Undercover
farming
ucf
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maY/JUNE 2020 Volume 17 No 3
I I R45.00 per issue
FLOWERS
CANNABIS
SWEET PEPPERS
CUCUMBERS
Gerbera producer manages during Covid-19 Page 4
Cannabis produced in cocopeat-perlite media Page 8
Sweet peppers - fine-tuning the growing process Page 9
Cucumbers - fertilizing tips for optimal success Page 17
Undercover growing solutions to help your business flourish
Turnkey Solutions
Greenhouse Structures
Irrigation
Cape Town
Climate Control
Crop Management Technology
Growing Products
Johannesburg
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021 987 6980
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011 974 5254
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Vegtech, 25 Kiaat Road, Kraaifontein
Address
Vegtech, 23 Brewery Street, Isando,
Industria, Cape Town, 7570. Email
info@vegtech.co.za
Johannesburg, 1600. Email
www.vegtech.co.za
info@vegtech.co.za
greenhouses I shade net I hydroponics I aquaponics PROPRIETOR I ADVERTISING SUZANNE OOSTHUIZEN 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 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.
Contents 4
Gerbera production prevails over Covid-19 at Imbali
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Producing perfect greenhouse tomatoes The advantages of growing cannabis in coco-peat perlite mixture
9 Sweet peppers: how to produce a superior product 10 New country manager for pma South Africa 13 Tasting a tomato without destroying it 14 Thrips control in the greenhouse – be sssertive 16 Keeping the balance in cucumber production 16 Subscription form 17 General fertilizing principles for cucumbers 19 Youth harness the power of climate-smart
FRONT PAGE: Tania Henkel, manager of Imbali Cut Flowers amongst her Gerberas.
INSIDE ...
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agriculture with aquaponics
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A Scripture for the now ...
The Lord is my Rock, my Rescuer, defence and fortress. Why then should I be tense with fear when troubles come? Psalms 62:2
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‘
o many things to do; and so little time to do it in.’ Remember these words that you must have spoken during your life? All of a sudden a strange phenomenon gets grip on the whole worlds’ business system, finance and capital markets, employment and greatest of all, our human capital. Precious lives are destroyed, families brokenhearted and businesses lost staff at almost all levels, over and above that they were ordered to close. By now, reading this you would think I am just re-iterating what has been repeated on TV and newspapers over and over. How did our greenhouse producers fare? Those with access to foreign markets were possibly able to get some stock out before lockdown at harbours and had to cold-room the rest? Workers had to be laid down and office staff put on leave. Supplies to stores eventually were able to be delivered but the customer queues grow longer by the day. Our main feature is about a brave young lady who managed her father’s business well during lockdown but is now back in business during Stage 3,– although one of her highlights is Mother’s Day, which all the cut flower farmers sadly missed; largely as it is a time to make ends meet in an already poor economic climate. About climate; the winter on the Highveld and various other parts of the country set in severely. With coal prices so extremely high, it is difficult to keep growing temperatures at an even keel while also having to look out for leaf diseases on plants. We are, by the look of things almost over the middle of winter and hopefully high temperatures will set in and if temperatures rise, so will production stabilize and stores have ample supplies. Our greatest hopes are however, pinned on a speedy reduction in Covid-19 cases and more-over, loss of lives. From Undercover Farming team we urge you to keep warm, keep the distance and offer assistance to whatever cause for those in dire need for nutrition and warm clothing. We endeavor to have more positive news in the next edition but hope the contents of this edition will be of advantage and interest to you. Soon we will all have ‘much to do again with little time to do it in’!
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It is said that Gerbera flowers are the fifth most popular flower in the world, according to the Flower Shop Network. Though, popularity of a specific flower type may vary from time to time, like for instance in South Africa, and growers have to find new strategies to keep themselves in the market.
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he current situation caused by Covid-19 pandemic, caused serious impact on flower growers as well. Multiflora Flower Market closed when the lockdown officially started. Imbali just stopped sending flowers because almost all the flowers were thrown away. It is the first time in the Henkel’s Gerbera history that they missed auctions. When flowers are offered to the Johannesburg Flower Market and it does not sell – for a variety of reasons – the Market raises a levy against the grower to cover the handling and discarding of the bunches. Imbali Cut Flowers, owned by Marcus Henkel and for the past six and a half years managed by his daughter Tania, is by no means a mega operation, but quality and consistency is guarded over their production of Gerbera flowers. When Marcus started out on the farm near Olifantsfontein, he constructed a greenhouse for Gypsophila but as its market declined sharply, decided to invest in another flower type. He then, after much research, resorted to growing Gerbera flowers for which there was a steady market. gets to the plants via a dripper system, “Tania explains. More greenhouses were added and the latest one and biggest is a Richel structure Gerbera flowers are grown to have a fitted with screens. This brings the total preferred length and our goal is at least of greenhouses at Imbali to seven. The 50cm. The flower must face upwards land purchased by Marcus at the time is and all petals intact. There are different on dolomitic structure but the borehole varieties of the flower which have three he drilled, offers year-round good quality to five layers of petals and also some and quantity water. Of whose crowns appear recent, with industrial smaller. Gerbera flowers Imbali just stopped activity and an informal are known for their sending flowers because settlement in the vivid and variety of almost all the flowers were colours which, in a vase vicinity, they risk the thrown away. It is the reduction of water or bouquet immediately quality. first time in the Henkel’s catches the eye. “We do not grow Currently, after a Gerbera history that they our own seedlings number of years missed auctions. as they are patented being one of the most and therefore import sought-after flower types, the demand un-rooted material from our Dutch for Gerbera in South Africa decreased source. Our plants are then grown in to a certain extent. Although, according cocopeat (from Sri-Lanka) mixed with to Tania with their participation at Perlite. The plants are in separate pots the Africa Flower Show at the Mall of on stands and fertigation and irrigation Africa in Johannesburg, Imbali Flowers’
Gerbera production
prevails over Covid-19 at Imbali
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Above: Inspection of Gerbera plants by Imbali Cut Flower staff is a daily routine as any pest or insect could strike. High sanitation standards are followed in all greenhouses. Left: Tania Henkel, manager of Imbali Cut Flowers amongst her Gerberas.
Gerberas played a part in the initiative to increase interest by public in cut flowers. The production on Imbali farm varies dramatically between Spring and Winter; during Spring up to 20 000 stems are sold on the market but in Winter the figure drops to around 3 000 stems. Planning ahead is a daunting task – the swing in market demand comes suddenly and Tania has to read the market tendencies daily and order basic requirements such as packaging, buckets and small odds and ends of packaging in time to reach them to answer to the upswing demand. “We have been hit hard by the governments’ lockdown regulations,” Tania said. She employs a staff of 22 people of whom 14 stay on the farm. She gave staff the option of spending the lockdown with their families. Anyone who lived on the premises and chose not to go home were put on a roster to work through April to keep the farm running. Those who did not live on the premises were not allowed to work. As in the case of many other businesses that was globally financially affected, the lockdown period had proprietors and staff put their thinking caps on to become creative in their marketing to capture additional markets. Imbali also now sells
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direct to clients owning outlets or that have a demand for Gerbera flowers. Gerbera flowers with long stems are in demand by florists and therefore with correct temperature prevailing, business is fine. During winter the stems grow mostly shorter, but Tania is of opinion that the shorter stem flowers should sell very well for smaller bouquets as gifts or for use in wreaths. The client pays the long stem price, but after the bouquet or smaller gift is completed, much of the stem is lost – which was paid for. This is another aspect Tania endeavor to address to market her short stems Gerberas directly. A Gerbera plant is expected to produce optimally for four years but should you keep it in your system for longer, less stems are produced by
the plant. Tania ordered plant material which will have the plants produce for six years but with Covid on hand cannot import her new plant material as yet. If regulations lift she hopes to plant her greenhouses with the new material before the end of the year. Some of her plants are eleven years old and still flowering but she insists on cleaning greenhouses out with old material or mixed with newer plants and plant completely new material in all her greenhouses. She had new material planted late last year and the first production from these started flowering a few days after lockdown began, so never made it to the market. These were all destroyed as the Flower Market was closed. “The worst of all was that the first flowers on a Gerbera plant always are the best and most beautiful! I have shown some to a florist who was filled with awe over this precious masterpiece, but, alas it was destroyed,” Tania explained, rather horrified. The investment in new Gerbera plant material, cocopeat and Perlite, which are all imported commodities is huge and with the exchange rate as it is now, takes careful planning. At the same time, while everything else on the production site is in place, the producer is hit hard by a disaster such as the current one. Temperature for Gerberas to flourish is around 23 degrees Celsius. There is a boiler on the farm but the price of coal
Spraying against various pests are done regularly because the vivid colours of the Gerberas attract various insect pests. This method ensures higher production efficacy and less loss in flowers.
became too excessive to run it. According to Tania her winter climate on the farm is minus five this year but she is positive about the colder temperature this year as it also kills harmful insects. Red Spider Mite is their current biggest problem, but in 2018 they experienced the worst White Fly breakout that professionals in the industry had ever seen. They were waiting for the normal cold to set in and didn’t perform special sprays so as to save the health of the plants assuming winter would sort the pest problem. However, it did not get cold enough, with dire consequences. Tania is holding 7
This greenhouse is the largest and latest addition to increase and sustain production of Gerbera flowers at Imbali Cut Flowers.
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Developing new tomato varieties for controlledenvironment production is a huge area of focus for commercial breeders. Many of them have established breeding programs specifically centred on greenhouse varieties. After all, while some fruit traits may be similar whether a variety is grown indoors or outdoors (taste, appearance, etc.) there are other requirements that may be much different for greenhouse-grown tomatoes, including light sensitivity, vigour, and pest susceptibility.
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ccording to specialists in the field, the best varieties for greenhouse production come from breeding programs where the parental lines are pre-selected in those conditions and are used in a crossbreeding schedule to breed new material. On top of this, breeders also must find the right balance between what growers might need versus what retailers or consumers are asking for. The tomato producer’s goal is to deliver the tastiest tomatoes and develop varieties that will make consumers happy, while also meeting the needs of packers and retailers. The definition of a good variety will be different for each of them, which makes it a challenge for seeds men and growers.
Predictability and Uniformity The question is; how can growers decide which varieties are best for them? Globally, a current key topic concerns farm labour and its effect on costs. A grower’s daily concern is going to be labour, according to all producers. Although the producer wants a crop
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Producing perfect greenhouse tomatoes that is going to offer quality to the end that same vigour level, the producer will consumer, they also need a crop that experience too much growth. is easy to grow, will offer a predictable It is agreed that greenhouse growers will performance, and will be easy to manage. have higher fixed overhead costs, which Uniformity and consistency are important will have to be factored into the cost of as growers are looking for a product growing the plant. Before one tomato that will have the same size, shape, and quality regardless of conditions. When it comes to varieties developed for greenhouse production, there are other factors growers will have to consider, including vigour control. When breeding a variety for field production, breeders need to build more vigour into the plant because of the increased environmental, pest and disease pressure face with by growers globally. There’s more protection in the greenhouse, Even-sized tomatoes grown in a greenhouse with proper so if one pushes management.
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step for growers of all sizes. Seed suppliers suggest running seedling is planted, the farmer needs to cover the costs of his trials in cooperation with the seed supplier, as they can provide structure, irrigation system, and heating systems. Therefore, guidance based on their extensive trial databases. If the final trial growers need to be confident from the very beginning that they results are not overly exciting, that’s where discussions with the are making the right choice. breeding companies come into play. Once the grower is going to add a variety, he has to be Together, growers and seed companies can determine what else absolutely convinced that it’s the right variety, that there is a may be in the variety that, in further experiments, may be able market for it, and that it will work in his greenhouse system. to improve results. When the farmer knows the seed got the The producer must also display confidence in the genetics and combination of characteristics and traits it means he can grow a the experience the breeder has had with that variety. consistent crop with great marketable yield There are a number of other factors growers through the life cycle of his or her crop. Once the grower is going need to consider, including plant habit, required to add a variety, he has to The role of flavour fruit size based on market segment, and yield indicators, including speed of cluster In recent years, much of the work that goes be absolutely convinced development, how well the flowers are setting into trailing on which varieties work best for that it’s the right variety, fruit, how many flowers on a cluster, speed of that there is a market for it, greenhouse production has shifted from the flowering, and percentage of setting. university to the breeder level. However, and that it will work in his there are universal factors that need to be The grower should work with the seed greenhouse system. considered. company and his seedling supplier to select indeterminate materials, which offer Flavour attributes need to be at a higher continuous growth, as compared to a determinate variety, which priority than they have in the past. Many excellent tasting will stop growing after a certain amount of time to extend his varieties have been discontinued and are no longer available production period. because they were better in some other traits. Yield is and will be important as long as produce is sold by weight but selling Getting to this point requires a great deal of cooperation large-yielding varieties at the expense of poor taste is a longbetween the breeder and the grower. While growers need to range, serious mistake. It causes loss of return customers and be in communication with breeders, it’s a two-way street, as breeders need to know about the challenges growers have faced sales to drop off. in the past, and how much their supply chain customers are Producers of new varieties who also notice new growing dictating what they should be growing. techniques in greenhouses reckons cracking is rare in greenhouse varieties today, and disease resistance excellent. The easiest way to determine how a variety is performing is through a trial. Performing trials in the greenhouse is a necessary By Brian D. Sparks Gerbera production
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out during this winter and still sprays to guard over the plants. There are four major pests and diseases on Imbali farm and Powdery mildew was at the top of the list, but by introducing an IPM program, it struck the disease to fall to fourth on the list. White fly almost ruined the production of the Gerberas and Tania had to do much research on the insect and how to combat it but has it under control. Leaf miner is third on the list and alternate with Red spider mite according to cold or hot temperatures. The Red spider mite is controlled with spraying but, since it is resistant to most chemicals, spraying only serves to reduce the population but not get rid of it. Evidently, according to Tania, the Netherlands was much against excessive spraying overall for Red spider mite, but currently also resort to spraying as they experience a high percentage of this pest on their plants. At Imbali they would like to introduce predators to combat insect pests but the products on the market will not control all four pests, therefore they still have to spray. Tania managed to build up an integrated IPM program which contains substances that will control the pests. She still has to control Whitefly and Red Spider Mite chemically however, as it is quite resistant to biological control. Producing Gerbera flowers year round while obtaining the best quality and stem length is quite a balancing act the producer has to perform. Here, water quality, a fertigation program calendar, regular plant inspection and pest control and greenhouse sanitation on a daily basis are aspects which must come as natural as breathing. Surrounding you with specialists in the fields of growing mixtures, fertilizer and pest control as well as marketing is a must to become successful.
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The advantages of
growing cannabis
in coco-peat perlite mixture Coco-peat is especially suited for growing cannabis because it is difficult to over-water when growing cannabis in a coco-peat perlite mix. The coco-peat perlite does not retain water in the same way that soil does, so excess water drains away.
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ver-watering is possibly the most common mistake new growers make. To understand why overwatering is such a big problem when growing cannabis, keep in mind the wet-dry cycle. Because it is lighter than soil and holds more oxygen, root development is usually faster and stronger than growing in soil. Because coco-peat doesn’t hold water, you have more control over the nutrients you give the plant. The plant’s roots receive only those nutrients it receives at each watering cycle and excess drains away. This makes issues of over-fertilization less likely. If you do experience a nutrient overload, you can flush the material through with large amounts of plain pHd water to wash unnecessary residual out. If you see a nutrient deficiency it is easy to increase the feed strength. In this way it is like a “light” version of growing hydroponically without the expense of a hydro kit. If you are growing cannabis using LED grow lights, coco-perlite makes the perfect growing medium. When you grow cannabis under HPS grow lights, the high temperature of these lights increases the surface evaporation of moisture from the soil, thus speeding up the wet-dry cycle. As this is not the case with LED grow lights, plants grown in soil often suffer from a lengthy wet/dry cycle, leading to sodden roots, lack of oxygen and possible EC build-ups. • Coco-peat is more environmentally friendly than plain peat soil. • Coco-peat is not a good environment for pests to thrive in.
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• It is rot-resistant. The disadvantages of using coco-peat – perlite mix with cannabis. 1. More watering days. 2. Strict pH control is essential. 3. The plant is more reliant on you to supply its needs. 4. More attention needs to be given when choosing nutrients. A bit of advice that came from experience: • If you have a few successful cannabis growing seasons behind you but wish to do better – or because you have grown in soil and encountered problems, invest in a perlite –cocopeat mixture. • You need to understand the wet/dry cycle. • Use a pH pen to test, properly calibrated and use it at every watering cycle. Strips are not good enough – buy a pen. • You must be prepared to spend money on nutrients; recapture it in your ROI. • Best is to grow in grow bags or pots, either under lights or a greenhouse with ample sun. Mixing the coco-peat and perlite to make a growing medium Before mixing you must first ensure that your coco-peat is clean. It depends on your source of coco but some is produced using seawater as a flush. To be safe, flush the coco three times with fresh water (to rinse out any residual salt etc). Mix 50:50 by volume with perlite. Do not be tempted to add anything else in the grow mix. How would you know how much to feed
Perlite on its own.
after that? You are not finished yet though. Fill a pot with the mix and bleed some pH 6 water through until you are getting runoff. Collect some of the run-off and test its pH. If necessary, continue flushing until the run-off is consistently similar in PH as the water going in. The pH of the growing medium of cannabis is crucial at all times. Be sure to check your plants regularly for any form of deficit and act accordingly. R Bergman
Coco-peat and perlite mixture.
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Sweet peppers: how to produce a superior product Sweet bell peppers are high impact superior products primarily grown in three colours; red, yellow and orange. No matter what the final colour of the pepper, all sweet peppers start out green in colour and the final colour develops as the fruit ripens.
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he colour of the mature pepper is determined by the cultivar grown. Harvesting the fully sized peppers when they are still green is not profitable as the mature coloured peppers command a better price. Greenhouse pepper production is based on a full year cycle. The transplants go into the production greenhouse in approximately mid-July to September at 6 weeks of age, the first pick of fruit begins in November and last to April. The greenhouses are empty for only a few weeks during the year to allow for the removal of the old crop, the thorough cleaning of the greenhouse and to set up the greenhouse for the new crop. One crop a year is grown, that is, production for the entire year is based on the same set of plants. As it takes approximately 20 weeks (4 months), from seeding the crop, to first pick as a result, growing more than one crop a year is not considered profitable.
Ripening red sweet bell pepper.
When considering the cropping cycle, it is not recommended to carry a fully producing crop over the month of May. The reason for this is that the lower winter light levels do not support profitable crop production. This is also the reason why August is usually the month when crops are pulled and the new crop goes in. The prices received for the crop in the winter months are always higher than in summer when the greenhouse produce competes with the field produce. Winter production would offer considerable price advantage for produce if the yield and quality of the fruit were maintained. As crop production techniques improve, running a producing crop over the winter months may prove profitable if the
Yellow sweet bell pepper.
production capacity marketed covers the expense of heating resources. An approximate target yield for intro ductory growers would be 23 kg/m². Sweet bell peppers are grown as a tall crop, and provisions for working a tall crop must be incorporated into the greenhouse in order to grow the crop successfully. The main structural consideration for greenhouse sweet pepper production is the height of the greenhouse, the gutter height. A minimum recommended gutter height for sweet peppers would be 3.9 meters and the trend in greenhouses is to build them taller, with some greenhouses coming in at 5 meters at the gutters. The overhead support wires that support the weight of the plants are generally .3 meters below the gutter, and this serves as an approximate limit to the crop height. Having high gutters essentially allows for a level of “forgiveness” in pepper production. If the plants become unbalanced during the production cycle, and put more resources into vegetative production, they can grow taller in a short period of time. With higher gutters growers are able to bring the plants back into balance without necessarily have to worry that the crop will reach the roof too early in the crop cycle, resulting in early termination of the crop.
Cultivars Selection of greenhouse sweet pepper cultivars is dependent on colour, disease resistance, performance and 10
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New country manager for pma south africa
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roduce Marketing Association (PMA) has appointed Lianne Jones, a produce and floral industry veteran with extensive global experience, as the new Country Manager for PMA in South Africa. Jones’s background includes nearly 20 years of marketing, sales, category management, account management and business development with companies such as Zespri International Limited, the Chilean Fresh Fruit Association, and Asda/International Produce Ltd., a U.K. subsidiary of Walmart. As PMA’s new Country Manager in South Africa, Jones will focus on providing member value, attracting and retaining members, and building strategic partnerships to help grow the produce and floral industry. She will oversee all PMA events and activities in South Africa, including Fresh Connections: Southern Africa, PMA Fresh Talks initiatives, and will support execution of Lianne Jones Fresh Summit, PMA’s annual convention and expo which takes place in various locations in the United States. She will also serve as PMA’s primary liaison with members, government agencies and other stakeholders in Southern Africa, as well as PMA’s South Africa Country Council. The council is comprised of industry leaders from across Southern Africa’s produce and floral supply chain. “Lianne knows the European and South African produce industry well, has strong contacts with South African retailers, and her approach to developing new market opportunities, as well as her experience in talent development, make her a great fit for PMA,” said Anouk Sijmonsma, PMA’s global regional vice president (Asia, Africa, Europe and Australia/New Zealand). Lianne’s background as an international marketer will help position PMA to support these goals, provide member value and growth.”
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yield. A variety of seed companies and distributors offer greenhouse sweet pepper cultivars, and the “latest” cultivars are always subject to change when superior cultivars are developed.
“House-set’” transplanting into the production greenhouse.
Before selecting cultivars, investigate what is currently being grown by the industry in your area as the suitability of cultivars can vary depending on region and obviously, your markets’ demand. It is also not recommended that more than one colour of pepper be grown in the same greenhouse unless they are grown in separate environments. The cultural requirements of the different cultivars can be distinct enough to require that the environments be managed differently in order to obtain maximum yield.
Orange sweet bell pepper.
Young sweet bell pepper developing towards full size and eventual mature color.
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Planting density Before the young plants are transplanted, the production greenhouse is set-up to receive the plants. A planting density of 3 to 6 plants/m² is recommended. Plants are normally trained with two stems per plant (“V” system), which gives about 6-7 stems per meter To determine the number
of plants required for the greenhouse, multiply the production area (meters) by your desired plant density. The standard pepper grow bag 1 meter in length has an approximate volume of 16 - 20 litres when full. The number of rows can then be calculated. Knowing the number of bags required and dividing this number by the number of rows, you will arrive at the number of bags required per row required to reach the target plant density. The number of bags in a row is spaced out evenly along the length of the row.
Transplanting into the production greenhouse; “house-set” The young plants are ready to be transplanted into the production greenhouse at 6 weeks of age. The plants should be approximately 25 cm tall, have about 4 leaves on the main 11
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the rootzone E.C. can be allowed to rise to about 4.0 to 4.5 mmhos, as the season progresses and light levels begin to improve, the rootzone E.C. should be brought down to 3.5 to 4.0 mmhos. One week after house-set target day temperatures of 21°C and night temperatures of 16 - 17°C for a 24-hour average of 20 - 21°C. The optimum temperature for vegetative growth in peppers is between 21 and 23°C and for yield about 21°C. Establishing the difference in day/night temperature, while maintaining the target 24-hour average temperature, directs the plants to set flowers and maintain enough vegetative growth required for optimum fruit development and yield.
Pruning and plant training Pepper plants are indeterminate plants, that is, they continually grow new stems and leaves. For this reason the plants have to be pruned and trained on a regular basis in order to ensure a balanced growth for maximum fruit production. Pepper plants are managed with two main stems per plant, resulting in a density Young plants rooted well into the bag, two weeks after transplanting. of 12 stems/m² from an initial planting density of 6 plants/m2. Pruning also stem and will have begun to branch. made to allow for complete drainage of improves air circulation around the plant The main stem usually branches into 2 the bags and to avoid “pooling” of the which helps to reduce disease. to 3 branches, the point of branching is feed solution at the bottom of the bag. Plants are generally pruned every two sometimes referred to as the “fork”. For the first week in the greenhouse the weeks. As new leaves and lateral side Examination of the underside of the day/night temperatures are maintained shoots develop from the axils of the rockwool blocks should reveal a number at a constant 20 - 21°C, target a relative new nodes on the growing stems, they of roots beginning to develop through humidity of 70 to 80% ( VPD of 3 to 5 have to be pruned to maintain the two the bottom of the block. This is another gm/cm³). Maintain CO2 levels at 800 to main-stem architecture of the plant. The indication that the plants are ready to be 1,000 ppm. pepper flowers also develop at the nodes. transplanted onto into the greenhouse The primary goal at this stage of the A node is defined as a point on the stem to allow the roots to “knit” into the production cycle is to establish the young from which leaves arise and the length of growing media, for example, coco coir or pepper plants on the stem between nodes is rockwool slabs. media and ensure that The primary goal at this called an internode. The The growing media should be wetted, or they develop a strong term “axil” refers to the stage of the production “conditioned” with nutrient feed solution root system. Generally upper angle formed by cycle is to establish the (E.C. 2.5 - 3.0 mmhos) for 24 hours speaking, if the plants the junction of a leaf (or young pepper plants on lateral) with the stem. before the plants are set onto the media. do not establish strong The general rule is to condition the media roots early, when they the media and ensure After about 1 week with feed solution at the same E.C. as are quite young, they will that they develop a in the greenhouse all exists in the rockwool block. It is also not develop a strong root the plants will have strong root system. important to ensure that the media is at system later in the season developed 2 to 3 stem 20°C, and that this root zone temperature once the focus of the shoots at the fork. At this point the is maintained throughout the remainder of plants shifts towards fruit production. plants should be pruned to leave the two the growing season. Careful attention should be paid to the strongest stems. These two stems will be The plants are then set onto the media application of the feed solution, target managed to carry the full production of ensuring good contact between the a 5% overdrain. Overwatering at this the plants throughout the year. Each stem bottom of the rockwool block and the point will hinder the development of a will grow to a height of up to 4 meters growing media. If cocopeat bags are strong root system, resulting in a root and require support in order to remain used as the growing media, six plants system that will not perform well under upright. Twine hung from the overhead are grown per 20 litre bag and the bags the intense light conditions in the coming support wires is used to support each are slit to provide drainage. The slits summer months. Increase the amount of stem. are approximately 4 cm long, and are nutrient solution delivered to maintain the The twine is tied to the main stem about made on the sides of the bags facing the 5% overdrain target as the plants grow 30 centimetres up from the block, one drainage channel, with one slit placed larger. length of twine per stem. Ensure that the between each of two plants. The slits are Maintain a feed E.C. of 2.5 - 3.5 mmhos, twine is not tied too tightly to 12
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the stem or the stem can be damaged as it expands. One other approach with the twine is to lay the twine on the grow bag just before transplanting the plant onto the coco coir. As the plant roots into the coir it secures the twine. Enough slack is left in the twine so that it can be twisted around the stem as it grows and develops throughout the year. Early in the season the plants are pruned to one leaf per node, that is the main leaf at the node is allowed to develop and the lateral stem developing from the node is removed. Beginning in October, a second leaf can be left to develop at every node on the main stem. The lateral stem is allowed to develop to its first node, at Flower and fruit set. which point a leaf develops as well as another secondary lateral stem. occur with a resulting reduction on fruit it is important to know when to target The secondary lateral stem is pruned out, set. Fruit set is known to be reduced at the first fruit set and start to establish the leaving the first leaf on the original lateral balance between stem and leaf production temperatures above 27°C and by low stem as well as the primary leaf on the relative humidity. There is also evidence and fruit production. main stem. The reason for leaving this of progressive reduction in fruit size The presence of fruit will reduce second leaf is to increase the leaf area of associated with increasing light intensity vegetative growth as the balance is the canopy to both make better use of during the high-light summer months. established. Pruning and training of the increasing light levels and to provide Shading the greenhouse can offset some the leaves and stems then allows for shade for the developing fruit. of the effects of high light intensity during matching the vegetative growth with fruit Care has to be taken when pruning the summer months, using a 10% shading growth. Once this balance is established to ensure that the main stem is not about the beginning of December. it is important to work to maintain the “blinded”, that the growing point of The hot summers make it nearly balance for continual, steady production the main stem is not pruned out. If this impossible to maintain the optimum throughout the season. occurs the main stem will not develop day-night, and 24-hour temperature Fruit set is increased by low temperatures any further. The main approach to avoid targets without the use of some form of but, fruit development may be affected blinding the main stem is to allow the evaporative cooling (pad and fan or mist by pollen infertility. The day/night lateral to develop 1.5 to 2.0 centimetres systems). However, the plants generally temperature difference can be used to before pinching it out. This do not have trouble continuing to set direct the plant to set allows the lateral to be Care has to be taken flowers under these conditions. Stressful flowers and fruit, while clearly identified an makes summer conditions direct the plants to when pruning to ensure the 24-hour average it easier to be very clear remain generative and can push the plants temperature can be that the main stem is on what is being removed to be too generative. used to ensure proper to ensure that the main not “blinded”, that the The plants have to be managed to fruit development in the stem growing point is left growing point of the maintain adequate leaf cover and balanced shortest time. intact. main stem is not pruned fruit load, by leaving more leaves on Pepper flowers are It is important to keep out. If this occurs the the plants and targeting about 6 fruit small under high the pruning current with per stem. If too many fruit per stem main stem will not night temperatures, the development of the are allowed to set, and the plant is not develop any further. where under low night plant. Once pruning falls directing adequate resources to leaf temperatures they behind, there is really no development, the plant will “stall” and are large. The formation of malformed catching up without sacrificing some yield, will not be able to fill the fruit, resulting in fruit is associated with problems with as too much of the plant’s resources were yield loss. temperature during pollination. Flattened allowed to go into undesirable leaf and Maintaining the root zone temperature fruit or “buttons” indicate insufficient stem production. at 20°C is also very important for the pollination as it is associated with the Pruning is done using the fingers or small establishment of the plant balance. Lower development of very few seeds per fruit. scissor cutters to ensure precise removal root zone temperatures (approximately The functioning of female flower organs is of the laterals and avoiding any damage 15°C) direct the plants to remain inhibited at low night temperatures (14°C to the main stem or main stem growing vegetative, and increases flower abortion or less), which gives rise to flattened fruit. point. When pruning the plants ensure and abortion of young fruit. optimal hygiene in order to avoid diseases. Pointed fruit which develop to a similar Abortion of flowers and fruit is related to size as normal blocky fruit, are probably Flower and fruit set the rate of production of photosynthetic a result of an imbalance of pepper plant The primary goal in managing the young assimilates and the distribution of growth regulators (hormones) in the pepper plants is to establish a strong assimilate within the plant. The number developing fruit. At high temperatures, vegetative plant on the bags. However, of flowers and fruit creates 32 to 38°C, elongation of the style can 13
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One of the most important properties of a fresh tomato is its taste. But how do you quantify taste? Breeders are very interested in that question. For the answer the taste model of Wageningen University & Research (WUR) or a taste panel can be used. The Greenhouse Horticulture Business Unit at WUR is investigating whether it is possible to map the taste remotely with a camera.
Tasting a tomato without destroying it
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he Fresh on Demand project is working on quality improvement in the fruit and vegetable chain, in order to better meet the wishes of consumers. Taste is an important variable. There are roughly three options for measuring this: in addition to the taste model and a taste panel, these are sensors. They can, for example, measure the brix content (the amount of dissolved sugars) and the acid content in a tomato. The problem with this is that the tomato must be crushed for these sensors – a shame about the tomato, but also a time-consuming and labour-intensive exercise. Comparing the results of two methods WUR is investigating whether it is possible to measure the taste of a tomato with non-destructive sensors. Two methods are being investigated - a hyper-spectral camera (that take a photo) and spectro-photometers (that take a point measurement). The results of both methods are compared with the results of destructive sensors (which measure crushed tomatoes) and those of the taste panel. This shows what the light spectrum of the tomato can tell about the taste. That knowledge can then be entered into WUR’s taste model to be able to easily measure taste in the WUR future.
Sweet peppers
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a demand for plant resources, and if the plant cannot meet the demand due to low light levels etc. high rates of abortion of newly formed fruit can occur. The influence of low light levels resulting in flower abortion is thought to result if light levels are low between the fifth and tenth day following the visual appearance of the flower bud. Unlike tomatoes, pollination of the pepper flowers occurs successfully without any outside pollination assistance required (assuming that the correct temperature targets are established). However, additional pollination assistance, bumble bees or “artificial” pollination has been demonstrated to improve flower set and eventual yield and quality of the pepper fruit.
Irrigation Target 5% over-drain early in the cycle and increase over-drain up 30% in summer. Increase the amount of water
in accordance with the demands of fruit set to harvest, taking longer the plant. If the plants have a light during the low light periods of the year. green ‘halo’ at the growing point in the The fruit is harvested at 85 - 90% colour morning, they received adequate water and a knife is used to make clean cuts during the previous day. The root zone on the peduncle (fruit stem) and care E.C. will rise if the volume of water is must be taken not to cut into adjacent not adequate. Feed at an E.C. in the fruit or stems. range of 2.5 to 3.0 mmhos to Fruit are graded Unlike tomatoes, maintain a root zone E.C. of according to size, pollination of the 3.5 to 4.0 mmhos. and the larger sized pepper usually pepper flowers occurs As the season progresses, and successfully without command a higher light levels improve, increase the number of watering events any outside pollination price. The size potential of pepper during the day to keep pace assistance required. fruit is determined with the increasing day lengths. by the cultivar, but Night watering may be considered during the management of the crop determines the summer. Target the first watering whether or not the maximum size within 0.5 hour of sunrise and the last potential is met for the greatest number of watering about 1 - 1.5 hour of sunset. fruit picked. Fruit size, as with total crop Target the first over-drain at about 10:00 yield, is a function of the management of a.m. Pepper plants can take up to 3.5 to the greenhouse environment and plant 4.0 litres of water a day during summer. handling to establish and maintain the Harvesting and grading optimal plant balance. It takes between 7 and 9 weeks from By: Dr. James Calpas.
Undercover farming I May/June 2020 I Volume 17 No 3 13
greenhouses I shade net I hydroponics I aquaponics Left: Thrips was described by Bouché in 1833 from specimens taken from a greenhouse in Europe. Packard described this species for the first time from the United States in 1870 and renamed it the greenhouse thrips, Heliothrips haemorrhoidalis (Bouché).
Thrips control in the greenhouse – Be Assertive Tiny but mighty, these pests scare growers all over the world. More than 6,000 species of thrips roam the planet, yet only five are of real concern for growers, attacking an array of crops from fruits and vegetables to ornamentals.
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he damage to these crops is a result of thrips feeding on developing plant parts, causing deformed or scarred leaves and flowers – and worst of all, transmitting various tospoviruses such as impatiens necrotic spot virus (INSV) and tomato spotted wilt virus (TSWV). One of the most reviled species of all is the western flower thrips (Frankliniella occidentalis), which quickly multiplies and ravages a wide range of host plants, but especially ornamentals. At a mere 1 to 1.5 millimetres long in adulthood, these tiny terrors inflict damage through feeding. “They have a super-special mouth part that’s like a big needle that injects into a plant cell, sucking out all the fluids from it, causing the cell to collapse. Then they withdraw and move to the next cell, scraping the tissue as they feed away. They don’t discriminate. They’ll feed on basically any soft plant tissue, other than roots. Once a thrips punctures and feeds on the plant cell, not only does it cause a visible mark on the plant, but it also kills the cell. This is especially problematic when the pests feed on developing plant parts because it curbs growth. If a feeding thrips is carrying around a tospovirus, the virus will be transmitted to the plant – a final death blow to a plant.
Physical looks Growers can spot larvae – nearly transparent white or yellowish to orange -yellow, with a large head and bright red eyes and adults, which range from white to yellowish orange to almost black. Thrips have a pointy tail end that emits tiny black specs of faecal matter and then tan, silvery, necrotic areas on the
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leaf can be really spotted if the feeding is heavy enough. What makes thrips a real threat is that the pest is hard to control. Egg to adult can happen in as little as 10 days, and adults can live for 30 to 45 days, depending on temperatures. Each thrips has four or five generations that have their own four to five generations that have their own four to five generations, and so on. Because these reproducing adults live for so long and their lifecycles are so quick, it is difficult to control them once a population is established, where every life stage is present.
Integrated approach Greenhouse attendants are to scout daily for anything and everything that comes into the greenhouse. Growers have to inspect all incoming material closely. Even if it appears clean, an egg may have been ovo-deposited inside any of the soft green tissue from the original grower. Producers must train staff to be alert to possible contamination of thrips and all other pests. Therefore training on the different pests and its growth stages, as well as where to look for these, are essential to good greenhouse management. A poster in the canteen or other gathering spot with pictures of the different insect and plant pests is a good way of constant reminding workers. Always monitor all crops at all stages and have yellow or blue (colours that attract thrips) sticky traps placed strategically above the plant’s canopy. Growers can also use the “tap” method by gently tapping the plant, while holding a white piece of paper below. If present, the pests will fall off the plant and onto the paper, where you can easily see and
count them. Blowing on flowers can also uncover hidden thrips, as they roam in the flower, adults especially. Therefore blow inside the flower as the carbon dioxide agitates them, and they move around.
Prevention Prevention is better than cure! Isolate and inspect all incoming plant material. Consider implementing dip applications of beneficial nematodes, Steinernema feltiae, oil and/or a fungal contact insecticide miticide, Beauveria bassiana, for unrooted cuttings, plugs and liners. Confine infected plants to one contained area. Never move infested plants to other growing areas because the thrips can easily spread to neighbouring clean plants. When you move plants around, the infestation is spread further. Thrips can be carried by wind and on employees’ clothing -if possible, be sure that the staff works in clean areas first, ending up in the not-so-clean areas at the end of the day. Using properly positioned fans that blow air outwards at facility entrances can also help to knock any stow-away pests off entering workers. Since thrips travel so readily, growers should screen vents and greenhouse doors, and shouldn’t leave greenhouse doors open. Weed control is most important and workers have to regularly sweep up dirt around the growing area as thrips drop to the floor and into the soil to pupate. 18
A leaf that was attacked by Thrips.
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Undercover farming I March/April 2020 I Volume 17 No 2 15
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Keeping the balance in
cucumber production The ratio of leaf canopy to root mass is crucial in achieving yield, plant vigour and plant health.
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ucumber roots have a high oxygen requirement and sudden temporary wilt; epinasty of greenhouse cucumber plants is often noted. A high solution temperature also reduces the amount of dissolved oxygen in the solution. Oxygen diffuses through air 10 000 times the rate at which it diffuses through water, thus waterlogged soils and media are undesirable. Oxygen content of a fully aerated solution at 10˚C is 13 ppm and at 30˚C it is 7ppm. This may not seem significant but at higher temperatures the oxygen requirement increases as respiration increases. Alcohol, hydrogen sulphide and ethylene are produced in the roots in waterlogged soils and media and hormone production is also disturbed. Media such as sawdust often compact over time, which leads to water logging and results in low oxygen levels in the root zone and impaired potassium, phosphate, manganese and iron uptake. The ability of water to move into the roots is reduced almost threefold in the absence of oxygen in the root zone, mainly under waterlogged conditions. The combined effects of these changes are seen as stunted or wilted tops and root death; roots will often be at the surface of the media where oxygen is available. In such circumstances, the balance of leaf canopy to roots is
compromised. In addition, Pythium is an opportunistic fungus and often takes hold of plants stressed by a combination of high temperatures and low oxygen levels in the root zone. Bearing the above in mind, basics such as media amelioration should be considered mandatory to further improve media properties and boost oxygen levels. Oxygen is part of the respiration process whereby carbohydrates are broken down to provide energy for the plant, this being the opposite process of photosynthesis. Products of respiration are carbon dioxide as well as a wide range of carbon compounds exuded from the roots. Growers often avoid removing the lower fruit on cucumber plants in a bid to get quick yields, this load on the plant at such early developmental stages draws energy from the plant that would normally be used for root development, thus reducing the root mass. Similarly, loss of leaves in the lower extremities of the plant are often evident, due to low light or infection, yet growers allow fruit to develop on these nodes where
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FloWERS
CaNNaBIS
SWEET PEPPERS
CUCUmBERS
Gerbera Producer manages during Covid-19 Page 4
Cannabis produced in cocopeat-perlite media Page 8
Sweet Peppers - Fine-tuning the growing process Page 9
Cucumbers - fertilizing tips for optimal success Page 17
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Oxygen is part of the respiration process whereby carbohydrates are broken down to provide energy for the plant, this being the opposite process of photosynthesis.
leaf abscission is noted. These fruit have no “neighbouring” leaves to supply the energy for the development of these fruit, and thus draw energy from the plant that would usually be used by the root system, thus causing a decline in the efficacy of the root system. Conversely, a poor canopy as result of poor nutrition, disease or climatic conditions will have a reduced capacity to produce energy required for fruit development and in turn having reduced energy for root development and root exudates, further exacerbating the problem and diminishing the yield potential. In such cases growers should be able to “read” the plant and remove fruit to allow the plant to carry a suitable fruit load without compromising the root system or By: M. Haupt plant health.
ADDRESS: CODE: CONTACT NUMBER: Account Name: Nufarmer Pty Ltd t/a Undercover Farming Bank: First National Bank, Kolonnade Branch Code: 25 10 37 Account No: 62007699806
greenhouses I shade net I hydroponics I aquaponics
General fertilizing principles for cucumbers
Pre-plant treatments Amending soil pH ucumbers prefer light textured soils that are well drained, high in organic matter and have a pH of 6 - 6.8. Adapted to a wide-range of soils, but will produce early in sandy soils. Cucumbers are fairly tolerant to acid soils (down to pH 5.5). Greenhouse cucumbers generally grow quite well in a wide range of soil pH (5.5-7.5), but a pH of 6.0-6.5 for mineral soils and a pH of 5.0-5.5 for organic soils are generally accepted as optimum. When the pH is too low, add ground calcific limestone, or an equal amount of dolomitic limestone when the magnesium level in the soil is low, to raise it to a desirable level. Use the rates given in Table 1 herewith as a guide; the actual lime requirement is best assessed by an appropriate laboratory test.
In order to obtain the best results when growing cucumbers for a market or export, the grass root systems for successful production must be in place.
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18 Cucumber plants trellised and ready to start production.
acidity with limestone. Peat also helps to maintain a good soil structure, but it must be added yearly to make up for loss through decomposition.
Table 1: Lime requirements for correcting soil pH to 6.5 Soil pH Sandy Loam, Clay loam, loam salty loam organic Lime mass (t/ha) 6.0 3.0 4.5 6.0 5.5 6.0 9.0 12.0 5.0 9.0 12.0 18.0 4.5 12.0 15.0 24.0 4.0 15.0 18.0 30.0 Note: The rates of lime suggested are for the top 15 cm of soil. If acidity has to be corrected to a greater soil depth, increase the rates accordingly.
Usually the pH in most greenhouse mineral soils is above the optimum pH range (6.0-6.5). A simple, though temporary solution to a high pH problem, is to add peat without neutralizing its
Healthy young cucumbers grown in grow media bags.
Stage
Pre-plant fertilizers for soil beds Apply pre-plant fertilizers after soil steaming and leaching, and incorporate them into the greenhouse soil. Add these fertilizers to the limestone that may be needed for adjusting the pH level of the soil (see Table1). Add as much of the required calcium and phosphorus as possible as a base dressing, because these nutrients store effectively in the soil and their absence from liquid feeds prevents most clogging problems of the irrigation system. Provide the calcium in the form of limestone and the phosphorus in the form of superphosphate, both finely ground. Furthermore, these nutrients, by nature of their source and their ability to bind to soil particles, are released slowly into the soil solution and therefore do not raise the total amount of salts dramatically, nor do they upset the nutrient balance of the soils to which they are added as a base dressing. Also, supply a good portion of potassium along with magnesium, as base fertilizer; the ratio of potassium to magnesium in the soil should be 2:1 and avoid applying nitrogen. Make the final decision on base fertilization after receiving the soil test results and consulting with your horticultural crop adviser. Treat the recommended rates of base fertilizers (Table 2) as a general guide only. Table 2: Recommendations for base fertilizer Fertilizer kg/ha Superphosphate (0-20-0, fine grade) 250 Potassium sulphate 500 Magnesium sulphate 250 Calcific limestone 800
During crop growth The most important element needed is nitrogen which should be supplied in the irrigation water (fertigation) at each irrigation, from soluble fertilizer materials, such as potassium nitrate (13-0-46), e.g. Multi-K™; calcium nitrate (15.5-0-0+26.5 CaO); or ammonium nitrate (33-0-0).During the first few weeks after transplanting, fertigate with 6 -11 kg/ha of N per week whilst in fruit production. 18
Grow period 4-5 months Expected yield 130-150 t/ha PPM N P K Ca Mg Transplant - Establishment 80-90 34-40 65-75 40-50 20 Fruitset 140-165 36-40 210-220 60-70 20-30 Harvest 170-195 40-44 230-250 80-90 20-30
Undercover farming I May/June 2020 I Volume 17 No 3 17
General Fertilizing Principles
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Growing in plant media In soilless systems, plants are grown with a complete nutrient solution, composed of potassium nitrate (13-0-46), or with a complete N-P-K controlled-release fertilizer (CRF), at rates of 0.6-1.2 kg/ m3 of nitrogen, or with a combination of the soluble- and the CRF materials. When used in combination, rates for each material should be reduced by 30-40%. The nutrient solution should be applied during every irrigation by fertigation at root level. Frequency of application will depend upon plant size and greenhouse temperature, but will vary from once or twice daily, immediately after transplanting, to several times per day on warm days during harvest. Always apply some pre-plant N-P-K to assure good development of the seedlings and first vegetative stage of the plants. Adjust rates to soil type, and soil test results. Kg / ha Nitrogen 50-70 Phosphorus (P2O5) 10-120 Potassium (K2O) 10-170 If drip irrigation is used, apply the 60 kg/ha (55 lbs/acre) N pre-plant.
Growing Season During growth season apply 0.6-1.1 kg/ ha N daily, or 3.5-7 kg/ha N on a weekly basis, through the dripper system. If plastic mulching is practiced, the N rate can be reduced because N losses from leaching are greatly reduced. For this culture system, it is recommended to apply 60 kg/ha N broadcast pre-plant over the row, just prior to laying the plastic. At vining, when the plant roots have reached the edge of the plastic, side-dress 35 kg/ha N on either side of the plastic. Soil pH: Optimum soil pH range is 5.8-7.0. If the soil pH is below 5.8 and the available soil calcium is less than 2,200 kg/ha, apply 2,200 kg/ha of agricultural lime 8 to 12 weeks before planting. Lime and dolomitic limestone: If soil test indicates less than 70 ppm magnesium, pre-plant application of Magnesite or Dolomite is recommended, or apply magnesium sulphate (9.8% Mg), or its equivalent at 170-220 kg/ha, by pre-plant Thrips Control in the Greenhouse
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Bio-control As far as possible, in the interest of the environment and to keep to certain enforced regulations, all possible products which are certified to fight off thrips
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broadcasting and incorporating. Lime and phosphates: If both lime and phosphates are required, both should be incorporated together 8 - 12 weeks before planting. Phosphate: On soils very low in available phosphate, apply 1,700 kg/ha of triple super-phosphate (0-47-0) or its equivalent. If the grower chooses to apply the phosphorus just before planting, monoammonium phosphate fertilizer grade (11-52-0) at 1,700 kg/ha should be incorporated in the planting row 25-30 cm deep. Organic manures are useful even for outdoor crops, especially in low CEC soils.
of these nutrients. Take care; If fertilizers are first mixed in concentrated stock solutions before they are applied to the crop, group them as indicated by the colours grouping. Do not mix the same concentrated solution of a fertilizer containing calcium and one containing sulphate or phosphate, because such a mixture forms a thick suspension that can plug watering equipment. Note: Choose soluble fertilizer formulations that are as free as possible of chlorides, sulphates, and carbonates.
Side dressing treatments The N application should be split into as many applications as possible. If fertigation (Nutrigation™) equipment is available N should be applied in every irrigation pulse. Otherwise, fortnightly dressings should be done along the harvesting period. Side-dressing N: It is recommended to apply 50 kg/ha N in a band to either side of the row when plants are rapidly vining. At least half of the nitrogen should be in the nitrate (NO3) form. For fresh market cucumbers, an additional 35 kg/ha N is usually added when the plants have 2-4 leaves and vines are just starting to fall over into the rows, but no more than 45 kg/ha of N or K2O should be applied at any one time. Pickling cucumbers are not responding to any additional N applications due to their short harvest period. Additional application(s) should be made every two weeks with the onset of harvest as side dress and covered with surface soil. The following options are recommended: • A 3:1 mixture of ammonium sulfate (21-0-0): Multi-K™(13-0-46), at the rate of 220 kg/ha • A 1:1 mixture of urea (46-0-0): Multi-K™(13-0-46), at the rate of 220 kg/h • An N-P-K complex water soluble fertilizers, such as Poly-Feed™ of the equivalent N:K ratios may be fertigated = Nutrigated™ (injected through the irrigation system). Deficiencies of Mg and of B, Fe and Mn, may occur and demand direct application
Remember these facts • Trace elements must also be added to all the above fertilizer feeds; a typical trace element mix contains 7.1% Fe, 3.48% Mn, 1.02% Zn, 0.76% Cu, all as EDTA chelates. When added to the stock solution at the rate of 1 kg/1000 L 0.485% Mo as ammonium molybdate contributes to the final solution 0.7 ppm Fe, 0.2 ppm Mn, 0.04 ppm Zn, 0.01 ppm Cu, 0.13 ppm B, & 0.006 ppm Mo, with a 1:100 dilution ratio. • Dissolve the given amount of each fertilizer, including trace elements, in 1000 L of water and add to the irrigation water in equal doses, ideally with a multi head fertilizer injector. Start injection at a very low rate and increase the rate of injection progressively and uniformly on all heads, until the desired EC is achieved. Adjust the pH of the fertigation solution to 5.5 by injecting a dilute solution of phosphoric, nitric, or sulphuric acid. Alternatively, dissolve the prescribed fertilizers, including the micronutrient mix, into 100 000 L of water, adjust the pH, and apply directly to the crop. • The recommended strength of the stock solutions is within the working range of a fertilizer injector with a 1:100 mixing ratio. If a fertilizer injector with a 1:200 mixing ratio is used, double the amount of each fertilizer. Make similar adjustments for fertilizer injectors with other mixing ratios. If the solubility limit of a fertilizer (e.g., potassium nitrate) is exceeded, prepare more than one stock solution of the same fertilizer and divide the amount of the fertilizer equally between the stocks. Source: G Burger, Haifa.
should be used. There is known resistance to certain chemicals, so the grower has to make sure he rotates the mode of action and use insecticides in a targeted, accurate approach at the right time, when it’s really required. The idea is to implement
biological strategies early on, keeping pest populations low for as long as possible. Then, when the time comes to bring out the big guns, chemistries like chlorfenapyr and spinosad will work well. By J Davidson
greenhouses I shade net I hydroponics I aquaponics
Youth harness the power of
climate-smart agriculture with aquaponics
South African youth are getting more involved in agriculture compared to a decade ago. They are increasingly learning how to grow their own crops and how to manage their livestock to ensure that there is sufficient food production.
Part of the INMED greenhouse aquaponics system.
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or South African youth, agriculture is life, particularly having experienced the challenges COVID-19 has highlighted in our more vulnerable communities,” says Menzi Khumalo, an intern at INMED South Africa who works in the Free State with a number of different farming cooperatives to implement aquaponics. Khumalo, age 27, has completed courses in fish care and breeding, and he helps with the technical aspects of the aquaponics systems at various sites in the Free State where INMED South Africa has partnered with USAID to help farmers with disabilities increase their capacity and achieve sustainable livelihoods. Born in Vosloorus, Khumalo moved to Bethlehem as a young boy. He grew up in the Free State area, attending the Bethlehem College. “Working with the farmers through the Bethlehem Farmers Trust as well as many of the youth in the area has been a blessing,” says Khumalo. “It has enabled me to form good friendships with many of my colleagues, and we have seen the benefit of aquaponics when compared to traditional farming methods.” INMED Aquaponics® is a resilient, innovative and highly intensive food production technique that combines aquaculture (fish farming) and hydroponics (soilless crop growing) in a closed system that is easily scalable to meet the needs of smallholder farmers, schools, government institutions, commercial enterprises and even home gardeners. Combined with business
Menzi Khumalo, an intern at INMED South Africa who works in the Free State with a number of different young farming cooperatives.
training, access to financing and links to markets, INMED Aquaponics® is addressing the global challenges of food security, poverty and climate-change adaptation. In a country where food security is so critical, it enables the farmers to produce throughout the year. There is 90% less water consumption, less labour and energy savings. It also is an organic process, using fish waste instead of fertilizer to produce higher-quality
Menzi Khumalo and INMED students at an aquaponics system.
produce at a faster rate than traditional farming. “It is encouraging to see how many youth in the area have embraced this new style of farming, as they will be the food producers of the future,” notes Khumalo. The communities surrounding the co-ops have been critical to the success of INMED’s work. Through a broad range of agriculture, health, social, education, family support and community development programs, it has created opportunities that build hope, selfreliance and community collaboration to sustain positive change. At a time when unemployment is also high, INMED Aquaponics® helps youth develop marketable skills to strengthen food security, income generation and climate-change adaptation. Khumalo says pursuing a career in agriculture or food production is very important to the county’s future. “Food will always be an essential need, so there will always be a demand for it. Learning how to produce and sell your own food can be cheaper and bring in more money for young people and communities,” says Khumalo. “I am excited to see interest and involvement in agriculture growing each and every year, and in the next 10 years I believe it will be a significant contributor to the economy of our country. For young people who get involved in agriculture, there is an opportunity to one day run their own farm or enterprise. Not only will this ensure sustainable employment and self-reliance but also provide much needed jobs.”
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May/June 2020
I Volume 17 No 3 19
7-8 October 2020
Remember this date!
UCF Western Cape Conference Contact Suzanne Oosthuizen 082 832 1604 Suzanne@axxess.co.za