Undercover Farming Magazine May / June 2022

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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 Yolandé van Zyl FINANCE / NEW PROJECTS Marion Oosthuizen 071 639 9300 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

Life is sweet – the sweet Palermo story

6

Know about vertical farming production

8

Donatello*, grower’s mini-plum tomato of choice

11

Prepare your greenhouse for winter

12

About Heat Storage for Greenhouses: The how

FRONT PAGE: Life is sweet – the sweet Palermo story. Read pp4

INSIDE ...

and why

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SA’s Cannabis Industry has ‘High Hopes’

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Proper irrigation methods in media culture

15

Pathogens infecting Cannabis plants identified

16

Latest Technology with great Advantages: A

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picture taken with a smartphone of plants offer

SUBSCRIBE

nutrient analysis in real-time

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Hydroponics media: Give slab production a second look

ONLINE SUBSCRIPTION Subscribe online now! E-mail your deposit and address details to: magazine@axxess.co.za More information from Suzannne Oosthuizen: 082 832 1604 See subscription form on page 16 VISIT US AT • BESOEK ONS BY

SCRIPTURES FOR WINTER

Isaiah 55:10 “For as the rain and the snow come down from heaven, And do not return there without watering the earth And making it bear and sprout, And furnishing seed to the sower and bread to the eater;

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rrrrr! South Africans are shivering during an extra cold winter. For our greenhouse producers, shade net and Aquaponics producers, cold weather means higher expenses on heating their production systems to maintain production. This in itself brings us to what is commonly written in papers, discussed on TV and in many business and private circles; the question of continued load-shedding and of late the longer periods of it. Dubious questions are asked about the origin of it all and various top-down answers are given, but not in the press, neither by government. This in itself should have the least knowledgeable ponder about the future of the country’s infrastructure. Fortunately, we are in farming and the old Afrikaans adage of ’n boer maak ‘n plan’ (a farmer makes a plan) has even become known in foreign countries! This is the time for putting heads together and come up with reasonable solutions for the greenhouse industry at large in South Africa. Quality seed is available, seedling growers deliver their best, greenhouse and systems technicians are all at hand to ensure you are in good hands. In this edition we once more focus on a few key elements in greenhouse keeping in winter, new varieties of produce and a positive outlook on growing cannabis in SA. Happy reading by the fireside; and those less fortunate that rely on Eskom power; wrap yourself in blankets like I do; just keep warm and healthy!

So shall my Word be that go forth from my mouth; it shall not return to Me empty, but it shall accomplish that which I please.” (KJV)

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GREENHOUSES I SHADE NET I HYDROPONICS I AQUAPONICS

LIFE IS SWEET –

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THE SWEET PALERMO STORY

weet Palermo – the brand name by which the unique line of dulce italiano pointed sweet peppers from vegetable breeding company Rijk Zwaan is recognised worldwide. Unique in looks and taste, the fruit from these plants are SURPRISINGLY SWEET. Bursting with wholesome aroma that elevates any dish in which it features. But don’t take our word for it. At

Rijk Zwaan we believe that the key to sharing a healthy future is to include all roleplayers in the fresh produce value chain. And in doing so we stay up to date with worldwide consumer trends and market requirements. Including consumer research projects and competitions where we let consumers do the talking. The verdict – seven consumer awards in 10 years since 2012. Of which most recently the 2022 Taste of the Year award from Spanish consumers. Sweet Palermo addresses the desires of consumers, providing a healthy yet tasty alternative. Tastier than a normal blocky pepper with a brix value of 6-7 brix. Sweet Palermo boasts a brix value of 8-9.5 brix. The fruit also has minimal seeds which makes preparation a breeze. The Sweet Palermo fruit are exclusively grown by selected growers that form part of the Sweet Palermo Growers Group. Grower partners receive exclusive access to new Rijk Zwaan varieties that conform to the high standards set for this premium brand.

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The brand originally started out with only the red Sweet Palermo, but has now expanded to include yellow and orange colours. With the most recent addition being the chocolate coloured Sweet Palermo. Varieties are rigorously tested before forming part of the brand and also include the necessary resistances, plant physiological and yield traits that makes it successful as a commercial crop for the grower. For more information on the Sweet Palermo variety, visit www.rijkzwaan.co.za


GREENHOUSES I SHADE NET I HYDROPONICS I AQUAPONICS

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Rijk Zwaan offers a wide range of high-quality vegetable varieties. We select and test them thoroughly to ensure their suitability for growing in South African conditions. In addition to the seeds themselves, we also provide reliable information about the performance of our varieties and expert cultivation advice from our crop specialists. This ensures the grower has the best start to a successful harvest.

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36 Steyn Road, Rietvallei Farm Krugersdorp 1739 South Africa | Postal address P.O. Box 2259, Ruimsig Krugersdorp 1732 South Africa Tel: +27 61 120 3082 / 116 9690 / 116 956 Undercover farming I May/June 2021 I Volume 18 No 3 5 Email: info@rijkzwaan.co.za | www.rijkzwaan.co.za


GREENHOUSES I SHADE NET I HYDROPONICS I AQUAPONICS

KNOW ABOUT VERTICAL FARMING PRODUCTION

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urrently, the global human population exceeds more than 7.85 billion, but this number is expected to increase to 9.8 billion by 2050— with more than 75% of people expected to be living in urban areas. Accompanied with this population growth will also be an increase in demand on already stressed food, water, and energy resources needed to sustain this growth. Thus, new agricultural systems that offer sustainable food production will be essential to meet these demands. One such system, that many believe can meet these demands, is vertical farming. But, what exactly is vertical farming and why do many people believe that? Let’s find out! What is Vertical Farming? Simply put, vertical farming is the practice of growing plants in vertically stacked layers. This method of horticulture seeks to maximize plant space utilization and production by scaling up off the ground, allowing more plants to be grown in the same area.

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Additionally, it can be applied to current horticultural practices, ranging from small-scale hydroponics to large-scale controlled environmental agriculture operations, and has the potential to produce year-round production at practically any location if coupled with the right techniques! So, how does it work, what plants are grown, and more importantly, is it sustainable? Basic Components of a Vertical Farm Vertical farm types can be broken down into three main components: the (1) system structure, (2) electrical structure, and (3) plumbing structure (see figure below). These three aspects are vital to consider as they will dictate where a system can be located, what crops can be grown in them, and the resources that will be required to build one. They should be considered before starting a vertical farming operation. Types of Vertical Farms Figure 1: Vertical farming operation utilizing hydroponic A-Frames

When it comes to vertical farming, there are three main system types: (1) hydroponics, (2) aquaponic, and (3) growing-media based systems. Hydroponics Vertical Farming In hydroponics vertical farming, an aqueous solution comprised of all essential nutrients needed for optimal plant growth is supplied to plants. Examples of this type of vertical farming includes modified hydroponics systems, such as nutrient film technique (Ex. A-Frame and vertical grow towers), deep water culture (DWC), and aeroponics. Aquaponic Vertical Farming Conversely, in aquaponic vertical farming, fish production is integrated with plant production utilizing hydroponic system designs. However, instead of fertilizing plants with an aqueous solution comprised of all essential nutrients, plants are alternatively fertilized with nutrientrich fish water that has been filtered, converted to nitrates, and supplemented for limiting nutrients deficient in aquaponic systems.


GREENHOUSES I SHADE NET I HYDROPONICS I AQUAPONICS

Growing Media Selection for Vertical Farming The best media to select for a vertical farming system is one that promotes good air porosity, drainage, and nutrient retention. This is necessary to assure that plants do not stay drenched for prolonged periods of time, while also providing a good structure for newly developing root systems to grow in. Several exceptional growing media products are available, designed to establish the proper foundation essential for vertical growing. A producer requires a well-balanced, general purpose growing medium that has a blend of medium textured Sphagnum peat moss, perlite, vermiculite and a starter nutrient charge suited for large cell cultivation. For organic growers a medium textured growing medium is required. Furthermore, each of these products are available with active ingredients, Advantages and Disadvantages of Vertical Farming Finally, when it comes to growing vertical farming, this method offers a variety of benefits over other plant production practices. Such benefits associated with vertical farming include higher rates of production, improved crop quality, lower water usage, reduced fertilizer usage, reduced area required for production, and the

potential for yearround production at just about any location. These systems can be quite profitable and have the potential to be part of environmental solutions if properly designed and managed. Nonetheless, it is important to note that there are drawbacks associated with vertical farming. First, these systems can be seen as “high risk”. For example, they are very energy intensive and require that backup systems be in place in case of power outages. Second, they require a high level of technical “know how” to operate and can be costly to set

up, monitor, and maintain. Lastly, these systems can be more susceptible to water-borne diseases or pests, which once in the system, can quickly spread from plant to plant due to the interconnectedness of these systems. For these reasons caution and planning is advised. In cases where growing media is used, the addition of biological additive ingredients can be beneficial to reduce the onset of plant root diseases and reduce plant loss. By: Nathan Wallace-Springer

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GREENHOUSES I SHADE NET I HYDROPONICS I AQUAPONICS

Donatello*, grower’s mini-plum tomato of choice

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rett Miller recently acquired a farm in the coastal belt just north of Port Alfred a few miles off the R72. A farrier by trade and after many successful years working in his profession, he and his wife Sally decided to start farming. With a passion to turn the soil, they started from scratch with only a couple of greenhouses. Initially, Brett began growing various well-known and market-leading varieties to support his new lifestyle. It was only after a couple of crops that he then contacted Nuvance for advice and variety options. I realised on my first visit that Brett was not going to be easily swayed, but he remained open to different views and suggestions. He was also very willing to look and trial new varieties/ options as the local demand for his mini-plum tomatoes grew. Nuvance, with its recent acquisition by Dutch-based Bejo, is now in a leading position to supply varieties of numerous crop categories that can compete equally and often better than some of our competitor varieties. The timing was thus perfect. With the help of our product development manager, Dr Quintin Muhl, we sourced several new varieties and amongst them a phenomenal mini-plum tomato variety which we knew would suit our producer’s specifications here in Southern Africa. One of these varieties was the new NTOM005, which Brett agreed to put to the test. The trial was very successful and for his subsequent planting, Brett decided to order a large portion of NTOM005 to supplement his growing orders for mini-plum tomatoes.

Freshly packed Donatello*.

NTOM005 has been a great success countrywide and was recently submitted for registration as Donatello*. A perfectly sculpted mini-plum tomato that is guaranteed to yield. Donatello* has a very

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GREENHOUSES I SHADE NET I HYDROPONICS I AQUAPONICS

advancing beyond the basics seeds | science | service

Donatello* Earliness

Very early

Maturity

55 – 60 days

Plant

Indeterminate

Fruit

Cherry Plum (brix ±9.0)

Average fruit weight

22 – 24 g

Disease resistance/tolerance

ToMV, TYLCV, TSWV, F1, N

Features/benefits

Excellent fruit quality combined with high yield potential. Strong plant growth habit with very early maturity for all major and various climate conditions. Donatello* is suited for single fruit or cluster picking. Double stem pruning is recommended to increase the number of fruits per plant. The fruit are firm and offer extended shelf life.

For full terms and conditions, please visit www.nuvance.co.za / * pending variety listing.

| www.nuvance.co.za |

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GREENHOUSES I SHADE NET I HYDROPONICS I AQUAPONICS

8 DONATELLO*

Brett Miller and Dr Quintin Muhl (Nuvance)

good disease package including Tomato Mosaic Virus (ToMV), Tomato Yellow Leaf Curl Virus (TYLCV), Tomato Spotted Wilt Virus (TSWV), Fusarium (Fol:1) and Nematodes (Ma/Mi/Mj). Key benefits observed by Brett between Donatello* and another marketleading variety were that Donatello* plants were more vigorous, earlier into production and ultimately had the higher yield. Also, Donatello* showed good field tolerance against powdery mildew, whereas Brett had to react with immediate and regular spraying on some of his other varieties to bring the powdery mildew under control. An issue that many growers are familiar with especially along the coastal routes where the relative humidity is often high. As a developing producer, Brett also grows cucumbers, peppers and regular round tomatoes all under plastic. This diversity of vegetable crops assists him to maintain a progressive cash flow without being dictated by the market of a single crop. Brett also packs all his produce on the farm under the label of ‘Chelsea Veg’

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which also allows him some leverage when it comes to the surrounding markets. Sally is equally invested in the business by keeping the finances in order and the customers content. Often when I’m quizzing Brett on issues of the business regarding costs, he replies with ‘just ask Sally’ with a gentle smile.

Recently their son Liam also joined the operation and the expansion of their farm continues. We at Nuvance continue to work closely with Brett and Sally and are confident that they will grow the business according to their long-term vision. We look forward to being a small contributor to their success.


GREENHOUSES I SHADE NET I HYDROPONICS I AQUAPONICS

Prepare your greenhouse for winter

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ith the arrival of winter and the cold weather, you need to be well prepared. Using extra artificial lighting and heating, choosing the right crops, as well as cleaning and inspecting your greenhouse are important steps to consider. Cleaning your greenhouse Start by removing seasonal plants, old crop substrates, hooks and ropes; then sweep the floors and discard all containers that are broken. Clean the floors with soap and water and rinse thoroughly and also clean the roof cover with a mild detergent. Wash the entire structure and all accessories in your greenhouse. Take an inventory of your tools and reorganize them as needed.

time and throughout the day. The tools recommended for winter cultivation include single or double thermal screens, double polyethylene plastics and a plant heating system, as well as artificial lighting for extra heat. A high-tech greenhouse equipped with these tools will optimize your winter greenhouse production. Ventilating your greenhouse in winter Ventilation is essential during the winter season. The vast difference between

the temperature inside and outside makes managing moisture difficult and promotes the spread of diseases. Make sure you choose the right time to start ventilating your greenhouse to prevent the development of conditions that make the crops weak and susceptible to disease. Properly preparing your greenhouse for winter is essential. Discover different types of equipment that will allow you to have a successful winter production. Information: Harnois

Inspecting your greenhouse • Make sure the roof cover is not cracked; • Examine the existing insulation; • Add additional insulation to the north facing wall; • Inspect the heating system; • Inspect the ventilation system. Choosing the right crops for winter production You will need to choose the right crops for this production period. In winter, greenhouse vegetables need heat, which you will need to provide at the right

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GREENHOUSES I SHADE NET I HYDROPONICS I AQUAPONICS

About Heat Storage for Greenhouses: The How and Why

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torage of heat for future use is an old idea used in industry and in solar homes. It is becoming popular now that alternate energy systems are being installed for greenhouse heating. Many systems have been developed depending on the source of the heat and the storage medium. Heat can be stored for short periods of time as from day to night or for longer periods such as from summer to winter. Trees store energy for a century or more. Coal and oil store the sun’s energy for thousands of years. Several heat storage concepts can be used in greenhouses. Let’s look at a few of them. Daytime storage of heat for night time use Carbon dioxide can increase plant growth. One of the by-products of the combustion of fossil fuels is CO2. Capturing this from the flue gases and distributing it in the greenhouse costs very little. As CO2 is effective only during the day and heat is not normally needed at this time, storage of the heat is required to make the system efficient. Large insulated water storage tanks are used to store the heat for use at night. In the greenhouse industry the system is used for water storage with alternate fuel heating systems with limited cycling. Matter such as wood and coal are most efficiently if operated at a constant fire rate. Adding a large, insulated water buffer tank can store excess heat during the daytime operation to be used at night when the heat demand is the

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greatest. This can reduce the size of the heating system needed. Tanks with capacities of 1,000 gallons to over 500,000 gallons are available. They are usually steel with an interior liner or anti-rust coating and a heavy insulation on the outside. An exterior metal jacket protects the insulation. Smaller tanks are delivered by truck. Larger tanks are assembled on site. Design of these systems allows for a smaller boiler as the water storage carries part of the night-time load. Typical design looks at the maximum heat needs for the coldest day. It also considers the maximum tank water temperature that can be achieved, the lowest water temperature that can be used and the storage period. Maximum water temperature is around 200ºF. The lowest temperature water for distribution in steel pipes or fin radiation is around 150ºF. A lower temperature

water can be used if root zone heating system is installed. Storage period may be from one to two days. Typically storage capacity is one gallon per 200 – 300 Btu/hr of boiler heat capacity. For small growers with a good wood supply and a few plastic tunnels, an outdoor wood boiler may be a good alternate fuel source that will lower heating cost. These are available with capacities up to one million Btu/hr output. Installing a 11 356 to 15 142 litres insulated water tank can provide the buffer capacity needed to store excess heat for the night. Capturing excess greenhouse heat On bright, sunny days in the autumn, winter and spring, there is usually excess heat that needs to be vented. Capturing this heat for night-time use is a possibility. The amount of usable heat is approximately 61 – 400 Btu/sq meter

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GREENHOUSES I SHADE NET I HYDROPONICS I AQUAPONICS

SA’s Cannabis Industry has ‘High Hopes’

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ollowing a commitment by President Cyril Ramaposa during the 2022 State of the Nation Address (SONA) that the production of cannabis in the country would soon be industrialised and government would be seeking to “harness” the economic benefits of this burgeoning sector – it’s no wonder the tone leading up to this year’s Cannabis Expo has been extremely positive. Furthermore, the fact that the first Cannabis Expo since the pandemic hit is taking place in Cape Town during March, with the Western Cape region beginning to emerge as one of the leading provinces in the industry after being recorded in 2021 as having the most exports for cannabis originating from here – he expressed his confidence in the attendance and interest by businesses and consumers. South Africa is a sleeping giant that has the potential to become a major player in the global cannabis market. Regulatory rules drive outcomes in cannabis, impacting everything from product diversification, to growing your consumer base, to revenue growth rates. The net result is strong growth in a global market that grew 42% to $21.7 billion in 2020 and was forecast to grow at a compound annual growth rate of 19% to $51.7 billion in 2021.

However, to tap into the exciting potential that the global market offers to the cannabis industry – the key lies in the cultivation and risks associated with cultivation of this crop and how the quality of crop grown is critical for South Africa to be a global exporter and to bring about meaningful growth for this sector. One key challenge that growers face around the world, is how to tackle the formidable powdery mildew issue. Not surprisingly, this burning issue has been spoken about timelessly with powdery mildew being the most destructive in cultivating and growing successful cannabis crops. We hear discussions all the time, on how to tackle this serious issue. Some solutions for growers include using a number of oils and sprays to help temper contamination. However, one new solution to counter powdery mildew that stems from a very unexpected place (space in fact) and is sure to turn heads at this year’s expo, is Airocide®.

Trials are already underway with more planned in the Western Cape and Gauteng region this year using this innovative air purification technology on their licensed crops with some growers already exclaiming a marked improvement and success. The intended outcome is that by using this technology in areas where crops are grown indoors that growers can significantly reduce mould and other airborne pathogens that negatively impact the cannabis crop’s growth and quality. With Cape Town being the first venue to host the Cannabis Expo this year, and others planned to happen later in the year in areas like Durban, Pretoria and Johannesburg – it will be exciting to see what other interesting innovations come to the fore at this year’s events to support the growing cannabis industry; and which province will stake and secure their claim to be the nucleus of SA’s and Africa’s cannabis industry. PR

These units were introduced into Africa only recently and use optimised photocatalytic oxidation (“PCO”) technology developed for NASA to control and kill infections. Already successfully used in the US and other areas around the world to help mitigate the problem of powdery mildew – it has sparked interest in local growers.

12 ABOUT HEAT STORAGE of floor area depending on which area in the country your greenhouse is located. For example, a 30m x 10m greenhouse could have from 600,000 to 1,200,000 Btu of excess heat. It is a low degree heat with maximum temperature of about 32.22ºC. Capturing and storing this heat is not easy. It could be collected with ducting near the ridge and stored below the floor in a rock bed. It could also be collected with a heat exchanger and the temperature increased with a heat pump. It could then be stored in an insulated hot water tank. The cost of

the equipment and operation may be prohibitive. An economic study should be done first. Research in Europe and elsewhere has been exploring the installation of heat storage below the greenhouse floor. A water tank or tank filled with wet sand is the storage medium. The soil below the floor could also be used. Collection can be either from the excess heat in the greenhouse or from solar collectors. Recovery is through water pipes or air ducts spaced throughout the storage area. This system can add considerable construction cost to the greenhouse.

When evaluating heat storage, the storage medium needs to be considered. Heat capacity is measured as specific heat. Water has a specific heat of 1.0 Btu/sq ft - ºF, whereas concrete, crushed rock and sand are approximately 0.2 Btu/sq ft - ºF. On a volume basis, water holds about three times as much heat as the concrete, rock and sand. Heat storage can provide a buffer that allows a smaller heating system to be installed. Selection of the system and its size are important to making it economic.

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GREENHOUSES I SHADE NET I HYDROPONICS I AQUAPONICS

PROPER IRRIGATION METHODS IN MEDIA CULTURE

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he lack of understanding important principles of good irrigation as one of the key facets of successful hydroponics production is one of the biggest causes of problems experienced on farms on a regular basis. The greenhouse industry, like all other industries these days, is under continuous pressure to increase production while facing continuously rising input costs, yet many growers continue to irrigate in ways that do not promote good production. The bag culture system such as that used by most tomato, sweet pepper and cucumber growers in South Africa may be out-dated, but that doesn’t mean that good yields cannot be achieved using this system, provided good irrigation practices are used in conjunction with good equipment and a good growing medium. So why can’t we just irrigate with a clock timer at predetermined intervals which are altered on a seasonal basis to achieve a targeted over drain percentage? The reality is that plants do not take up water like clockwork and can vary this uptake substantially on a day-today basis. For example, mature tomato plants can take up 2 500ml one day and

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300ml the next as the weather changes. Manual adjustments cannot adequately compensate for this, with the result that plants are often too wet or too dry, at the wrong time of the day, and production losses are inevitable. Also, it becomes very difficult to manage EC. The uptake of water is strongly correlated to light intensity and accumulated light energy and is influenced by temperature, humidity, air movement and the leaf area of the plant. Using a solarimeter to assist your irrigation controller is a reliable means of scheduling irrigation to coincide with the prevailing light conditions, by far the largest determinant of water uptake, and using a reliable water content meter or, alternatively, a scale system which actually weighs the bags continuously will complete the picture.

This does not have to be an elaborate, expensive system and can either be a scale hooked up to a computer for logging purposes or a simple one with a digital display which can be read at certain times of the day. Knowing what is going on in the bags or slabs is one of the mysteries of hydroponics, yet managing water content is one of the few things over which we can have complete control. We just need to have the right tools. Using the tools mentioned above, you can make important decisions as to when and how much irrigation is required on a day-to-day basis, as well as refining your general irrigation strategy for the steering of your plants. By: Martin von Holdt


GREENHOUSES I SHADE NET I HYDROPONICS I AQUAPONICS

PATHOGENS INFECTING CANNABIS PLANTS IDENTIFIED

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annabis has become an important part of the greenhouse industry economy. This means it’s important to make sure cannabis plants grow as well as they can. a study in Frontiers in Agronomy documenting the presence of pathogens infecting cannabis plants Ph.D. candidate Cora S. McGehee and associate professor of horticulture Rosa E. Raudales from the College of Agriculture, Health and Natural Resources was published in 2021. This was the first paper that showed these pathogens are present in Connecticut’s cannabis growing facilities. Plants of all kinds, including cannabis, suffer from infections by a variety of pathogens. So, McGehee and Raudales stumbled into this study by accident. McGehee’s research focuses on plantmicrobe interactions in relation to root diseases caused by pathogenic Pythium species in hydroponic lettuce. But her training and Raudales’ expertise in plant pathology put them in a unique position to address similar concerns in a new, high potential crop. “It’s unavoidable with all the cannabis production around us,” McGehee says. They were called in on a site visit to assess overall plant health on some cannabis plants in a Connecticut facility. However, during their visit the researchers quickly realized some of the plants were symptomatic of root rot, a disease that causes yellowing, wilting, and reduced growth. From there, the researchers’ curiosity took over as they tried to get to the bottom of this disorder infecting these plants.

The researchers took soilless substrate samples from coconut coir and rockwool the plants were growing in and performed a series of analyses and experiments. They took samples from the seedling stage as well as mature plants. First, they looked at the morphological characteristics of the organisms obtained from the soilless substrates. By looking at the size and shape of the sexual and asexual structures under a microscope, the researchers were able to identify what kind of organisms they were looking at. From there, they isolated DNA from the organisms, amplified genes specific to the organisms, and sent the amplified products to Yale University and Eurofins Genomics LLC laboratories for sequencing which allowed McGehee and Raudales to match their organisms sequences against a national database containing other researchers’ sequences to confirm their identifications. The researchers identified one isolate of Fusarium oxysporum, three isolates of Globisporangium irregulare and 21 isolates of Pythium myriotylum. Aside from being the most abundant pathogenic species in the samples, Pythium myriotylum isolates were also the most virulent, or harmful, pathogens. “Once infected, it’s very difficult to revive the plant and use it for profit,” McGehee says. “It’s pretty much a goner.” The pair then conducted pathogenicity assays with hemp in the laboratory and greenhouse. They set up hundreds of hemp plants in UConn’s Plant Science Research greenhouse and intentionally infected them with the pathogens.

After monitoring these plants carefully, checking daily for symptoms the researchers confirmed all the species and isolates they tested were pathogenic to cannabis plants. Identifying pathogens of concern provides cannabis growers with important information. By knowing which pathogens “like” cannabis plants, growers can adopt more effective prevention strategies that specifically target these pathogens. For instance, Pythium species thrive in wet environments. This means growers should be sure to avoid overwatering their crops. These pathogens also spread easily, meaning growers need to remove infected plants and debris as soon as possible to prevent the pathogen from infecting other crops in production. The study also found the pathogens were sensitive to mefenoxam, the active ingredient in chemical fungicides used to suppress Pythium. However, this chemical is not labeled for use on cannabis crops. Growers can employ other strategies such as monitoring water use, pH, and soluble salt levels as well as cleaning, sanitizing, and using biological fungicides to mitigate the impact of these pathogens. “It’s important for growers to start matching these diseases with the pathogens that cause them,” McGehee says. “I think that will help management strategies and prevent disease outbreaks in their facilities.” Source: Anna Zarra Aldrich, College of Agriculture, Health and Natural Resources, University of Connecticut

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recommendations for fertilization. GREENHOUSES I SHADE NET I HYDROPONICS I AQUAPONICS

LATEST TECHNOLOGY WITH GREAT ADVANTAGES: A picture taken with a smartphone of plants offer nutrient analysis in real-time

3 4

A revolutionary, simple and fast system by Croptune (developed by the startup company AgrIOT and empowered by the Haifa Group), integrates science and technology, and enables the identification of deficiencies of the three major nutritional elements of plants (nitrogen, phosphorus, and potassium).

cotton, rice, wheat, maize and orchard crops, including avocado, banana, pear, cherry, peach, nectarine, clementine. Additional crops like soft fruits and greenhouse vegetables will be added during 2022. By using Croptune, farmers worldwide will be able to identify nutrient deficiencies, directly in the field for the first time. Croptune’s App advantages Incorporating Croptune into your workflow will help reduce soil, water, and atmospheric pollution that contribute to the crop’s carbon footprint and will allow for better water management & reduce soil salinity. This is achieved by optimizing the amounts of added fertilizers.

D

uring this era of technological developments and a rising demand for agricultural production, precision farming has become of great interest. Croptune is a simple, easy-to-use decision support application to reduce costs for farmers while improving the classification of nutrient deficiencies and protect the environment. Croptune uses innovative technology for monitoring nutrient deficiencies in the field and provides immediate fertilization recommendations for various agricultural crops via smartphone.

oose crop

Plants the Sensor Plants are the best natural sensor for identifying deficiencies and reveal when and what they need if nutrients are missing in order for growers to act immediately and achieve maximum yield.

recommendations. A simple, one-time, setup with ongoing analysis becomes the perfect solution to answer rising operational costs.

Take pictures

Current protocols for measuring nutrient deficiencies in the field rely on sending samples to the laboratory. This procedure is time-consuming and cannot provide growers with real-time decision support. Croptune solves this problem by using a unique technology that allows real-time, on-site identification of nutrient deficiencies by using a regular smartphone.

Motti Levin, CEO of Haifa Group says "Croptune is a significant breakthrough in precision agriculture and will lead to a dramatic increase in nutrient use efficiency wherever it is applied. This product has great potential and benefits both the farmers and Haifa's official distributors.

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Nutrient use efficiency is the most complex and worrying issue the agricultural world faces, and we anticipate great demand for this stateof-art technology."

Haifa's global distribution network, based on 17 subsidiaries and their local agronomists, are dedicated to spreading the product across the globe. The Croptune app is compatible with Apple and Android systems and is available in the App Stores as well as through Haifa distributors, for a discounted price.

n operations according to the actual statu gs” or wild guesses. Croptune is a real-time, mobile application that combines image analysis, big data & cloud computing, for recognizing nutritional deficiencies. A simple picture, taken with any smart mobile device offers growers, agronomists, and agricultural consultants a unique view on crop condition and Nitrogen uptake, along with tailor-made nutritional

Smart phone images taken on-site

Croptune uses images taken with any smartphone with machine learning and big data, to calculate nutrient uptake, then provides fertilization recommendations. Croptune currently supports analysis of diverse field crops including lettuce, carrot, bell pepper, tomato, potato, cucumber, onion,

Contact your Haifa South Africa Agronomist Nico Neethling (072 038 3380) or Gerrit Burger (082 800 8766) today and get an offer that suits your needs. https://www.haifa-group.com/ croptune-precision-agriculture

onsuming lab analyses, helping you optimize 16 Undercover farming I May/June 2022 I Volume 19 No 3


GREENHOUSES I SHADE NET I HYDROPONICS I AQUAPONICS

Precision agriculture at a click Take a picture with your smartphone and get nutrient analysis of your crops - in real-time! Avoid excessive fertilization

Save money

Enjoy maximum yields

Croptune is a unique agri-technology that helps growers optimize fertilizer application - for healthy growth and maximum yields. Croptune determines the crop's nutritional status, instantly detects deficiencies using a standard smartphone camera and provides recommendations for fertilization.

1

2 Sign in

Choose crop

3 4 Take pictures

Get analysis & recommendations

No more guessing Croptune helps you set fertilization operations according to the actual status of your crops, rather than counting on “gut feelings” or wild guesses.

Your private lab in real-time Cropetune saves you costly, time-consuming lab analyses, helping you optimize your fertilization programs according to the actual status in the field.

Contact your Haifa representative today, and get an offer that suits your needs.

Developed by AgrIOT, Powered by Haifa Group

Undercover farming I May/June 2022 I Volume 19 No 3 17


GREENHOUSES I SHADE NET I HYDROPONICS I AQUAPONICS

HYDROPONICS MEDIA: GIVE SLAB PRODUCTION A SECOND LOOK

F

or growers implementing controlled environment methods for crops such as cannabis and edibles, new media options can maximize crop growth. Many proven practices in horticultural production can be leveraged to increase efficiencies in cannabis and other hydroponic production. One place to start is by examining options in growing media. While peat-based media prevail in the ornamental market, the world of controlled environment agriculture (CEA) is dominated by hydroponic production methods. Leafy greens are generally produced in obvious hydroponic systems, including floating rafts and nutrient film technique (NFT) systems. Other CEA growers combine container-based production systems with an inert or low-reactive media that provides support but little fertility. Examples of this strategy include Dutch buckets and 100 percent coir media in traditional pots. However, one production method clearly leads the market for hydroponic production: the slab method. Growers commonly use the slab method to

18 Undercover farming I May/June 2022 I Volume 19 No 3

support hydroponic production of high-wire crops, including tomato, cucumber and pepper. The slab method is also readily adaptable to cannabis production. The slab method ingeniously supports crops from propagation to harvest while avoiding any transplant-related stress. Propagation begins in a plug. As the young plant matures, the plug is placed into a dibbled or carved hole in a larger block, generally 3 to 4 inches square. The young plant is grown in the blocks at high density while it quickly roots into the surrounding media. As the roots penetrate to the edges of the block, the block is placed on the surface of a larger slab. The roots move into the slab, which will support the plant for the remainder of its production cycle. Rockwool media has dominated slab production for many years. Also called stone wool, rockwool affords several desirable attributes for production, most remarkable being its inert nature. However, rockwool presents a significant drawback: Disposal can be challenging because rockwool does not break down.

For growers for whom disposal is a problem, two other options now exist for slab production. Two media alternatives solve the disposal problem while maintaining the integrity of the slab system. Both provide all three components for the system (plug, block and slab), and both offer slabs wrapped in poly for ease of use, even moisture levels and minimizing algae growth. Therefore, while implementing a change in media types will, of course, lead to a change in irrigation strategy, the transition won’t alter the basic production approach. Space utilization and crop stages match the known process, right down to the placement of drip tubes. Coir The first alternative media to adopt the slab system was coir. Coir has grown in popularity as a peat alternative in conventional production due to its plentiful, renewable supply and positive attributes for root growth, including good water holding capacity and high porosity.


GREENHOUSES I SHADE NET I HYDROPONICS I AQUAPONICS

Coir offers about half the cationexchange capacity as peat, which means it holds less nutrition than peat. For all practical purposes, pure coir presents a hydroponic system. Coir is considered to be the most environmentally friendly of the three media types most commonly used in slab grow bags. Of the three, coir alone provides an organic option; it’s relatively easy to find an OMRI-listed coir slab. Once the poly bag is removed after production, the coir can simply be composted. Readily available, easy to grow in and easy to dispose, costeffective coir is an appealing solution for many growers. Consider a few factors when switching to coir slabs. First, look for a product with a low EC to avoid the need to leach or condition prior to planting. Next, look for consistent quality and a blend developed for your particular crop. The FibreDust product line, for example, ships with a very low EC (less than 0.5 mS/cm at shipping), and offers readily available blend options and strong product consistency. Slabs ship compressed and dry. They fluff naturally after irrigation. While FibreDust products won’t require conditioning, allow several hours for the product to fully hydrate prior to use. Phenolic Foam The newest option for slab production brings an intermediate solution to rockwool and coir. The Easy Plant

Subscribe now! Email the details as outlined here to subscribe for your bi-monthly copy of Undercover Farming! Send this information to magazine@axxess.co.za with your subscription deposit proof of payment. For more information contact Marion Oosthuizen (+27) (0) 71 693 9300 or e-mail management@axxess. co.za

Rockwool

Coir

Oasis Easy Plant

Organic

No

Yes

NO

Mechanical and biological breakdown

No

Yes

Yes

Inert

Yes

No

Yes

Sterile (at manufacture)

Yes

No

Yes

Heavy

Heavy

Light

Weight Table 1. Media comparison chart. System from Smithers-Oasis utilizes the well-known Oasis phenolic foam in slab and block forms. Like rockwool, the media is inert; it won’t interact with nutrients or crop-protection products. Unlike rockwool, Oasis’ phenolic foam will break down over time. The breakdown process takes longer than for coir, but mechanical and biological break down will occur over 18 to 24 months. This timeline for breakdown means that the product will maintain its integrity during production. Phenolic foam is a manufactured product. This means that the product is highly uniform, highly consistent and also sterile at the time of manufacturing. Both density and pore size are controlled during the manufacturing process. Some of the pores are sized to hold moisture while others are sized to hold air. Since air is always held in the foam, the crop cannot be overwatered. Lightweight foam brings additional advantages when it comes to shipping

costs: Low weight translates into low freight. Table 1 summarizes the differences between coir and Oasis slab systems: When moving from rockwool to coir or foam, growers should expect to modify their irrigation strategy. Moving to coir may also warrant a slight adjustment to the existing fertility program. Consult your supplier for guidance in making adjustments to maximize crop growth in the new media. By: Tami Van Gaal

Coir is considered to be the most environmentally friendly of the three media types most commonly used in slab grow bags.

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