potato product from, to ensure they continue to support the local industry which so desperately needs to recover from the pandemic and keep operations afloat,” concluded Jooste.

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SumiPleo

Unieke chemie vir doeltreffende insekplaagbeheer

SumiPleo® word reeds wyd vertrou as effektiewe alternatiewe chemie vir weerstandsbestuur van Lepidoptera plae in S.A. Beheer van Afrika bolwurm, Aartappelmot en Tuta absoluta in aartappels, Afrika bolwurm en Tuta absoluta in tamaties, Ruitrugmot in Crucifereae soos kool, blomkool, broccoli, brusselse spruite asook Afrika bolwurm in blaarslaaisoorte is geregistreer. Registrasie vir die beheer van Herfskommandowurm (Spodoptera frugiperda), ’n indringerplaag op mielies en suikermielies is ook nou verkry. ’n Afname van Amerikaanse- en Ertjie Lyriomyza blaarmyners op aartappels en tamaties, asook vermindering van Tamatievalslandmeterwurms in tamaties kan ook na toedienning verwag word. VERSTANDIGE KEUSE Die kragtige werking van die aktiewe bestanddeel Piradaliel dichloropropeen derivaat bied talle uitstaande voordele: • Lae risiko vir soogdiere en voëls (Toksklas 3: Blouband). • Lae risiko vir operateurs. • Doeltreffend teen groter Lepidoptera larwes met lae risiko vir voordelige plaagvyande, asook bye en erdwurms. • Ideale produk vir gebruik in Geïntegreerde Plaagbeheer Programme (GPB, Eng.: IPM). • Aktief teen chemies weerstandige Lepidoptera spesies, veral as dit afgewissel word met alternatiewe produkte soos DiPel® DF en Florbac® WG met ander werkswyses. • Geen kruisweerstand met ander chemiese groepe is tans bekend nie. • SumiPleo® werk stadiger as peritroïedes maar vreetskade aan bespuite gewasse staak gou na bespuiting deur inhibisie van voeding. Vir meer inligting oor SumiPleo®, gesêls vandag nog met jou naaste Philagro-agent of produkbestuurder, Henk Terblanche - 082 829 4070. RAADPLEEG DIE ONDERSKEIE PRODUKETIKETTE VIR VOLLEDIGE GEBRUIKSAANWYSINGS & -BEPERKINGS SumiPleo® is die geregistreerde handelsmerk van Sumitomo Chemical Company, Japan. (Reg. nr. L8377, Wet nr. 36 van 1947) bevat piradaliel dichloropropeen derivaat, versigtig. DiPel® DF (Reg. nr. L6441, Wet nr. 36 van 1947) bevat Bacillus thuringiensis var. kurstaki, en Florbac® WG (Reg. nr. L 5531, Wet nr. 36 van 1947) bevat Bacillus thuringiensis var. aizawai. DiPel® en Florbac® is die geregistreerde handelsmerke van Valent BioSciences, VSA.

Philagro Suid-Afrika (Edms) Bpk l Reg. Nr.: 98/10658107 PostNet Suite #378, Privaatsak X025, Lynnwoodrif 0040 Pretoria: 012 348 8808 l Somerset Wes: 021 851 4163 www.philagro.co.za

P R O D U K T E W AT W E R K V A N M E N S E W AT O M G E E

ALGEMEEN

Digitalisation can reduce global food waste The scale of the global food waste problem is staggering. According to reports, 1,6 billion tons of food are lost or wasted every year, equating to a total value of $1,2 trillion being wiped from the supply chain. With one-third of the total amount of food produced globally being misused, the industry needs to look towards innovation and digitalisation to combat this ever-growing trend.

HROUGH EMBRACING TECHNOLOGY and digitalising the food supply chain, a move can be made towards reducing the amount of food waste and loss within the industry. Not only that, but it can also help ensure there’s enough resource to sustainably support the future global population. Although food waste is evident across the entire supply chain, the vast majority comes at the very beginning (during production) and at the very end (during consumption). The former of these is more common within developing countries, where the infrastructure is of a poor standard and cannot handle the food, thus creating waste, whilst the latter is more pronounced in developed countries with waste being caused by both retailers and consumers. According to the Boston Consultancy Group (BCG), the amount of food waste created in the supply chain is set to rise 1,9 per cent from 2015 to 2030. Utilising IoT in the supply chain Through having better levels of communication across the supply chain, the amount of food waste produced can be reduced. Each aspect of the supply chain must be in constant contact with one another to ensure our resources are managed efficiently. This is where the Internet of Things (IoT) can support and improve supply chain efficiencies. Based on having interconnected and interrelated systems and processes, IoT allows each aspect of the food industry to have access to key data around the supply, production and management of produce, which can help reduce the amount of waste created. Without the wider adoption of IoT in the food supply chain, the levels of food waste could increase by 50-90% as a result of several combined factors, such as the increase in food demand due to the ever-growing population. By allowing all stakeholders within the supply chain access to key data shared across integrated systems, processes can be optimised further along in the chain to maximise how the produce is handled. For example, a bad batch of apples with a high percentage of internal browning would require specific equipment set up and would need to be fine-tuned to ensure the maximum value can be extracted from the apples. It is believed having this connectivity could save the supply chain up to $60bn in waste. Through having this pre-warning of any information regarding a batch of produce, farmers can not only optimise their yields by reducing the risk of waste, but the other stake-

GROENTE & VRUGTE | NOVEMBER • DESEMBER 2020

holders can also plan accordingly to try and prevent the cause of waste. Having this ability to share data through IoT can also help reduce waste from a consumer standpoint. Retailers could use the real-time data in stores to showcase when the produce was harvested or picked and offer insights into the projected “sell by date”. This can educate consumers further on how long they have to eat the produce, thus helping reduce food waste through the implementation of technology. As well as utilising IoT, the supply chain can also use digitalisation to help improve the infrastructure it currently has in place. Cold chain plays a huge role in the food industry creating waste, mainly due to poor infrastructure. In India, for example, $14 bn is lost every year through poor cold chain facilities. However, implementing innovative and efficient systems can go a long way in addressing the food waste issue – particularly in developing markets. By deploying more advanced cold chain solutions within the emerging markets, which share the data across the supply chain through IoT, it could prevent large-scale food loss and waste. The conditions can also change in cold storage, and temperature affects many sorting technologies, so the ability to link cold storage sensors to packing equipment can enhance performance. The final step is to layer artificial intelligence to start to understand previously unseen patters and even more efficient ways of working. Going digital to fight food waste With the ever-rising statistics around food waste, now is the time for the industry to adopt a more digitalised approach across the supply chain. Implementing integrated and innovative systems will allow all key stakeholders – from field to fork – to efficiently manage food and reduce the risk of waste at loss. Digitalisation won’t just help from a sustainability aspect, but also help businesses drive their own profitability by improving processes and efficiencies. It becomes the answer to the pushpull paradox for commercial benefit and combating global food waste. At Tomra, they are committed to creating sensor-based sorting and grading systems to help the supply chain win the battle against food waste. Through their systems, they aim to help food businesses maximise yields and ensure any produce can be recovered and reused, increase productivity with high capacity sorting and provide consistent high-quality food assurance.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ INSECT COLUMN

Coconut bug

(Hemiptera: Coreidae) Coconut bug is indigenous in East Africa and was reported for the first time in South Africa during 1977. Kokosneutbesie and kokosneutstinkbesie are other common names of the coconut bug in South Africa. It is considered as a major pest in Eastern and Southern Africa and attacks various crops such as coconut, avocado, cashew nut, guava, macadamia, mango, cocoa, pecan, cinnamon and various leguminous crops. In the early 1990â&#x20AC;&#x2122;s, coconut bug became an important pest of avocados in South Africa, particularly because of its potential to cause damage to exportable fruit. Nozibusiso Maphumulo IPM-PROGRAM, NORTH-WEST UNIVERSITY POTCHEFSTROOM

e-mail:mashimanenozi03@gmail.com

Coconut bug classification: Class: Insecta (Insects) Order: Hemiptera (true bugs) Family: Coreidae Genus: Pseudotheraptus Species: Wayi

OCONUT BUG EGGS ARE smooth and oval in shape with a length of about 2 mm. They are creamy white to light-brown in colour when laid and change to a dark reddish-brown colour prior to hatching. Nymphs are redbrown to green-brown in colour with long antennae that is flattened from 1st to 3rd instar, as opposed to those of adults that are cylindrical. All nymphal stages are similar in morphology with nymphs being about 5 mm long and lacking wings. Adults of the coconut bug have a reddish brown colour on their back and are pale brown with pink spots on the underside. The tip of the wings is darker and their eyes are reddish in colour. Females are about 13-16 mm long while males are slightly shorter with a length of 12-14 mm. They have long cylindrical antennae that is equal to the length of their body and veined, leaf-like wings. Eggs are laid individually on the underside of mature leaflets of the host plant next to the base, but they can be occasionally laid on young fruits or flowers. The pre-oviposition period of the coconut bug is 9-13 days. Each female lays between 74-100 eggs. Eggs hatch after 6-8 days. Coconut bug have five growth stages (nymphal instars). The nymphal instars take about five weeks to become fully matured and reach adult stage. Adult males can survive for about 84 days while females can survive for about 73 days. They are strong fliers and fly quickly especially when disturbed. Adults do not like direct sunlight and heavy rain and are very active on cloudy days. The duration of the life cycle takes 31-48 days depending on climatic conditions. It has multiple generations and can complete nine or more generations per season. Feeding by both nymphs and adults cause damage to host

Coconut bug damage on avocado (https://www.avocado.co.za/wp-content/uploads/2019/12/SAAGA_Factsheet_-_Coconut_bug1.pdf).

Coconut bug adult (https://www.cabi.org/isc/datasheet/45033#toPictures)

plants as it results in wilting and necrosis of young stems, leaves, inflorescences and fruits as they suck sap and inject toxins into the host plants. Nymphs and adults feed on both young and mature avocado fruits. Feeding damage on avocado is noticeable by a lesion which is slightly darker than the rest of the fruit skin. As fruit matures, the lesions become sunken and dark brown to black in colour like hail marks. The lesion develops into a typical hard clot inside the avocado fruit. An integrated approach is recommended to successfully manage the coconut bug. Although certain insecticides do control this pest, biological control through the use of natural predators and parasitoids can also be used.

NOVEMBER â&#x20AC;˘ DECEMBER 2020 | VEGETABLES & FRUIT

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