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MAY - JUNE 2019 Volume 16 No 3


Semperflora - Flower producers excell Page 4

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crop production



Smart water management Page 12

Energy saving for ornamentals Page 14

Sweet pepper success Page 8

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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

Scripture for Guidance

Psalm 25:3 “Show me your ways, O Lord, teach me your paths, guide me in your Truth and teach me, for you are God my Saviour and my hope is in you all day long.”

Contents 4 Semperflora thinking ahead whilst holding their own 6 Greenhouse Domestic Principles Save Eventual Losses 8 Sweet Pepper Success 10 Managing Botrytis on Floriculture Crops 12 Smart water management an imperative for

FRONT PAGE: Foto: Cees Vooys and Willem Slootweg of Semperflora in one of their greenhouses. See pages 4 & 5.


commercial cannabis and hemp cultivation in SA


Prevent the accumulation of sodium (Na) and chloride (Cl)

14 Energy-Saving Climate Control for Cultivating


Greenhouse Ornamentals

16 Starting up a Cannabis Growing Greenhouse System 17 Greenhouse Technologies – Passion for Greenhouse Plant Production

18 How Do Flowers Absorb Dye? 19 Agbiz’s reaction on the SONA 19 Subscription form


14 16


ith so much negative news in the world, one finds it hard to approach anybody to talk to and hear good news and a positive attitude towards the future. Although we have internal situations affecting the general population, other countries in the world are facing dilemmas too. It is therefore only a pleasure to visit a flower farm where the owners are positive about their business, do something about their market to remain in business and as a matter of fact, have their young adults gearing up to come into the business to ensure it will go on long after they retire. The country’s flower farmers reduced in number largely because of the zooming in on Kenya and other mid-African countries where European companies made heavy inroads and the governments of these African countries were only too willing to accommodate them. If only we in agriculture and floriculture could have received similar benefits from government at the time, possibly we could have saved all the employees their jobs and kept the contribution from floral exports to the GDP for South Africa. No use crying over spilt milk; let us look to the future! It depends largely on each producer of fresh produce, flowers and other agricultural produce to diverse on their farm, find a product for which there is a sustainable market and get on with it. The wider the range of products you can farm with, the better your chances are of earning a steady income and provide employment. During winter – and it seems to be a pretty harsh one this season – the greenhouse grower relies heavily on energy to heat his production area. With our increasing electricity costs, it is of importance to manage climate in the greenhouses as best possible to curb expenses while simultaneously obtaining as much as possible produce from our plants. We invite our readers to send a picture with caption and even a message of interesting facts they come across on their farms to us. In this way, our readers around the country is bound together as an undercover farming family! Keep warm this winter.

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Semperflora thinking ahead whilst holding their own

Semperflora (Flowers forever) - this remarkable flower production unit with Willem Slootweg and Cees Vooys at the helm started way back in 1986 on a small portion of the land they now extensively cover. Semperflora at the moment grows 23 varieties of flowers, currently produced on 6,2 hectares spread over 25 greenhouses in the Mooinooi vicinity.


he company prides itself for being absolutely GlobalGap certified and is inspected or audited at least once a year. Both owners have a minimalistic approach to the way they run the business, being acutely aware of pitfalls along the way. They do not have a heating or cooling system and the flowers they grow can deal with such climates. Some products like ornamental Kale, Delphiniums and Lisianthus do well without climate control. Some of the greenhouses are also fitted with screens to reduce heat stress in summertime. Heating and cooling are managed by electrically driven equipment which lift the ends of the plastic covered greenhouses or letting them down to retain heat. According to Willem plans to automate this process for increased management success are on the table. The new greenhouses are build a meter higher for better airflow and increased micro-climate. During summer months, that is from November to April they do well with exports to the North as the Northern hemisphere then have their winter. Semperflora send the majority of their products to Multiflora but they do have a direct client list as well which they are currently extending in order to fetch a

good price but also to obtain extended product supply. They are doing trials with ornamental grasses for which they already have a good market in Europe – South Africa has not really caught fire over this product, but Willem and Cees relentlessly carries on planting new varieties which they find a good market for in the North. According to them they plant these for the past fifteen years and there is a slow but growing interest for ornamental grasses as filling in bouquets locally. Ornamental grass must be handled quickly to maintain its

A few of the flower packers at work at Semperflora.

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Cees Vooys and Willem Slootweg proudly shows some of their popular types of flowers.

appearance and therefore, especially with exports the company makes sure it is delivered in the shortest time possible. Although Semperflora grows 23 types of cut flower products, seven of these

A view inside one of the 25 greenhouses at Semperflora.

make out 70% of their main income. It still is important to grow the rest as there is a steady market for the lesser popular types but even these types are now growing in popularity. They also fall in different climate zones therefore keeps the workers busy and provide a steady income. The seven higher income types are ornamental grasses, gypsophola, Lisianthus, Celosia, Limonium, Statice and Lysimachia. Several other flower types that are popular locally and in Europe are grown throughout, but when demand drop totally it is discarded and a new product developed and 5

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marketed in its place. This is all about a company’s good marketing strategy. Since Semperflora is GlobalGap certified, integrated pest management is used ninety percent of the time. Only here and there when certain small outbreaks of insect pests are found, non-biological matter would be dosed to curb losses, but these are - generally speaking - minor in case. In the flowering greenhouses coloured sticky tabs are hung above flowers to detect which type of insect prevails. Retail companies in Europe are all very strict in their approach to imported items – be it edible or non-edible produce and hence GlobalGap certification applies to flowers and plants as well. Locally, GlobalGap representatives are in all the main agricultural production areas in South Africa. A situation that seems unsurmountable for flower producers in South Africa, is the registration of pest or insect

In between the greenhouses at Semperflora ornamental grasses are grown. These are very popular in European bouquets. Insert: The latest acquirement of grass type currently on trial.

control products for use in this country by local producers. Over years, new diseases and even insects came to the fore, but as it is known, research and development on these products take at least ten years and then possibly another ten for registration. Unfortunately, the local flower product

producers diminished dramatically in number over past years and therefor scale of economies comes into play for manufacturers of such treatments. South African farmers are not allowed to use European or other countries’ pesticides or insecticides, thus growers like Semperflora must devise methods biologically to keep their plants healthy and still produce a top-quality product.

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Greenhouse Domestic Principles Save Eventual Losses

If you have had re-occurring problems with diseases such as Pythium root rot or insects such as fungus gnats, perhaps your greenhouse and potting areas need a good cleaning. Over the course of growing a crop, infectious microbes accumulate and algae flourish on moist surfaces harbouring fungus gnats.


ttention to greenhouse Irrigation systems sanitation and disinfecting should also be cleaned are steps that growers can to remove dirt and do between crop cycles. organism build-up Some growers wait until the week (also called biofilm) at before planting a greenhouse before the end of the growing cleaning debris from the previous season. Growers often growing season. It is better to clean use products labelled as early as possible to eliminate overfor cleaning irrigation wintering sites for pests to reduce systems such as sulfuric their populations prior to the spring acid plus a wetting agent growing season. Pests are much easier or sanitizers containing to prevent than to cure. hydrogen peroxide and peroxyacetic acid Although disinfecting should be done to flush out slime and routinely, timing does not always permit debris. this extra effort. Take the opportunity to thoroughly clean greenhouses Benefits to between crop cycles when greenhouses Disinfecting the are totally empty. Greenhouse Cleaning Many pathogens can be managed to Cleaning involves physically removing some degree, using weeds, debris and soil and is the first disinfectants. For step prior to disinfecting a greenhouse example, dust particles and equipment. Some growers use a from fallen growing “Shop Vacuum cleaner� on concrete medium or pots can and covered floors to remove debris. contain bacteria or fungi Greenhouse assistants should wear clean overalls and by Soil and organic residues from plants hygiene conscious. such as Rhizoctonia or and growing media reduce the Pythium. Disinfectants effectiveness of disinfectants. There are are brought into the greenhouse will help control these pathogens. In some cleaners specifically developed for through water supplies and from peat addition to plant pathogens, some greenhouse use to remove algae, dirt in the growing media. Once in a warm, disinfectants are also labelled for and hard water deposits. High pressure moist environment with fertilizer, the managing algae which is a breeding power washing with soap and water is algae flourish. ground for fungus also an option. Soap Proper water management and gnats and shore flies. Cleaning involves is especially useful fertilizing can help to slow algae growth. in removing greasy Managing Algae physically removing Avoid over-watering slow-growing deposits however, Algae are a diverse weeds, debris and soil and plants and especially crops early in the thorough rinsing grouping of plants is the first step prior to production cycle. Allow the surface of is needed because that occur in a the media to dry out between watering. disinfecting a greenhouse soap residues can wide range of Avoid excessive fertilizer runoff and and equipment. inactivate certain environments. Algae puddling water on floors, benches, and disinfectants. growth on walks, greenhouse surfaces. The greenhouse Begin at the top and work your way water pipes, equipment, greenhouse floor should be level and drain properly down. Sweep down walls and internal coverings, on or under benches and in to prevent the pooling of water. structures and clean the floor of soil, pots is an ongoing problem for growers. Algae management involves an organic matter and weeds. Disease Algae form an impermeable layer on the integrated approach involving sanitation, causing organisms can be lodged media surface that prevents wetting of environmental modification and frequent on rafters, window ledges, tops of the media and can clog irrigation and use of disinfectants. overhead piping and folds in plastic. misting lines, and emitters. Greenhouse Benches and Extra care is needed to clean these It is a food source for insect pests and Worktables areas and textured surfaces such as causes slippery walkways that can be a concrete and wood which can hide If possible, use benches made of wire liability risk for workers and customers. many kinds of organisms. that can be easily disinfected. Wood Recent studies have shown that algae

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Greenhouse Domestic Principles


benches can be a source for root rot diseases and insect infestations. Algae tend to grow on the surface of the wood creating an ideal environment for fungus gnats and shore flies, and plant pathogens can grow within the wood. Plants rooting through containers into the wood will develop root rot if conditions are favourable for pathogen activity. Disinfect benches between crop cycles but keep in mind that disinfectants are not protectants. They may eradicate certain pathogens but will have little residual activity. Bench tops and worktables should be made of a non-porous surface such as a laminate that can be easily disinfected. Avoid using bare wood for these tasks. Cleaning Containers Plant pathogens such as Pythium, Rhizoctonia and Thielaviopsis can survive in root debris or soil particles on greenhouse surfaces. If a crop had a disease problem, then avoid re-using containers. It is also a good idea to avoid planting crops that are prone to Thielaviopsis problems, such as pansies, in containers that have been previously used. Research has shown that Thielaviopsis spores are capable of surviving on recycled plug trays and infecting new crops. Containers to be reused should be washed thoroughly to remove soil particles and plant debris before being treated with a disinfectant, even if there is no evidence of disease in the crop. Debris and organic matter can protect pathogens from encountering the disinfectant solution. Disinfectant products have different properties. If possible, disinfectants

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Foot baths should be located at all entrances to greenhouses. Disinfecting the sole of shoes or boots of all entrants are an absolute must for proper hygiene management in greenhouses.

Set up washing stations for hand washing should be used on a routine basis both and foot baths at the entrances of each as part of a pre-crop clean-up program greenhouse, especially propagation and during the cropping cycle. houses. Steps to Prevent Disease Lastly, all staff engaged in production Contamination or harvesting should wear clean overalls Disinfect benches, preferably made and boots and be of good health. They of wire. Pots, flats must be regularly and trays should be Greenhouse staff are also made aware of new or disinfected. the eyes and the ears for personal and work Wood benches can anything that might seem area hygiene in be a source for root order to ensure all wrong and should be rot diseases and greenhouses are free insect infestations. advised to report this to of any infection or Algae growing on management immediately. pests. Greenhouse wood surfaces create staff are also the eyes an ideal environment and the ears for anything that might seem for fungus gnats. Plant pathogens such wrong and should be advised to report as Pythium can grow within the wood this to management immediately. and plants rooting into the wood can By: R. Ferguson become infected.

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Sweet Pepper Success

Sweet pepper is an important and popular crop, consumed worldwide and enjoyed in various forms. Amongst all those various forms, the blocky shaped sweet pepper remains the favourite. Snacking and larger conical types have become quite popular and satisfy the need for convenience and unique taste. And although the driving force for this change stems from consumer behaviour and demand, it is made possible by breeding companies like Enza Zaden.


lthough the name may be new to some, Enza Zaden celebrated its 80-year anniversary in 2018. The international vegetable breeding company, originally from Enkhuizen in the Netherlands, launched its local subsidiary in Gauteng, Centurion in August 2017. Sweet pepper is one of their main crops which also includes their unique Tribelli® brand of conical peppers.

Variation “The consumer is looking for different ways of using sweet pepper. This is what Tribelli Mini and Tribelli XL offer: healthy, tasty and convenient snacking and cooking. Hot peppers with varying pungencies are also gaining popularity, especially in Europe, but conventional blocky peppers remain the top commodity of sweet pepper,” says Antonio Sances-Lopez, Crop Breeding Manager for sweet pepper at Enza Zaden. Integrated Pest Management One of the biggest changes worldwide according to Antonio, who is based at Enza Zaden Spain, is the move to Integrated Pest Management (IPM) and ultimately to organic production. One example is Murcia in Spain where 25% of the production is already organic. The remaining part is on IPM where conventional fertilisers are still permitted. This is also seen in other markets worldwide: fresh produce that is free from any chemical residues is becoming a prerequisite for consumers in developed markets. “This means that there is an increased need by growers for superior resistance

in plants. Our breeding efforts are soil salinity becomes more of an issue aimed on adding value. One way of in many countries in the Mediterranean achieving this is by developing varieties and Mexican production regions. that require lower input costs: varieties Breeding efforts therefor aim to develop with superior resistance need less varieties with strong root systems that chemical spraying.” either cope with high brackish soils or require lower EC levels without Resistant varieties compromising yield and quality,” “We see an increase in disease pressure says Antonio. “We have a very wide nationally,” says Johan Stassen, Area assortment backed by a global breeding Manager and Product Specialist at Enza program that offers varieties available Zaden South Africa. “With the support to approach these market changes and of our laboratories in Enkhuizen in the challenges with.” Netherlands, we were able to identify Partnership and the breaking long-term relations stain of Tomato Spotted Wilt Virus With local screening One of the biggest changes (TSWV) in 2016 Enza Zaden tests the worldwide according to in the Limpopo latest genetics and Antonio, who is based Province.” Eastern identifies varieties Cape growers that work for the at Enza Zaden Spain, is traditionally grew local climate and the move to Integrated sweet peppers grower needs. Pest Management (IPM) which lacked “One of the biggest and ultimately to organic resistance, but now benefits of having production. they can no longer a local entity in do without this South Africa is resistance. “TSWV that we are able & Tm resistances are standard on all to respond quickly to ever changing new Enza Zaden varieties.” markets. And we are backed by a global Similarly, Leveillula taurica (Lt) is a network of expertise. We have direct problem plaguing the growers, not only communication to breeders and product in the Eastern Cape, but all over the specialist internationally,” says Matome country. Ramokgopa, General Manager of Enza “Although management and spraying Zaden South Africa. can delay the onset, resistance is key. “As an independent family owned Our new generation sweet peppers like company, now for the third generation, Titanio, Diamo and Calcio (E20B.10242) we understand the importance of have shown superior resistance too. relationship. It is part of our company Such resistance has a big cost-saving culture to form partnership and nurture benefit for growers,” adds Johan. long-term relations with our customers Strong root systems and find solutions through plant genetics.” “Water quality and availability, as well as

For more details www.enzazaden.co.za

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Managing Botrytis on Floriculture Crops Botrytis blight (Botrytis cinerea) or grey mould is one of the most common pathogenic fungi found on floriculture crops especially those of great economic importance. Under the right environmental conditions, botrytis blight is fast growing and can infect healthy or senescing plants or plant parts causing rot. Botrytis blight is found widely throughout greenhouses on stock plants, in propagation and production areas, and is a concern for many growers.


n general, botrytis blight has a very broad host range. Infection on high value potted crops such as potted rose, gerbera daisies, and cyclamens is of concern. Biology of Botrytis Blight Greenhouse temperatures between 15 to 23°C and a relative humidity greater than 90% from irrigation is the optimal environment for botrytis blight to occur. In association with rapid changes in humidity, conidia (spores) are often dispersed in the greenhouse environment by air circulation, splash from irrigation water, and/or from improper sanitation practices. Once dispersed in the greenhouse, infection can occur directly on plant stems, leaves, bracts, flower petals, and on fruits; through natural openings, or through wounds caused by cutting harvest, mechanical damage by automation, and/or by handling. Conidia germination typically occurs in less than three hours in a film of water on plant surfaces caused by increased humidity or by irrigation events. Conidia will infect plant tissue by means of conidial germ tubes or by hyphal (long, branching structure of a fungus) growth from previously colonized dead plant parts or plant debris that contacts healthy plant tissue. Infection can be stimulated by nutrient depletion of leaves. Also, shattering of flowers, fallen petals, and pollen deposition from overhead hanging baskets can provide an energy source

Gerbera leaf damped off at the substrate surface with botrytis blight.

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for the fungus and facilitate infection of adjacent healthy crops. Infected cells will collapse and start to disintegrate as the fungus grows. As fungal growth occurs, plant tissue will begin to soften and rot. During this time, conidiophores (specialized stalk-like structure) will form and bear the conidia, thus sporulation and infection can reoccur within less than eight hours of initial infection. For long-term survival in the green­ house, sclerotium (harden mass of branching hyphae or mycelium) form in colonized plant tissues or in soilless mixes. Under appropriate greenhouse conditions, sclerotia will germinate and produce conidial inoculum. Once this occurs, previously infected crops can be re-infected or new crops can become infected and the disease cycle starts again.

Cyclamen flower infected with Botrytis Blight.

greenhouse growers because the plant pathogen could rapidly invade host tissues and quickly produce abundant conidia that are easily distributed by air currents. An integrated strategy combing cultural, environmental, and chemical or biological Diagnosing Symptoms practices and management techniques will and Signs effectively reduce or eliminate the everSymptoms of botrytis blight on so-present threat in the greenhouse. propagation material include leaf loss and Cultural Control cutting rot. Symptoms of botrytis blight Cultural control of botrytis blight in the can range from discoloured spots or greenhouse first starts with prevention. “ghost spots” or blights on plant leaves, All plant material including plugs, liners, bracts, or flower petals. Premature stock plants, and plant flower bud or flower material for finishing Once dispersed in the loss can also occur. should be thoroughly greenhouse, infection can Stem cankers and inspected for plant crown, bulb, or occur directly on plant diseases and insects corm rot may occur stems, leaves, bracts, flower prior to placement in resulting in wilting petals, and on fruits; through the greenhouse. and collapse of the natural openings, or through An on-site quarantine plant or dampingarea should be wounds caused by cutting off at the substrate established, separate surface. harvest, mechanical damage from the production Growers should by automation, and/or by facility for any plant familiarize handling. material not produced themselves with the by the greenhouse signs of botrytis blight. Most commonly, to eliminate the potential introduction greenhouse growers will encounter of pathogens or pests in the production the mass of fuzz-like, white to greyishfacility. If plants are damaged, diseased, or brown fungal colonies on plant material. dying upon arrival, plant material should However, with a hand lens or with an be rejected. This will eliminate future on-site microscope, growers can detect disease problems that may arise during mycelia growth or the hard, blackened, crop culture. irregular shaped sclerotium structure. Greenhouse floors or benches should Botrytis Blight Management be properly sanitized between crops. Control of botrytis blight is challenging for Production areas should be free of 11

Managing Botrytis


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of production areas will elevate the any plant debris from previous crops and opportunities for infection to occur weeds. Tools used for propagation should during the night. be thoroughly sanitized. Chemical Control Monitoring and managing crops by Chemical control of botrytis blight has providing adequate plant spacing, limit become complicated for growers because leaf wetness to three to four hours, and of repeated applications of fungicides remove excessive foliage or flowers with the same mode of action that can whenever possible, will reduce the result in resistant populations of Botrytis. potential for infection. If a plant in Resistance and insensitive strains of B. production is infected, it is recommended cinerea have occurred when growers to remove the plant by placing it in continuously applied benzimidazole a sealed plastic bag to prevent spore and dicarboximide dispersal and discard fungicides. However, immediately. Do not If a plant in production is benzimidazole place infected plants infected, it is recommended or dicarboximide with other organic to remove the plant by fungicides are only wastes as Botrytis placing it in a sealed plastic useful in controlling could survive as a bag to prevent spore dispersal non-resistant strains saprophyte. of B. cinerea. and discard immediately. Environmental Other registered Control fungicides effective in controlling Manipulating and controlling the botrytis blight in the greenhouse include, greenhouse environment by reducing chlorothalonil, copper hydroxide, copper the relative humidity below 85% will sulphate pentahydrate, and mancozeb. prevent the optimal growing conditions Additionally, tank mixtures that include for Botrytis. Increased air circulation a single-site and a multisite fungicide at by a horizontal airflow system will reduced dosages can assist in controlling prevent stagnate air from occurring and botrytis blight and decrease the possibility promotes drying of wet plant surfaces. of resistance. Also, providing ventilation and heat at sunset to drive moisture-laden air out It is recommended to follow all fungicide

labels as directed from the manufacture. Trialling fungicides or tank mixtures on an individual plant of each species to determine phytotoxicity and the duration of fungicide residue on plant material are recommended. Biological Control In recent years, the use of biological control agents or bio-anatagonistic fungi to control Botrytis has shown to be promising. However, it is recommended to utilize biological fungicides only preventatively for botrytis blight management and do not rely upon them solely for control of Botrytis. Therefor conducting small trials to determine efficacy and effectiveness is recommended. For plant and cut flower exporters, GlobalGap regulations prevent them from using any chemical substances in the greenhouse and therefor investing in biological pest management products and methods is an absolute must. It is recommended that the producer work in close relation with his supplier to apply the correct and economical volumes and to work out a preventative schedule to obtain maximum production and quality flower production. Author: Garrett Owen

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Smart water management an imperative

for commercial cannabis and hemp cultivation in SA

With all signs pointing towards the forthcoming legalisation of both hemp and cannabis for commercial cultivation in South Africa, irrigation expert Charles Cherry believes companies like theirs stand to be major industry role players, thanks to their expertise on water management and the quality control of cannabis crops.


he first licences for growing medical marijuana in South Africa have already been issued and are now awaiting key changes to local legislation in order to legalise cultivation, forward-thinking entrepreneurs in the agri- economics sphere are preparing for what lies ahead. “Smart and effective water and fertilisation management is going to be imperative to assist the cannabis industry across Africa to develop and thrive,” says Cherry, director of Cherry Irrigation, headquartered in Grabouw and with operational bases in Namibia and Angola. “We’ve worked in the

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agri-irrigation sector for over 30 years its general size, scheduling and correct fertigation will be essential to ensure and water remains a precious resource premium growth and optimal crop throughout South Africa and the continent at large. quality and We have already yield sizes,” he We have already researched researched effective explains. “Irrigation effective water management water management scheduling is all and fertigation of cannabis and fertigation of about giving crops cannabis crops water at the right crops and have armed and have armed (optimal) time and ourselves with the skills, ourselves with the just in the right knowledge and expertise to skills, knowledge amounts – taking help growers produce the and expertise factors such as best yields possible.” to help growers plants’ growth produce the best stage, climate conditions and yields possible.” drainage into account.” “While cannabis’s water use is standard for what you would expect of a plant of 13

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Fertigation refers to feeding plants small oil we’re talking about, quality is going amounts of the right kind of fertilisers to matter, as is sustainability, no matter through the irrigation water according the strain of the plant. Our team is to their growth stage. Hemp and currently doing key research to ensure marijuana also grow quite differently, that we are the go-to consultants once with varying water and fertilisation commercial cultivation is given the requirements. green light – pun intended,” Cherry quips. “Cannabis planted in climate-controlled be grown in most parts of the country, Since decriminalising the home use while open-field plantings will most of cannabis in 2018, government has probably be confined to the Western hinted that it is one step closer towards and Eastern Cape granting this and KwaZuluproverbial green Both crops (Cannabis sativa Natal, according light for what has (hemp and marijuana) have to research been dubbed the multiple applications in done to date by “green rush” – the numerous sectors, including the Agricultural collective global Research Council,” thriving hemp and building, clothing and he adds. cannabis markets medical industries that could Cherry believes that help create much-needed jobs – by legalising the local commercial in what is set to be across South Africa. cultivation of a highly competitive cannabis sativa and regulated (hemp and marijuana respectively.) industry, the skills that educated water management consultants and irrigation Both crops have multiple applications companies can offer growers will be a in numerous sectors, including building, key differentiating factor. clothing and medical industries that could help create much-needed jobs “Whether it’s hemp or high-grade CBD

across South Africa. With SA’s neighbour Lesotho already a leader on the continent in terms of granting licences for the cultivation of medical marijuana, we’re scrambling to play catch up, and industry leaders are putting pressure on government to act sooner rather than later – and Cherry believes it will. “We’re exhibiting at the Cannabis Expos in key centres throughout South Africa this year, with the Cape Town expo in April already having generated keen interest,” he says. “We have a stand at the forthcoming Durban leg of the expo from 6 to 9 June and invite interested parties to come and chat to our team. We’ll be happy to advise them on water management and irrigation options for the commercial cultivation of cannabis. “It’s an exciting time for us. We’re active across Southern Africa, we’re in talks with key players and we’re thrilled about the potential of a burgeoning industry. We’re ready to get growing – in South Africa specifically it’s up to government to take the next step,” Cherry concludes.

Contact: Cell 082 492 2508 or tel 021 859 4246. E-mail charlescherryirrigation.com GRABOUW (Western Cape, South Africa)

Prevent the accumulation of sodium (Na) and chloride (Cl) Feeding water with low Na and Cl levels must be used when nutrient solutions are recycled (closed system) in order to prevent the accumulation of these ions. The Dutch overcame this problem by building plastic lined reservoirs, filling it with rainwater from their glasshouse roofs.


y mixing Na- and Cl-rich water with rainwater, the Na and Cl concentrations were lowered to safe levels. Since low EC crops such as roses can only absorb 5 ppm Na and 11 ppm Cl, these are the highest levels that may be allowed in the feeding water for roses in a 100% closed system. A saline tolerant crop such as tomatoes can remove 16 ppm Na and 32 ppm Cl, allowing tomatoes to be recycled with feeding water containing these, or lower, Na and Cl levels. Should water with higher Na and Cl levels be used for a limited recycling period (until the red lights start flashing) saline sensitive crops should be flushed as soon as root zone levels reach 69 ppm Na or 107 ppm Cl. Most greenhouse crops will be unaffected with Na levels below 115 and Cl below 178 ppm. Saline tolerant crops such as tomatoes will be able to withstand levels of up to 184 and

284 ppm Na and Cl respectively. Should these levels be exceeded, yield and quality losses will occur. Adjusting nutrient levels As a crop develops from the vegetative to reproductive stage, or with a change in climatic conditions, its nutritional needs A gutter system can be seen running through the top of this change. The use of leaf picture between greenhouses. The rainwater is collected and deficiency or toxicity runs into a reservoir. The water is tested and filtered if necessary symptoms to identify before irrigation takes place. nutritional problems the last few years, can help growers to is ineffective. It is identify nutritional imbalances before impossible to avoid yield and quality it is reflected in the leaves and before losses with this approach, even by using damage can be done to the yield quick petiole sap measurements as aid. potential. This procedure is used by the The use of nutrient foliar sprays should Dutch and the Belgians, serving areas not be necessary. Root zone analyses, with high densities of growers. developed in the Netherlands during 19

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Energy-Saving Climate Control

for Cultivating Greenhouse Ornamentals On both sides of the Atlantic, greenhouse growers are faced with the challenge of how to reduce energy costs in greenhouse cultivation. Coordinating lighting and climate control may save greenhouse growers energy.


xperience by growers and research facilities all over the world has shown that precisely coordinating climate control and lighting holds a great potential for savings. It is interesting to take a brief look at the German market, where a climate model developed at the Weihenstephan-Triesdorf University of Applied Sciences (HSWT) has been gaining ground in recent years. Developing an Energy-Saving Model Germany has more than 8,000 producers of ornamental plants with a total of more than 2,000 hectares of greenhouses. These companies generate Figure 1. Schematic representation of the control settings. For the cool morning, heat a significant share of their revenues is normally lowered one to two hours before sunrise. Some growers also lower the temperature two to five hours before sunrise for a long cool morning. (Figures courtesy of at the start of the garden and balcony Hans Haas, Weihenstephan University) planting season in the first weeks of spring and during the Christmas season At dusk, the energy screens are closed. by lowering the temperature in the with winter plants. The heat loss can be further reduced by greenhouse in the morning. Studies have using shade screens. Winter and early spring are thus shown that this cultivation model can important cultivation lead to a reduction Additionally, under-table heating is periods in Germany. recommended due to the reduced air Dynamic temperature control of 25 to 40 percent Many of the plants in energy costs with volume (under the energy or shade in greenhouses is a new and cultivated at this no major investment screens), less energy is lost. Because of unfamiliar concept for the time, e.g. Euphorbia and no loss of plant the higher temperatures, the effect of horticulture sector. It required quality. pulcherrima, need supplemental lighting is highest during a completely new approach to warmth and light, this time (assimilation). In addition, A New Approach so greenhouses climate control parameters. the heat from the lamp is added to Dynamic require heating and the heat reserve. As the heat from temperature some lighting during a sodium-vapor lamp increases leaf control in greenhouses is a new and these periods. The resulting energy temperature by two to three degrees, unfamiliar concept for the horticulture consumption constitutes a considerable the temperature control may need to sector. It required a completely new share of production costs. Therefore, be adjusted. approach to climate control parameters. an energy-saving model for cultivating In the morning, the heating Numerous studies have shown that with ornamental plants was developed temperature, but not the ventilation this model, the quality of the plants is at Weihenstephan University (the temperature, is lowered (cool morning). comparable with that of those cultivated Weihenstephan model), which has been This involves reducing the heating conventionally, (at least) under the adopted by many producers in Germany. temperatures to a light conditions in In contrast to conventional cultivation plant-specific lower Especially on sunny days, southern Germany. with constant day and night limit at least one to natural sunlight warms In practice, the temperatures, the energy-saving model two hours before the air in the greenhouse. Weihenstephan is based on dynamic temperature sunrise. In this model is The heating is switched on control. This involves using natural cultivation phase, implemented sunlight in the early afternoon to build only if the greenhouse is the greenhouse can by setting the up a heat reserve and closing the insufficiently heated after cool down naturally. ventilation ventilation system early to retain this four to five hours. At dawn, the energy temperatures at heat in the greenhouse. The energy and shade screens 25 to 27°C three reserve is used to provide heat during are opened and the cold air from the hours before sunset (warm evening). the early evening hours. upper levels of the greenhouse is mixed Optimally, three hours are enough to Later, the heating level is reduced to a with the warm air from the plant area. create enough energy reserve in the temperature that is still tolerated by the Minimum temperature limits are set to greenhouse for the early evening hours. plants. The greatest savings are achieved

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Energy-Saving Climate Control


protect the plants, but they are rarely reached. The lower temperatures in the morning have the additional positive effect of reducing elongation growth (internode elongation). Concerns that this effect could be eliminated by lighting with discharge lamps have not been confirmed in studies to date. However, the effect of supplemental lighting tends to be less in the morning than in the afternoon due to the lower temperatures. Because the heat radiation of HPS lighting increases the leaf temperature, some growers use their lighting to prevent water condensation during this period. Especially on sunny days, natural sunlight warms the air in the greenhouse. The heating is switched on only if the greenhouse is insufficiently heated after four to five hours. From an energy conservation perspective, it is not reasonable to heat the greenhouse during the morning hours, only to later give off the costly energy through the ventilation. However, the model must be adapted to the specific plants and regional conditions. In some cases, for example, it may be useful to provide higher heating temperatures in the evening hours and start the cool morning just shortly after midnight. Growers with high-tech equipment have the advantage of being able to set the heating and ventilation parameters individually. Energy or shade screens are additional options for reducing heating requirements at night. However, practical experience has shown that regular monitoring and maintenance of the sensors is necessary, especially if temperatures in the greenhouse are set at the limits. Dry cultivation supports the overall result. If watering is scheduled before noon, humidity does not increase unnecessarily in the evening. Regional weather conditions such as the hours of sunlight also affect the cultivation success.

Proven Success The model was developed at HSWT in 2008 and has been tested continuously. The Institute for Horticulture thus has many years of experience. Today, around 50 percent of growers in Bavaria (largest federal state of Germany with an area of 70.550 square kilometres) use the approach. The results throughout the past eight years have shown that by increasing

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Screens are open during a sunny day and closed in the afternoon to maintain the right temperature in the greenhouse, thus utilising much of natural energy.

the greenhouse temperature in the late afternoon (warm evening) and the systematic use of energy screens, heating does not need to be turned on until significantly later. At the same time, less energy is used for heating when the temperature is lowered in the morning, while achieving a nearly identical daily mean temperature (DMT). As tests have shown, between 25 and 80 percent of the energy normally required for heating was saved (Figure 1). For a greenhouse of 1 hectare, this results in energy savings of at least 250 MWh. Over the years, the model has been tested on nearly all relevant ornamental plants. The results show that these crops can be grown with no loss of quality. Figure 1 presents the energy savings achieved in a

few economically significant crops. As the model uses natural sunlight as a heat source, energy savings increase with the number of hours of sunlight. Interested growers should therefore first determine the hours of sunlight at their location.

By: Thomas Schwend

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Starting up a Cannabis Growing

Greenhouse System

The cannabis market is becoming increasingly appealing for growers. What considerations should be made before diving into cannabis cultivation?


o matter what kind of grower you are, there is no doubt that cannabis cultivation has been considered. It can be a difficult market to break into and several questions must have crossed the reader’s mind over the best practices for producing highquality cannabis and how to succeed in a market that is becoming increasingly competitive. What’s the first thing every grower should start with if they’re looking to get into growing cannabis in a hydroponics system? Understanding the marketplace and the actual price of the crop is important. A lot of growers think that no matter what they do, there’s going to be profits. This isn’t the case, and they must examine the marketplace they will be growing in. many people jump into it not understanding necessarily what the market is currently demanding. From a cultivation standpoint, environment is everything. Being able to control your environment is paramount in cultivating anything, but especially cannabis, so the producer must make sure everything is in place to control the environment and then build around that. When new markets open, the pattern shows that there’s a high cost per kilogram, which at the time can justify a lot of expenses for setting up a large operation, but growers must anticipate that the market will become more competitive. Prices are going to drop and they’re going to have to exist on thinner

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margins down the road. It makes sense to set up an operation in stages. Smartly phasing in producing and expansions can help maximize profits. For instance, by adding greenhouse bays one at a time. You can expand as you make cash, and that’s one of the smartest ways an operation can do it. Scaling up your greenhouse as production demands it is a smart way to go about it. Sometimes new producers invest in a multimillion Rand cultivation site that may or may not be profitable in a few years when the price per kilogram is half of what it used to be. That’s the trend often, so it makes sense to anticipate that. The producer can also do the same thing with automation. You can start producing now and capture the current market rate, while it’s still high, and then add things like automatic watering, computer control and climate irrigation. That can all be phased in over time as cash flow allows. It makes sense not to employ methods that worked in small-scale cultivation, which may have been born out of necessity, and try to scale it up as a commercial business. It’s never going to work. Growers should look toward practices used in modern, large-scale agriculture. A lot of waste is through misinformation and outdated growing methods. Most new cannabis growers are not utilizing university-level research to make decisions. Instead, they’re making decisions based on what YouTube or the

internet is saying. Growers should use analytical research to drive changes in the grow. It’s a more commercial approach, and it can help to avoid costly mistakes. Automatic irrigation systems are one of the least expensive and most time-saving units that is available. For a fair price you can have a completely automated watering system that delivers a precise amount. It reduces heavy watering and extreme drying, so it can be a good way to prevent disease. Also, you want to be able to efficiently move through your harvest. You want a perpetual harvest, where you have a separate space for clones and mothers, and then separate veg and flower rooms. By doing that you can cycle through and achieve a sustainable harvest. Every two weeks should be harvesting periods, while simultaneously taking cuttings and starting the process over again. You really don’t want to try and cram the entire workload into a couple weeks where you’re harvesting thousands of plants and need extra labour. With a perpetual cycle, you’re also providing products to customers on a consistent basis. An automated blackout greenhouse can increase profitability by not only creating a year-round grow space, but with the built-in automation, growers can also reduce labour costs. It’s a win-win situation. If you’re just producing starts for field production, probably not, but everybody else can benefit from an automated light fitted greenhouse. If you use a blackout system in a greenhouse, you’ll be able to control the photo period and get more turns a year. Therefore, profits are increased. Growers need to know the land area where they intend growing on. Also, with strong public law still in place dealing with cannabis, proper security by means of electric fences around the property would be necessary especially if located close to towns or suburbs. Adequate circulation and ventilation are necessary because it can maximize the crop’s growth rate and metabolism by controlling those factors. Growers should take this into consideration as is the best way to ensure high yields. By Chris Machnich

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Excellent turnout at Nampo for

Greenhouse Technologies Greenhouse Technologies exhibited at Nampo 2019 which was characterised by good weather and 81 345 visitors.


he Greenhouse Technologies exhibition was well attended by farmers and public who showed keen interest. The company is a thriving entity specialising in greenhouse-related products that includes greenhouse plastics, peat moss, coir, irrigation systems and Dutch greenhouse technology. One of the focus points of the Greenhouse Technologies exhibition was the irrigation solutions from Rivulis Irrigation, for which Greenhouse Technologies are the agents in South Africa. Feedback from visitors to the stand was very positive and with the Greenhouse Technologies’s team assisting visitors with valuable information on solutions in the industry, visitors left satisfied and informed. Be sure to visit their exhibition again at NAMPO 12 - 15 May 2020.

Turnkey solutions “Our first warehouse opened in City Deep, Johannesburg at the Multi-Flora Market in 2007 and has since grown and expanded. Today we are known as one of the market leaders in the greenhouse film and grow media industry with more than 30 employees nationwide,” Francois de Kock, director of Greenhouse Technologies proudly explained. Products on offer to the Agricultural industry include Greenhouse Film/Plastic - where the company offers a variety of greenhouse film with different properties in answer to all the growers’ needs. Another fantastic product is Coir (Coco Peat), which has now become a standard grow medium in the industry. It is a 100% organic medium and can be used to improve the structure of the producer’s growing medium. Greenhouse Technologies’s irrigation systems are imported from Israel using Rivulis company. Rivulis provides a wide range of agricultural products including drip lines (brown & green), Supertif button drippers, filters and valves. According to Francois they also supply Peat moss imported from Lithuania. The world’s leading Peat Moss manufacturer, Klasmann-Deilmann is the company whose brand is on offer from this country. All these products are certified and tested off-site and arrive at Greenhouse Technologies ready to be applied. The Peat Moss is tested in Lithuania, but the CoirCocopeat is imported from India (where each container has been tested) and greenhouse covering film is imported from Israel. “At Greenhouse Technologies, we make sure that the factories where our products are manufactured have done all the necessary tests before products are imported, to ensure the quality and most importantly to maintain relationships with our foreign investors.” “What makes our company unique is that we go all out to offer our clients the best possible product for their individual needs. We pride ourselves on customer satisfaction – a sale doesn’t end at point of sale, the after service is just as important,” Francois confirms. When it comes to growing produce in a greenhouse, Greenhouse Technologies offer an end- to-end product solution that ensure clients the best possible service, with the best possible results.

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How Do Flowers Absorb Dye? Many people are familiar with the concept of dyeing flowers with food colouring. But did you ever stop to think about the underlying process that occurs when you dye flowers using just coloured water? The structure of the plant and natural processes like transpiration and cohesion enable many flowers to readily absorb the food colouring and deposit the dye on their petals. Dyeing Process hen a cut flower is placed in dye, the dye is pulled up the stem and absorbed along with the water. As transpiration causes the water to evaporate from the leaves, the dye is left behind on the petals. The entire dyeing process can take anywhere from a few hours to a few days, depending on the conditions, the flowers and the dyes.


Transpiration The process of transpiration refers to the evaporation of water from a plant’s leaves. Most of the water inside of a plant is eventually lost through transpiration. The loss of water through the leaves creates low pressure in the leaves, which leads the plant to pull more water up through the stem, much like a straw. Once the water begins to travel up the plant’s vessel system, cohesion causes the water molecules to stick together and continue to move up the stem. Flowers White chrysanthemum and carnations are generally the two flowers most recommended for dyeing, although any

long-stemmed flower will work. Chrysanthemum petals can be dyed completely; carnations typically display the colour of the dye while still maintaining a little whiteness on the petals. Whichever flower you choose, the dyeing process Carnations easily absorb dye will be most successful if you select a fresh makeup of the dye, White chrysanthemum flower, rather than one while different brands and carnations are that is in full bloom or of food colouring generally the two flowers also affect the rate wilted. most recommended for Factors of colour absorption. dyeing, although any Experiments indicate The dye works best that blue dye is most with very warm to long-stemmed flower effective, followed hot water since heat will work. by red dye and then acts as a catalyst. green dye. Similarly, warmer air Tips temperature will also speed up the water absorption and dyeing process. Recut the stem diagonally under Different colour dyes seem to work water before placing the flower in at different rates due to the chemical dyed water. This encourages the flow of water up the flower stem and prevents any air bubbles from forming at the base of the stem. Florists suggest adding a floral preservative to the water to extend the life of your flowers as you dye them. Experts also recommend using 30 to 40 drops of food colouring in order to achieve the desired colour. By Stephanie Smith

Whichever flower you choose, the dyeing process will be most successful if you select a fresh flower, rather than one that is in full bloom or wilted.

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Agbiz’s reaction on the SONA “In these tough economic times, it was refreshing to hear President Ramaphosa’s recommitment to placing South Africa’s economic growth at the forefront of the sixth administration’s agenda,” an Agbiz spokesperson said.


change mitigation and adaptation, water infrastructure and increasing the pace of technology adoption across the globe. These factors could affect the growth and competitiveness of the South African agricultural sector in the global markets.” While an increasing focus on the issues is encouraged, the lack of clarity regarding the land reform policy framework remains a concern to South African agribusinesses. “We note the progress made regarding the report of the Presidential Advisory Panel on Agriculture and Land Reform and look forward to engaging with its content and focus once it is made public. We will continue to engage with government in various fora on crafting a sustainable solution to land reform in South Africa that is based on the principle of public-

private and community partnerships as envisioned in Chapter six of the NDP.” “For the agricultural sector to thrive, South Africa not only needs to boost production, but also increase access to the export market, and we were pleased that the president acknowledged the importance of export-led growth in the sector. While we like the tone of the president’s speech, we remain cautiously optimistic as the challenges facing South Africa today will require a greater commitment to action than ever before. The focus must now be on the how, so providing detailed content to the broad policy direction and implementation will be key. Agbiz will continue to engage with various ministries and SOEs over the coming months.”

optimise nutrition in a free-draining system. The procedure starts with a chemical analysis of the root zone solution. One fresh sample from the drainage tank in a closed system, or a mix of 20 fresh sub samples, taken from growing bags in a drain-to-waste system, should be analysed at least monthly. Since changes in the ammonium: nitrate ratio may occur during storage, these samples should be analysed as soon as possible. Apart from regular pH and

EC checks, root zone analyses are used to detect deviations from pre-set root zone norms, thus, allowing the plants to communicate with their growers. Before this can be done, the EC and nutrient levels of the sampled solution should be adjusted to match the EC of the norm solution. This procedure is described in a book: ‘Nutrient solutions and Greenhouse management’ only available from Dr Nic Combrink: E-mail: njjc@sun.ac.za.

e were also pleased to hear the president’s re-emphasis of the need to implement the National Development Plan (NDP) and the country’s commitment to vision 2030. In this vision, the agricultural value chain plays a crucial role in the growth and stability of rural economies.” Agbiz has long supported and argued for the implementation of Chapter six of the NDP over the past few years as it is the roadmap to inclusive growth in the sector and will address the triple challenges of poverty, unemployment and inequality. “We are encouraged by the president’s pragmatism regarding contemporary issues facing the agricultural sector such as climate Prevent the accumulation


The laboratories send technicians to take root zone samples every week or two. The results and suggested changes to nutrient mixes are E-mailed to the growers the following day. The duplication of such a system under South African conditions may be impractical at this stage, but the same principles may be adapted to improve our nutrient managerial effectiveness. A Root zone analysis is a must for recycling, but it can also be useful to





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