Undercover Farming Magazine Nov/Dec 2018 by Undercover Farming Magazine

Undercover

farming

ucf

NOVEMBER - DECEMBER 2018 Volume 15 No 6

I  I R40.00

The original source and the end product, auxin which improves root growth and fruit quality

KELP PRODUCT

produce

PEST MANAGEMENT

CUCUMBERS

Kelp Product for Root & Fruit Improvement Page 4

Application of Calcium Page 7

Prevent Powdery Mildew Page 13

Growing Cucumbers Profitably Page 10

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MAIN ARTICLE

PROPRIETOR I ADVERTISING SUZANNE OOSTHUIZEN 012-543 0880 I 082 832 1604 suzanne@axxess.co.za EDITORIAL CONTENT & COMPILATION Johan Swiegers 082 882 7023 editors@axxess.co.za ADDRESS PO Box 759, Montana Park 0159 E-MAIL magazine@axxess.co.za FAX 086 518 3430 ADDRESS PO Box 759, Montana Park 0159 DESIGN Fréda Prinsloo PRINTING Business Print Centre DISCLAIMER Undercover Farming accepts no responsibility for claims made in advertisements or for opinions and recommendations expressed by individuals or any other body or organisation in articles published in Undercover Farming. COPYRIGHT Copyright is reserved and the content may only be reproduced with the consent of the Editor. Subscription Online subs: Email to suzanne@axxess.co.za If you subscribe on-line, e-mail your deposit and address details to: magazine@axxess.co.za. More information from Suzannne Oosthuizen: 012-543 0880. Subscription form available on inside back page. visit us at I besoek ons by

A CHRISTMAS SCRIPTURE

Luke 2:7 KJV 1611 “And she brought forth her first born son, and wrapped him in swaddling clothes and laid Him in a manger, because there was no room for them in the inn.” Verse 16: “And they (shepherds) came with haste, and found Mary and Joseph, and the babe in a manger.”

Contents 4 Kelp turned into farm produce enhancer 7 Supply Calcium via the roots 7 Hytech Agriculture serves the greenhouse industry 8 Could protected cropping supercharge agriculture? 10 Cucumber production in the greenhouse: follow the

FRONT page: Kelp – marine-based product increases root growth and fruitset.

INSIDE ...

rules to be commercially viable

13 Preventing powdery mildew in your greenhouse 13 Jaco Boer R.I.P. 14 Coping with physiological disorders in lettuce 14 Handling excess flowers at Royal Flora Holland 16 Apples, deciduous fruit undercover in Lesotho 16 Co-creating water re-use and efficiency for

18 Integrated pest management in the greenhouse 19 Time to invest in aquaponics

industries in SA

We wish all our readers, advertisers, correspondents and all involved in the publishing of Undercover Farming a Blessed and Peaceful Christmas Season and Prosperous 2019!

ooking back over fifteen years of involvement with greenhouse and shade net production, the magnificent jump in technology is quite amazing. Undercover Farming magazine was started during the years an organisation called AVUP (Association for Vegetables Under Protection) still existed and offered annual meetings in Stellenbosch. Under new leadership it changed to IASA (Intensive Agriculture S.A.) to be more appropriate to all undercover farming operations. Sadly soon the organisation was disbanded. That is why Undercover Farming started to hold conferences in the north and south in order to annually bring producers old and new and suppliers and other role players together. Still, during all the some sixty or more years of undercover farming in South Africa, nobody is able to within 100 ha, provide actual statistics of our industry. Therefore we are not recognised for what we really are accountable for in terms of our total input to the GDP of an important sector of agriculture in SA. Although rumour have it that we stagnated because of various current internal situations, fact is, exports to other countries becomes better by the day. And if one talk to individual farmers you hear how they grow their businesses. Is there a lack of communication or is it because no statistics are available on how we shape? Suppliers are talking about their achievements in Kenya and other mid African countries; it was even said ‘because they are closer to the market’! How close is Johannesburg from Rome, Paris, Athens, Frankfurt or Amsterdam? What is interesting is the fact that 130 countries are able to report their statistics. The total global area which is covered by greenhouses has increased substantially over the past twenty years. An estimate by one Hickman shows the global area has increased from 0.7 million ha in the 1990’s to 3.7 million ha in 2010. Much of this increase can be attributed to a rapid expansion of plastic covered greenhouses. China, Spain, South Korea, Japan and Turkey have a combined cumulative greenhouse covered area amounting to 96% of the globaltotal greenhouse coverage and that does not include the UAE where maxi greenhouses are being constructed of late. In conclusion, this surely points to the fact that more people of different backgrounds are changing their dietary habits to fresh produce to a large extent. Undercover farming in SA must come alive and the officials must recognise our importance in their future food security planning. It is that time of the year again where we wish all our readers, farmers and suppliers a sincere Blessed Christmas and look forward to a prosperous 2019!

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Kelp turned into farm produce enhancer

Kobus Lindeque, CEO Afrikelp (Pty) Ltd

After the harvest. An Afrikelp boat comes ashore at Kleinbaai slipway with its load of kelp. The new inflated rubberised boat of the company can harvest ten tons of kelp at a time.

Gansbaai, internationally acclaimed to be the foremost place on earth for cage diving to view sharks also offers excellent whale watching opportunities. Tourists to South Africa put this spot on earth high on their ‘must experience’ agenda.

ut Gansbaai also offers a unique product which is harvested from its waters around Danger Point (the historical site where the famous HMS Birkenhead sank in 1852) – kelp (Ecklonia maxima), a giant brown seaweed species which grows in abundance along this part of the coastline. This is a truly South African product. Kelp leaves are harvested under strict control of the company, Afrikelp (member of Ascendis Biosciences in co-operation with DAFF, marine conservation and development agencies. Undercover Farming’s editor was invited by Chris Strauss, financial manager of the company to visit the plant at Gansbaai. The Managing Director of the company is Kobus Lindeque, a well-known personality in the agricultural bio-sciences arena. The origin of the company hails from Namibia and the founder in 1971 was the late Klaus Rotmann who grew kelp and did algae extraction at Swakopmund and Luderitz Bay. An early morning stop was at Kleinbaai, better known as Van Dyksbaai where a slipway into the sea is built and maintained by marine conservation and the local fishing industry. This is also the spot from where whale and shark watchers leave. The three large inflated rubberised boats landed with their loads of kelp and a truck stood by

to load. From here it is a mere stone’s throw to the plant in the industrial area of Gansbaai proper where around fifty local employees work (including the harvesters). This is where the action begins. Loads of kelp leaves(fronds) (they are carefully cut 10cm from the bubble at the top of the stalk to induce re-growth) are selected and fed into a pulp grinder. Some stems are also fed into a separate grinder specifically designed for stalks. Only stalks found without bubbles that were damaged by boats or natural causes are cut for harvesting purposes. All kelp is cut in a strict rotational pattern and each boat carries a tracking device and is monitored to harvest areas in a predetermined pattern for conservation reasons. This

harvesting process and the health of the kelp forests are monitored by both DAFF and Sea Fisheries Research Institute. Dry kelp stems are also gathered along the coast. These are ground, compacted and exported to China where extracts are used to manufacture paints, toothpaste and other industrial products. The liquid kelp processing started in 2002 in little more than a garage space. From these humble beginnings it was projected to become a major agricultural consumer item and as trials proved its success demand escalated to where it is now in high demand by foremost fresh food producers as well as citrus and nut producers. This original family business was purchased in 2016 by Ascendis

Kelp contains a high amount of auxin which is minimally found in vegetable plants. The Afrikelp product increases therefore root growth and quality of fruit.

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The freshly harvested kelp is inspected carefully by a quality control assistant at the Gansbaai plant. At the laboratory in Dresden of Ascendis Biosciences Plant Sciences department, the Afrikelp product is carefully monitored and tested with control plants to verify its unique performance.

A worker presses the kelp leaves with the aid of a kelp stem into the grinder that eventually squeezes out the liquid.

The liquidised kelp is stored in these tanks at the Gansbaai plant before it is pumped in containers.

The final product. Afrikelp’s agricultural product is offered in three sizes of containers to make it viable for the different sized farms.

Health, a diversified people, plant, animal health company. Afrikelp is the company’s biological arm. At the Gansbaai plant all fresh kelp plant material is checked before entering the cold micronisation process (cmp). The cell walls of the kelp are mechanically cut without heat or chemicals releasing cytoplasm or, predominantly auxin – this refining process takes eight hours during which it is filtered through a food industry filter allowing no solid particles over

30 micron through to the liquid. The concentrate is then sent for testing of its bio-stimulant hormone levels to the University of Dresden, Germany. In Dresden, Germany at the plant sciences department, agricultural plants are researched to find out how plant hormones develop and how auxin regulates the plant growth stages. Auxin (Greek for ‘grow’) is one of the molecules in a plant that plays a role in the growth and development of a plant. It regulates its shoot and root growth. As we know; a better root system takes up water and nutrients more efficiently from grow medium. The concentrate derived from kelp is tested for its properties of auxin to stimulate plant growth and development as well as storage of auxin in the plant. Back in Cape Town at the SA Head Office in Montague Gardens, the tested concentrate is blended to ensure constant hormone levels of bio-stimulants in each batch will be as prescribed. The product is then blended according to the customer’s requirements for his farm and packaged according to the customer requirements in either 25l drums or 1000l bins. The average plant has a certain percentage of auxin but as soon as auxin is added through foliar application, an imbalance in the internal plant hormone levels occur. However, the auxin travels down to the roots and proliferate the root system; cytokinin is formed at the tips of the roots which return the plant’s balance and enables the plant to take up more nutrients and thus stimulates top growth within seven days and eventually a higher yield. There are two forms of auxin; an active and inactive form. The active form has an immediate effect on plants. This is the product received by the producer that he can trust and expect a predictable increased yield. The concentrates have

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an extra benefit to the producer; plants introduced to this product also withstand certain diseases, withstand drought, increase nutrient uptake and offers longer shelf life according to Afrikelp. The company executes trials globally on many types of crop and the Afrikelp product is by now proven for its success. Farmers use between 2 and 21 litres of Afrikelp per hectare per season depending on crop, soil location and weather. Results on table grapes in SA showed that Afrikelp’s product increased the sugar (brix) content by more than 34% over standard practices. The bunch weight increased by 36% on average this resulted in an overall improved quality of the grapes. A spokesperson for ZZ2 said they have been using Afrikelp on their tomato crops for the past six years and it fits in well with their program. They have a fixed program of spraying with the product and improved both on yield and shelf life. In a trial carried out with a major tomato producer, a test area of 41.38 ha and a control area of 130 ha was planted with the same cultivar. From the control area 90 tons/ha were received (12% first grade, 30% second grade and 58% third grade. But the results in actual treated figures were much different; 123 tons/ha was picked, 24% first grade, 40% second grade and a mere 36% third grade. This means by using the kelp based product, fifty percent higher income was received. Results like the aforementioned are experienced by producers across the board. The only conditions to receiving such results are; keep to the correct dosage, do not under-dose and at least spray two but preferably three times. The product is a natural organic extract from seaweed (kelp) and assists the plant to take up water, fertilizer and trace elements more efficiently by increasing the quality of the crop and the size of the harvest. J.S.

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Supply Calcium via the roots Calcium (Ca) is the only nutrient that is totally phloem immobile, it moves in the xylem with the transpiration stream, also driven by root pressure. Ca binds with polysaccharides to strengthen cell walls, producing firm plant tissue and good fruit quality.

ymptoms of Ca-deficiency develop due to the collapse of cell walls, followed by a dark discoloration. Too much Ca, on the other hand, may stiffen cell walls that may induce fruit cracking. In order to manage the uptake and translocation of calcium (Ca), the following should be taken into account:

Ca-uptake Conditions that suppress the uptake of water also limit the uptake of Ca, illustrating the need for sound fertigation practices. Cell walls in roots suberize with age, making it impermeable for the large Ca ion, explaining why Ca uptake is confined to young root tips only. Young root tips can be damaged at high salt concentrations that may develop between irrigations. Since high EC levels also restrict the uptake of water (and

Ca), an EC increase from drip to drain should not be more than 50%. If so, increase the irrigation frequency or pulse volume or lower the EC of the applied solution. Low Ca levels in nutrient solutions will invariably lead to Ca deficiencies. However, the ratios between the cations in solution are also extremely important. High levels of ammonium (NH4), potassium and magnesium suppress the uptake of Ca, especially in summer with hot root media. Ammonium is the strongest Ca suppressor. Peppers are extremely sensitive to high ammonium levels, since blossom-end-rot (BER) can develop on the fruit with as little as 0.5 mmolc NH4 L-1 in the nutrient solution (7 mg/kg NH4-N). With NH4 at 1.0 mmolc L-1, as recommended for tomatoes, the incidence of BER on

peppers may be as high as 60%. Most growers do not realize that commercial calcium nitrate (distributed by most of the big fertilizer companies) contains 1.7% ammonium. By using this calcium source at normal levels, NH4 will be applied at about 0.75 mmolc L-1. The recommended NH4 level in a pepper nutrient solution is only 0.3 mmolc NH4 L-1.

Insufficient water movement to low transpiring tissues On hot days or low relative humidity conditions, water mainly moves from roots to leaves for evaporative cooling, carrying Ca to the end of the

HYTECH AGRICULTURE SERVES THE GREENHOUSE INDUSTRY Floris Conradie started Hytech Agriculture with the late Jaco Boer in 2008. Floris, formerly in marketing, logistics and administration in the business, now took over reigns from his former partner. The address remains in Krugersdorp, Gauteng and trade will continue as before.

ytech Agriculture became known countrywide for its turn-key greenhouse projects, irrigation systems installation and maintenance, spray carts, and other services to the industry. According to Floris he has just completed a project and look forward to 2019 which indicates to Floris Conradie, be a good year for them. “We have been Director; Hytech praised by our clients for our excellent Agriculture. and prompt service and our intensions are to carry on the good work, serving this growing industry not only in South Africa but also in our neighbouring states,” Floris said. “At this time of the year, and looking back over the years in business, we wish to thank our loyal clients for their support and assure them of our continued excellent service.” Floris Conradie, now the new owner of Hytech Agriculture, thanked his late partner, Jaco Boer for the opportunity to have built up together a new enterprise servicing the greenhouse industry and made it clear that the foundations laid by Jaco will be built on in future.

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transpiration stream where it accumulates to form hard and brittle leaves. Concurrently, movement of water (and Ca) to low transpiring organs decrease, where cell walls may then collapse. Where plant organs are permanently wilted or permanently turgid, a lack of diurnal fluxes restricts movement of Ca-rich xylem sap into the organs. Root pressure should be used to force Ca-rich water into moderately wilted organs each night to prevent calcium deficiencies. The last irrigation must provide a moist and Ca-rich root medium at night. In a trial, the incidence of BER on peppers decreased when high nutrient solution temperatures were reduced in a water culture system. The oxygen

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content of the water increased at lower temperatures, improving water (and Ca) uptake. Substrates should thus be well aerated to avoid water logging.

Insufficient functional Ca Once fixed to plant tissue, Ca can not be moved to other organs. Ca is also used to neutralize organic acids, produced at high respiration rates, forming insoluble Ca-salts such as Ca-oxalate. To prevent this loss of functional Ca, high respiration rates should be lowered in mid summer by shading, to reduce radiation and plant temperatures.

Foliar Ca-applications? Micronutrients may be applied with foliar sprays since small quantities are needed,

easily absorbed by leaves. Being a macro nutrient, large quantities of Ca is needed. Ca is the biggest macro nutrient cation and can only enter via young plant tissue. Only a very small percentage of foliar applied Ca is absorbed, but it can not be moved from the leaves to developing fruit. Ca has no reverse gear, it moves via the transpiration steam in one way only. Avoid Ca foliar sprays; rather manage the interacting factors discussed in the three scenarios above. This is an extract from the book: ‘Nutrient solutions and Greenhouse management’ only distributed by the Combrink family trust: Web page: http:// www.greenhousehydroponics.co.za E-mail: njjc@sun.ac.za

Could protected cropping supercharge agriculture? South Africa’s greenhouse and shade net farming industry being in the Southern hemisphere, experiences similar climatic conditions as our friends ‘down under’.

‘S

ustainable growth’ is the key phrase underpinning the Australian Government’s plans to make the nation’s agricultural industry a $100 billion industry by 2030. Yet with widespread and continued drought conditions challenging these ambitious plans, growers are looking to new solutions to ensure more consistent crops and higher yields – and protected cropping is one increasingly attractive proposition. There is no doubt that indoor and controlled environments, speed breeding and hydroponics systems are currently driving food production like never before. The Protected Cropping Industry is the fastest growing food producing sector in Australia, valued at around $1.8 billion per annum. As Vertical Farming Systems Executive Director, John Leslie explains, that’s no surprise. “Australian agriculture currently has a return on investment of about 3-5%, and that’s not sufficient to attract investment into the sector. Vertical farming removes much of the labour cost, which is the most expensive component of farming, so the ROI can be increased to 20% and upwards – and then agriculture does become an attractive investment proposition.” With a $3.9 billion fund recently set up to support water infrastructure and drought-related projects, protected cropping has never been more relevant. Controlled environment farming protects the industry from unfavourable weather conditions like drought, contributing to

more consistent crops and higher yields. John sees vertical farming as the ideal solution for some parts of the industry, because the process is impervious to climate, and the dehumidification process generates a massive amount of water. “We’re actually producing water out of the air, and that makes vertical farming highly viable, even in places as arid as the Sahara desert. While vertical farming isn’t a fix-all for every drought situation, it’s another tool we can use to combat the effects – and it will certainly support some parts of the food supply chain and help address things like drought,” he said. Hydroponics is another production sector currently experiencing rapid growth – and as hydroponics grower and consultant Brian Ellis explains, it’s highly efficient in its use of inputs including water, fertilisers, labour, land and energy. “It’s possible to produce 5-10 times as much per hectare using hydroponic systems compared to growing in soil. There’s no doubt that adverse weather is impacting everyone as the climate continues to change – but with hydroponics you have much more control over your environment. Essentially there are much more predictability, and less effect from extreme weather,” he said. Brian explains how hydroponic systems use only minimal water, which contributes further to their viability. “We often only use as little as 5% of the water for re-circulated hydroponic crops, compared to growing the same crop out in the field. That gap may have

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closed a little with the introduction of new technologies, but it’s still nowhere close to that figure. As drought continues to affect growers, there’s no doubt that hydroponics will become even more important, and more relevant to the success of the industry,” he said. In the face of food security and global climatic variability concerns, safe, sustainable protected cropping in the form of vertical farming, hydroponics and speed breeding could well be the way of the future. The Global Forum for Innovations in Agriculture (GFIA) presented the latest innovations and technologies for the controlled environment and protected cropping sector at Australia’s largest agricultural innovation event, GFIA in Focus, in Brisbane on November 27-28. John and Brian joined a host of guest speakers that discussed everything from vertical farms and greenhouses to hydroponics and aquaponic systems. In South Africa our undercover farmers are not supported by government financially and we sincerely hope that the powers to be will soon take note of countries like Australia and others in the southern hemisphere that are seeking better outcomes for food production in an ever drier climate by investing in this industry at large. Whether we will want to know it or not, if the drier climate increase as fast as it is foretold, our food intake will change to more greens and healthier eating – and protected cover farming will have to expand rapidly in the country to supply in future demands (ed.).

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ADVANCING BEYOND THE BASICS Known today as “the all-in-one seed distributor”, Klein Karoo Seed Marketing (K2) has evolved to become a leading independent African seed company that offers a wide range of quality seed to growers across the continent. K2’s current focus is mainly on the South African and SADC territories with local operations in South Africa, Zambia and Zimbabwe. Through its owners, Zaad, who also have interests in several international seed companies (operating in over 60 countries), K2 is well connected globally.

With an ever-increasing global population, there is most certainly a growing demand for food. As a supplier of inputs into the food production sector, we believe this to be an exciting sector with enormous opportunities for both ourselves and our clients. Success however, is in the details and at Nuvance we continually invest in research to remain abreast of the latest trends and challenges, in order to remain relevant and competitive. To achieve this, we recently commenced trials inside our new 5,000m2 state-of-the-art greenhouse complex. This modern facility (along with a As we continually strive to advance the business, we are trial farm near Brits) allows us to identify and continually proud to introduce to you Nuvance (Pty) Ltd. Nuvance is a introduce new varieties, ensuring that we remain relevant wholly-owned subsidiary of K2 and intends to bring its clients through providing the best possible vegetable varieties to you the latest advancements in the industry. Nuvance will have - our clients. Just one of the ways Nuvance is committed to go a distinct focus on the supply of high-quality vegetable seed, “beyond vegetable seed”. professional services and support to growers to benefit both our existing and future customers. Nuvance is blessed to have The challenges faced by the agricultural industry also seem incredibly knowledgeable employees with a passion for what to continually increase and Nuvance intends to work together they do – “proudly from Africa for Africa”. We are committed with its growers to ensure that we make a positive difference to passionate alliances through service excellence and a deep on the farm. We would also like to believe that our growers, through faith, don’t allow insecurity to cloud their resolve. knowledge of business in agriculture. One thing always rings true – when we have hope, we have Mutually beneficial relationships with our stakeholders are everything. For those in pursuit of success with vegetables, vital to our existence. Solid relationships with our suppliers Nuvance is the locally owned vegetable seed distributor that also afford Nuvance the opportunity to present our clients offers service excellence, a wide range of relevant and quality with a comprehensive product range. Nuvance will be the vegetable seed and customised solutions. Nuvance, as part sole distributor of vegetable seed from Bejo Zaden, De of K2, is driven by the desire to celebrate shared successes Groot en Slot and selected Seminis varieties in South Africa with our clients and our team of trusted advisers are looking and selected territories. With Nuvance’s seed- and service forward to being of service. offering, we would like to contribute towards the sustainability of our clients who in turn play an integral part in reaching the Nuvance – beyond vegetable seed! goal of food security.

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Cucumber production in the greenhouse: follow the rules to be commercially viable

With growing popularity of greens on the table, greenhouse cucumber production is very popular in many areas of the world. The cucumber is a warm season crop with required growing conditions of 27°C to 39°C and plenty of sunlight.

raditionally the primary type of cucumber grown in greenhouses is the standard European seedless type. The fruits are mild in flavour, seedless, and have a thin edible skin that requires no peeling. Harvested fruit generally range from 30 to 35 cm in length and weigh about 0.45 kg each. However, more recently smaller fruits of mini cucumbers have become more popular and commercial production has increased. Cucumbers and other vine crops are monoecious. Monoecious plants have separate male and female flowers on the same plant. Male and female flowers are similar in appearance. However, the female flowers have small, immature fruits at their base. Pollen is transferred from the male to the female flowers by bees and other pollinators. When properly pollinated and fertilized, the female flowers develop into fruit. The first flowers to appear on cucumbers and other vine crops are usually male. Female flowers appear shortly thereafter. Gynoecious varieties are special hybrids which produce predominantly female flowers. Seeds of a standard monoecious variety are commonly included in the seed packet to ensure

adequate pollination. (The seeds of the monoecious variety may be dyed or placed in a separate packet.) Gynoecious varieties often outproduce standard varieties when a pollenizer (monoecious variety) is present. It is therefore essential to prevent bees and other pollinators from entering the greenhouse and carrying pollen from outdoor gardens or field cucumber plantings. Cucumber plants are indeterminate in growth, continually producing fruit on new growth, similar to greenhouse tomatoes. Greenhouse cucumbers are more sensitive to low

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temperatures than tomatoes. Minimum temperatures should be no lower than 18°C for sustained maximum production. Prolonged temperatures above 35°C should also be avoided as fruit production and quality are reduced at extremely high temperatures. Several different types of production systems and substrates can be used to grow greenhouse cucumbers. Possible production systems include open nutrient film technique (NFT), trough, bag culture, upright container, and rockwool. Soilless media commonly used include perlite, cocopeat, composted pine bark, peat mixes, and rockwool. Greenhouse cucumbers are ordinarily established in the greenhouse as transplants using a soilless peat-based germinating mix, rockwool, or foam blocks. Seed costs are very high; a typical cost is 50–70 cents per seed for currently recommended cultivars. Germination is generally close to 100%, so one seed per transplant container is sufficient. Producers may choose to over-plant the number of containers by 10% to 15% to make up for those few seeds that do not germinate and those plants lost during or shortly after transplanting. Some growers have successfully direct seeded cucumber into soilless media, such as perlite, cocopeat or composted pine bark, and at the same time seeded a few transplants to use as replacement plants. Transplant production should be confined to a small transplant production area of the greenhouse or a separate greenhouse entirely to make efficient use of space and energy and to assist in sanitation practices for disease control. Cucumber seed germinates rapidly (2 to 3 days) at an optimum germinating temperature of 29°C in the germination room. Once the seed has germinated, the temperature should be lowered to 25°C. During the seeding and transplant production stage, the plants must never become stressed for water or nutrients. A plant with three or four true 11

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leaves is ready to be transplanted. The transplants should maintain an upright growth habit (no curves in the stem) to aid in successful transplanting.

Selecting Cultivars There are many cultivars available for greenhouse cucumber production. The cultivars available are generally produced by European seed companies; however, several international companies have offices with trial plots and sales and technical support representatives in South Africa. Cultivars may change often and, as a result, growers should consult current recommendations through local seeds suppliers and industry representatives. Several factors should be considered when selecting a cultivar, including disease resistance, plant vigour, early and total yields, fruit size, colour and general fruit quality. Disease resistance is an especially important factor when selecting a cultivar. Diseases can be severe in greenhouses, and fungicide options are limited in the greenhouse. Diseases that can be problems in greenhouse cucumbers include grey mould, downy mildew, powdery mildew, cucumber mosaic, watermelon mosaic, and Pythium root rot in NFT. Growers must determine the levels of resistance or tolerance in the cultivars considered for production. Selection of a resistant cultivar may be the only practical method of control for some diseases.

Spacing Greenhouse cucumber plants have very large leaves, grow vigorously, and require large amounts of sunlight. Under good sunlight conditions, each plant should be provided around 0.5mÂ˛ of greenhouse space. Exact spacing between rows and between plants within a row will depend upon the type of training and production system to be used. Several training systems exist for greenhouse cucumber. The basic principle in developing a training system is to uniformly maximize the leaf interception of sunlight throughout the house. The selection of a system will largely depend on the greenhouse facility, the production system, and grower preference. A vertical system trains plants vertically to an overhead wire. Once the plants reach the wire they are topped and then pruned using an umbrella system. Single, evenly spaced rows can be used; however, double-row production is very popular. Typical spacing for this double-row system would be approximately 150 to 180cm between the centres of each pair of rows. The distance between the two rows within a pair is approximately 60cm. The spacing of plants in the row for such a double-row system would be 45 to 50cm. Single, evenly spaced rows in a vertical system would be approximately 150 to 180cm between rows and 30 to 45cm between plants within the row.

Pruning The most common pruning system for vertical trained plants is known as the umbrella system. In this system, all lateral branches are pruned out as they appear until the main stem reaches the overhead wire. The growing point of the main stem is removed when one or two leaves have developed above the wire. Two lateral branches near the top of the plant are allowed to grow and are trained over the overhead wire resulting in these two branches growing downward. The growing point of each lateral is removed when nearly to the ground. Fruits are developed at the node of each leaf. The fruits on the base, 75cm of the main stem should be pruned off as soon as they appear. This allows the plant to grow vigorously and produce early vegetative growth that is essential for maximum fruit production. 12

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Fruits above the basal 60-75cm of the main stem are then allowed to develop. The productivity of the laterals is generally less than the main stem. It is usually best to thin multiple-fruit clusters to a single fruit; however, vigorous plants can sometimes mature more than one cucumber at a node. Miniature and beitalpha types will support several fruit per node and must not be pruned to single fruit. Any distorted fruit should be removed immediately. The greatest growth of the fruit occurs between day 6 and 14 after the bloom opens (anthesis). Maximum fruit length occurs at day 14 followed by diameter increase. The shape of the fruit is somewhat tapered, being largest at the stem end prior to day 10 after bloom; however, the fruit becomes uniformly cylindrical by day 14. During the spring season, commercially acceptable fruit size is usually reached by the 11th day after the bloom opens.

Nutrient Programs Greenhouse seedless cucumbers have a high nutrient requirement and grow very rapidly when supplied with sufficient nutrients. As a result, growers must plan for an optimum nutrient program, making adjustments in the program as the crop demands change. The greatest demand for nutrients is during the peak fruit production period. Nitrogen and potassium are required in the greatest amounts; however, a complete nutrition program including essential minor elements is required. Designing a fertilizing program varies depending on the production system desired. Extreme caution must be used when interpreting or comparing research or articles from one production system to another. In soilless growing systems, a complete nutrient solution is used to supply the needed nutrients to the crop. Soilless culture increases the grower’s ability to control the growth of the plant, but it also requires management to achieve success. Many of the guidelines for soilless culture of tomatoes also apply to cucumbers. One concern of the soilless system grower is the supply of micronutrients or trace elements (those needed only in trace amounts). Soilless growers not only must supply their crop with the six macronutrients (nitrogen, phosphorus, potassium, calcium, magnesium, and sulphur), but also the 7 micronutrients (iron, manganese, copper, zinc, molybdenum, boron, and chlorine). It is especially important in a soilless system to test the source of water prior to developing a nutrient program. The

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raw water may have some amounts of many of the essential plant nutrients. These may need to be considered when developing a fertilizing program. The pH of the water is also critical and may need to be adjusted. Frequently groundwater in some areas has a high pH of 7.0 or above. The target pH of the nutrient solution supplied to the plants should be between 5.5 and 6.0. Generally nitric, sulphuric, or phosphoric acid is recommended for pH control. If it is necessary to raise the pH, potassium hydroxide is usually used. If the source water is alkaline due to high bicarbonate concentrations, the pH should be adjusted before the fertilizer salts are added to prevent precipitation. Plant tissue testing can be a useful tool in addition to a good soil testing or nutrient solution program to monitor the fertility. Cucumber roots have a greater oxygen requirement when compared with roots of tomatoes. Cucumbers develop a large root system in the growing tubes and as a result may become stressed for oxygen. Because of this concern, measures may need to be taken to provide improved oxygen supplies to the root zone. Continuous aeration of the nutrient solution and increasing the slope of the tubes to 2 feet or more in height for every 30 feet in length are reported to help. High solution temperatures also reduce the amount of dissolved oxygen in the solution. Growers must avoid high temperatures in the solution. Managing pests, the different potential diseases, insects, and nematodes is of essence in producing greenhouse cucumbers. Cultivar selection, greenhouse sanitation, and well-timed applications of properly selected pesticides are all important in managing these pests in the greenhouse.

Harvesting Fruits are harvested when uniform length, shape, and diameter are reached and before any yellowing appears on the blossom end. Typical fruit length in a standard European cucumber is 30–35cm but local retail chains may demand a specific standard of length. Frequent harvests are required because the fruits quickly become over-mature. Fruits are harvested as soon as they are marketable to avoid retarding the development of any younger fruit on the plant. Continued, timely harvest keeps the plants in a productive mode since cucumber plants have a limit to the number of fruits they can support at any instance. Growers harvest by either clipping the fruit stem or twisting the stem.

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The twisting method appears to reduce the amount of exuding sap through the stem. Harvest is usually required three or four times per week. Total expected yield will depend directly on length of harvest period. Yields range from half to one and a half kilograms of fruit per plant per week during the peak harvest period. A normal harvest period of 12 weeks in a well-managed crop can yield a total of 10 to 12kgs of fruit per plant. Most cultivar trials show similar but somewhat lower yields from mini cucumbers when compared to standard European cucumbers.

Packing and Storage European greenhouse cucumbers have a very thin skin resulting in high susceptibility to water loss and softening of harvested fruit. Immediately after harvest, containers should be covered to avoid exposure to direct sunlight. Each fruit is individually wrapped in a shrinkwrap film before packaging. Shrinkwrapping will minimize moisture loss and extend shelf life by several days. Since each cucumber has to be shrinkwrapped, this crop is very labour intensive and time consuming. Growers often mention they were not aware of the considerable time needed to properly shrink-wrap greenhouse cucumbers. Growers should invest in a commercial shrink-wrapping machine designed for cucumbers so that the shrink wrapping is done in a professional manner. There are several types and sizes of shrink wrapping machines available to meet the needs of all sizes of growers. Mini cucumbers are much less susceptible to water loss and do not require shrinkwrapping. Fruits of mini cucumbers are normally bulk packed in small- to medium-sized waxed boxes appropriate for the target market. The harvested fruit should be cooled after harvest to minimize water loss. Optimum fruit holding conditions are approximately 13°C and 95% relative humidity. Cucumbers are also sensitive to ethylene gas. When cucumber fruits are exposed to ethylene, they lose chlorophyll and rapidly become yellow. Exposure to levels of 1 ppm ethylene for 1 day at 15°C will result in a noticeable yellowing of the fruit. Chilling injury to cucumber fruit, even for a short duration, will increase the production of ethylene by the fruit. It is very important that cucumbers not be held or shipped in the same compartment with moderate to high ethylene producing fruits or vegetables such as tomatoes, apples, and peaches. By R. C. Hochmuth

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Preventing powdery mildew in your greenhouse

Powdery mildew is probably one of the most common and widely distributed diseases of plants in greenhouse production. This disease is responsible for significant economic losses in many greenhouse floricultural (e.g., roses, violas, African daisy, zinnias) and vegetable (e.g., tomatoes, cucumbers) crops.

owdery mildews are easily recognised by the white, powdery growth of the fungus on infected portions of the plant host. The powdery appearance results from the superficial growth of the fungus as threadlike strands (hyphae) over the plant surface and the production of chains of spores (conidia). Colonies vary in appearance from fluffy and white to sparse and grey. Powdery mildew fungi usually attack young developing shoots, foliage, stems, and flowers but can also colonise mature tissues. Symptoms often first appear on the upper leaf surface but can also develop on lower leaf surfaces. Early symptoms vary and can appear as irregular chlorotic or purple areas or as necrotic lesions, all of which are followed by the typical white, powdery appearance. Other symptoms include atypical scablike lesions, witches’-brooms, twisting and distortion of newly emerging shoots, premature leaf coloration and drop, slowed or stunted growth, and leaf rolling. In rare but extreme situations, heavy infections cause plant death. Although diagnosis of powdery mildew is not difficult, symptoms often escape early detection if plants are not periodically monitored since symptoms can first develop on lower or middle leaves. This helps explain reports of sudden “explosions” of disease when the percentage of infected leaves increases from 10% to 70% in one week. Development of powdery mildew in the greenhouse is influenced by many environmental factors including temperature, RH, light level, and air circulation. Unfortunately, greenhouses

usually provide optimum levels for all of these conditions. Optimum conditions include moderate temperatures (20-30°C), high humidity (>95% RH), and fairly low light intensities or shade.

disease management Although chemical control continues to be a key component of management of powdery mildew in the greenhouse, other strategies complement and enhance control efforts.

Culture and Pathogen Identification • Maintain adequate plant spacing to reduce RH levels in the plant canopy. This also helps to obtain good coverage with fungicide sprays. • Maintain RH levels below ~ 93% by properly timed venting and heating. • Identify the particular powdery mildew fungus in order to anticipate the potential for spread to other plants in the house. • Syringing or applying water directly to leaves of some greenhouse crops discourages germination of conidia and helps to wash conidia off leaf surfaces. This procedure works for some crops provided other types of foliar diseases favoured by leaf wetness are not common problems for that crop.

Monitoring and Sanitation • Carefully examine and inspect new cuttings, seedlings, and plugs upon arrival. Never use diseased plant material. • Scout for disease on a regular schedule to identify outbreaks before they become widespread. This typically involves examining one out of 30 plants each week. It is helpful to

concentrate on the middle and lower leaves since infections often start in these leaves. Once disease is detected, examine one out of 10 plants every week. Continue with this schedule until plants are free of disease for at least three weeks. Thereafter, resume weekly scouting of one plant out of 30. • All diseased tissues should be removed as soon as they are detected and immediately placed in a plastic bag to avoid carrying infected material through the house. • All production areas should be thoroughly cleaned and plant debris removed between crops and production cycles. This includes removing all weeds in and around the greenhouse. Eradication sprays should be applied as soon as symptoms are first observed since early control is critical!!! Monitor and rotate the types of compounds used to avoid development of fungicide resistance in the powdery mildew population. The diversity of products currently registered and effective for greenhouse use makes fungicide resistance management much easier than in the past. Lastly, but most importantly; consult the label before applying any pesticide. By Sharon Douglas

JACO BOER R.I.P.

Jaco Boer

We have been friends over an extensive period of time with Jaco Boer. He was always a source of information and happily shared technical information when required to round off an editorial. Since the founding of Undercover Farming Jaco became known to us and we shared his enthusiasm when he started Hytech Agriculture. It was a sad moment in time on 30 October when the news of his passing away reached us and, having been associated with him and supported through his presence at Conferences and in the publication, we will miss him in person. Rest in peace, dear friend; your job on Earth has been well done! Our sincerest condolences go to his family and co-workers at Hytech Agriculture. Suzanne Oosthuizen (Director) and Johan Swiegers (Editor).

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Coping with physiological disorders in lettuce Nowadays, lettuce is becoming an increasingly important vegetable in salads, especially in urban areas and found on most home and restaurant table servings in South Africa and globally.

t is a cool season crop, very sensitive to high temperatures, and grows best within a temperature range of 17°-27°C during the day and 3°-12 °C at night. Cool nights are ideal for good quality lettuce. Lettuce grows best in areas having mild summers and mild winters. Night temperatures below 3°C can retard growth rate. Lettuce does not suffer from light frost and winter cold, except near maturity. Severe frost before harvest can scorch leaves and heads. Matured crisp head lettuce can get frost damage if not harvested immediately. During the hot summer months of South Africa, lettuce has poor head development or loose heads, a bitter taste, and physiological disorders such as ribbiness, bolting, multiple-heads and high internal stem growth. At temperatures above 27°C, most of the cultivars do not germinate. Under higher temperatures lettuce quality will deteriorate with the accumulation of bitter latex in the veins and leaves becoming tougher. These conditions also promote premature seed stalk

development, i.e. bolting. Cultivar selection is important when growing lettuce during summer in soilless conditions. A research conducted at ARC-VOPI in a 40% black and white shade net house showed that good yield of high quality crisp head lettuce can be obtained when grown in a GFT system during the summer season. Generally, the internal stem should not be more than half the head height, i.e.

it should not be more than 0.50 core ratio (stem height to head height). If the core ratio is more than 0.50, it indicates that the plant is not growing in a favourable environment. Cultivars that have a short internal stem generally indicate resistance to bolting. Long internal stem height indicates that the plant is about to bolt. Cultivars with a protruding growth of the midrib caused by ribbing are considered unmarketable. This is because the prominent midrib is easily snapped when wrapping crisp head lettuce. This results in an unattractive discolouration of the affected area due to damaged respiration cells of the affected area.

Bolting Bolting is a serious physiological disorder caused by the formation of an elongated stalk with flowers and, subsequently, develops seed. Bolting in lettuce causes the leaves to be bitter and tough. It occurs under conditions where plants are exposed to high temperatures during the early stages of growth. ARC-VOPI

Handling excess flowers at Royal Flora Holland Flowers are often received in amounts of stem that were not advised to the auction in advance. Also, new flower farmers send to the auction without examining the auction’s available quantities at any particular time of the year.

ecause of a certain amount of excess therefore occurs Royal Flora Holland had to restructure somehow. During consultation sessions this spring, national and international members of Royal FloraHolland gave their opinion on how to strengthen the auction clock in future. One of the themes related to the strengthening of the auction clock is the re-auctioning effect. During these sessions, re-auctioning and its consequences were discussed, amongst other things. It was also discussed whether the excess policy was recognizable and known. It emerged that almost 60% of the growers had heard of the excess policy but did not yet know how this policy was implemented by Royal FloraHolland.

Growers who supply daily have a place in the auction groups. When they receive an unpredictable supply, it causes an excess. If a flower grower delivers more than normal amount of stems to the auction without prior notice, it is analysed by a special electronic system taking into account what the auction already received of the particular type of flower. This Supply Information System (SIF) then counts what amount of flowers is available in the particular week as against the previous week and arrives at the Total Offering for auction. The SIF awards points for certain criteria; the higher the points, the higher the excess. The system anticipates the amount of excess and reports it to the auctioneer before the start of the auction. He then evaluates this according to

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individual and market situations. It could be that a grower or nursery expanded or experienced an excellent production season but this is not considered an excess. The auctioneers from different locations harmonise the situation together. When an unpredicted flower grower’s stock is found and no previous data of the grower’s delivery to the auction found, it could be placed in the ‘excessive re-auction group’. After the auction the auctioneer will contact the producer to fill him in on the next auction days. Regular and predictable supply of produce to the auction is important to establish best prices at an auction. The flower grower that anticipates a higher production and new flower producer who wishes to sell on the auction, should contact the auctioneer in advance to safeguard them from excessive delivery without notice and also to ensure fetching the best price at the auction. FH

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Apples and deciduous fruit undercover

in Lesotho

What started as supplying Deciduous Fruit seedlings to a neighbouring country 13 years ago, has now evolved into a long term partnership set to boost Lesotho’s fruit industry. The key role players in this significant collaboration are the Lesotho Government, World Bank, PSC (Private Sector Competitive) and South African based company Stargrow Africa.

his collaboration has been further endorsed by the Prime Minister of Lesotho, Tom Thabane, via the signing of a Memorandum of Understanding on Tuesday, 16 October between these parties. A private sector initiative is spearheaded by Stargrow Africa, whereby the Lesotho Government will be investing the primary capital by means of the Lesotho National Development Corporation (LNDC), and secondary funding supplied by the World Bank. Bordering South Africa, Lesotho is known for its fertile soil, which is ideal for growing an assortment of fruit, mostly deciduous. The Lesotho Department of Agriculture approached Stargrow Africa for assistance, with a number of challenges being experienced. With the support from the World Bank and PSC, a pilot project was initiated four years ago, which saw Stargrow Africa not only manage and overcome the challenges, but also increased the country’s fruit supply from 2ha to 27ha in 2017 (mainly apples, but also pears and peaches). One of the problem areas identified

Lesotho is known for its fertile soil, which is ideal for growing an assortment of fruit, mostly deciduous.

The apple seedling orchard under shade net with dripper irrigation installed.

was the late frost, which is common to Lesotho, and unless dealt with in the proper manner, it can be devastating to the agricultural sector. Stargrow Africa’s team overcame this by simply identifying a north facing slope, where the trees could be planted in a south-north direction facing the sun. The orchards are also covered in hail-nets, which not only protects the trees from hail, but

also wind and pests such as birds and insects. In this Memorandum of Understanding a section of communal land 100km north of Lesotho’s capital, Maseru (and approximately 40km from Ficksburg in the Free State), has been identified as prime land for getting this project off the ground. This section of 18 land will allow for community

Co-creating water re-use and efficiency for industries in SA During November 2018 a fact finding and advice mission was organised by the Embassy of the Kingdom of the Netherlands and Aqualinks in South Africa. Ridder (www.ridder.com) was part of a match-making mission between Dutch water technology providers and industries in South Africa.

his mission was aimed at Co-creating Water Re-Use and Efficiency for Industries in South Africa. While horticulture is normally not an industry, it makes use of the same high technical solutions. The match-making started in June 2019, when several South African companies participated in a workshop to articulate the demands and opportunities for improved wastewater treatment and water efficiency in their respective companies. Following the workshop, Dutch water technology service providers were engaged that would be able to co-create. The visit of the Dutch companies took place during 19-21 November, with a networking

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reception on the 19th where the South African companies could also meet, and sites were visited from 19-21 November. The match-making was an initiative of the Partners for Water Programme, implemented by the Netherlands Enterprise Agency and the Netherlands Water Partnership (www.netherlandswaterpartnership. nl), and supported by the Netherlands Embassy in South Africa (www.netherlandsandyou.nl). To facilitate the match-making, AquaLinks Research and Implementation (www.aqualinks.co.za) was involved on the South African side and Yuniko (www.yuniko.nl) on the Dutch side.

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Integrated pest management in the greenhouse So much has been published about Integrated Pest Management (IPM) and yet farmers are losing crops because of ignoring this important of their business or not training their greenhouse staff in IPM. Choices for greenhouse pest management can vary depending on the size of a greenhouse and how a greenhouse is used. Basic integrated pest

asic integrated pest management practices such as inspecting incoming plants, weekly monitoring, sound cultural practices, pest identification and problem diagnosis are similar, whether a greenhouse is 1,000 mÂ˛ or 10,000 mÂ˛ in size.

Integrated Pest Management Integrated pest management involves inspecting incoming plants, consistent monitoring, using good cultural practices, accurately diagnosing plant problems and pest management decisions.

Incoming Plant material Inspecting incoming plant material is very important to prevent problems in greenhouses. Foliage of incoming plants should be carefully inspected for insect pests such as aphids, whiteflies and thrips, diseases such as powdery mildews, downy mildews, Botrytis blight and symptoms of virus infection or foliar nematodes. Stems and crowns of plants should be inspected for insects any abnormalities caused by disease and root health should be inspected.

Quarantine If you find insect activity and decide to keep the shipment, quarantine the plants from others in the greenhouse and treat immediately. Plants with root rot diseases will unlikely recover in a reasonable length of time for retail sale even after treatment and those with viral or bacterial diseases or foliar nematodes should not be accepted.

Monitoring Greenhouses should have a weekly, integrated pest management (IPM) program in place to detect problems early. A regular monitoring program using lesotho

involvement, which will ultimately lead to job creation. The size of this piece of land is approximately 1 000ha. The projected start date for Phase 1 of this venture is 2019, which will see 20ha of land under fruit trees (approximately 33 000 fruit trees, consisting mainly of apple

Inspecting (scouting) plants in the greenhouse on a regular basis ensure early detection of insects or pests.

sticky cards and plant inspection is the basis of all pest management programs.

Using Sticky Cards Yellow sticky cards are recommended to detect winged insects including adult stages of fungus gnats, thrips and whiteflies. Use small, 10x15cm cards and change them each week to keep track of hot spots and to prevent them from becoming unsightly. Place some cards just above the plant canopy (to detect thrips and whiteflies) and some cards at pot rim level to detect fungus gnats.

the underside of leaves for insect pests and inspect root systems to determine plant health.

Record-keeping

Plant Inspection

Record information collected from sticky card counts and plant inspection including the pest numbers and their location, root health, overall plant health and the numbers and species of plants inspected. Records of pest numbers and locations will help to identify sources of pests and indicate whether treatment is needed or if control measures were successful or need repeating.

Plant inspection can be done when handwatering or cleaning plants in addition to a regular weekly inspection. To conduct a weekly inspection, randomly select plants at ten locations in an area of 300 mÂ˛ examining plants on each side of the aisle. Start this pattern at a slightly different location each week, walking through the greenhouse in a zigzag pattern down the walkway. Use a 10x hand lens to examine

Diagnosis Accurate diagnosis is key to management whether you choose pesticides or biological control. Many pesticides and most natural enemies are often specific to just one pest or group of pests. If you are having trouble diagnosing a problem, contact the ARC-VOPI entomologist or a University Horticultural Department for assistance.

orchards). The goal is to have the entire 1 000ha of land under fruit trees in the next 10 years. Although orchards are the primary focus, the company will also look to establish nurseries, as well as packing facilities and cold rooms. The size of the land identified equates to 1,65 million fruit trees, mostly apple orchards. The total production is expected to be 8,4 million crates, which

will fill 1 650 containers. Most of the fruit will be supplied to the local markets in Lesotho, with secondary supply to the South African markets in Bloemfontein and Gauteng. The ultimate goal would be to export to the Middle and Far East, the Americas and rest of Africa, via the Durban harbour. During this time Stargrow Africa will appoint a team to oversee the project from start to finish.

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Time to invest in aquaponics

Aquaponics offers many advantages that make it a suitable investment option. Firstly, it offers a mechanism for making profit and if linked to a Satellite Grower Scheme, can create wealth for the stakeholders involved in this business. A PPP co-funding model can be used to satisfy the need that the investor has for returns and the ability of the State to contribute resources to increase the scale of the business and benefit the employees as equity partners.

quaponics crops are renowned for their excellent flavour due to the abundance of natural nutrients and water which enable the plants to grow optimally. This, combined with the healthiness of the crops, is the greatest selling point for aquaponics farmers. As we do not use traditional pesticides in an aquaponics system, the crops not only taste good but are also very healthy to eat. Create a business and you create jobs. As a business aquaponics generates about 1.5 permanent employment opportunities per 300m2 tunnel erected. The day-to-day work load is not high but picking and packing of crops is time consuming and requires a careful hand, necessitating the use of labour. Farming generally occurs in rural areas and as such an investment into an aquaponics facility keeps people in the rural areas by providing employment there. This offers the State a massive advantage as it reduces urban migration. Aquaponics is an intensive activity requiring minimal space and, as it does not rely on the soil, can be done in marginal areas. As such, farmland that is unsuitable for traditional crop or

A mix of lettuce growing in an aquaponics system. These crops take 6 weeks in summer and 8 weeks in winter from seed to market.

stock farming can usually be utilised for aquaponics. Aquaponics is dependent on a stable supply of electricity but does not require much electricity. Our 300m2 aquaponics tunnels utilise around 1kW of power each and as such, the entire operation can be backed up with an ATS generator at an affordable rate. A 300m2 tunnel aquaponics system utilises less than 500ℓ of water per day to produce both fish and vegetables, as such aquaponics is very economical in terms of water use. The quality of the

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