Keeping plants and neighbours content with this light abatement strategy | 36
Mixing it up Breathing new life and profits into your combinations.
What plant parents want
Garden centres need to evolve with the new shopping landscape. By Anne-Marie Hardie | 30
Editorial 4
Industry News 6
New Varieties 8
Business Issues 10 Transforming the IGC experience
Technology Issues 11 Microbial balance in the root zone
New Edibles 26 from CAST 2019
Lighting Q&A 50 with Dr. Melanie Yelton
Battling Botrytis 52 A serious disease for greenhouse lettuce
Nutrient Transport 56 How malnutrition transpires
New and Notable 60 in horticultural lighting
Inside View 62 Is it time to act?
BY MELHEM SAWAYA
Counting the days
How to predict first flight of the European corn borer
BY
CARA MCCREARY AND TRACEY BAUTE
A climactic balancing act Ways to promote your crop’s selfcooling strategies, both day and night
BY PETER VAN WEEL
N. JABBOUR
M. SAWAYA
Voting with eyes wide open
I was honoured to be one of ten individuals invited to an AllAmerica Selections (AAS) trial garden luncheon a few months ago. From the Cal Sweet Bush watermelon to the Butterscotch squash, the University of Guelph’s culinary team prepared a number of tasting plates, each highlighting one or more AAS winners grown right in the university’s AAS trial gardens.* With eight other garden writers at the lunch table, the conversation inevitably turned towards changing times and how the consumption of information has changed. When was the last time you saw an encyclopedia? Information is now easily accessible online. Each search results in an unmanageable number of hits on your topic of choice. The consensus around the lunch table was that there’s incorrect gardening information online – and lots of it. But how can anyone with no prior knowledge of the subject matter distinguish between the correct and the incorrect? Can Google be trusted to deliver the most accurate hits at
from millions of Facebook profiles were taken and used for political advertising purposes without people’s consent. For the 2016 American elections, the company used the information from Facebook to surmise whether an individual had the profile of a ‘persuadable.’ Those that seemed to be on the fence were fed contrived ads disguised as posts from false Facebook groups designed to tip their vote.
...where is the accountability if something proves to be wrong?
the very top?
Adding to the confusion, much information is now delivered via social media, enewsletters, and other vehicles. Because of the sheer amount of information available and daily time constraints, it seems easier to have someone else curate the content for us. Newspapers and magazines tend to build up sizable readerships based on their content’s breadth and accuracy. But now with fleeting tweets and links to unknown blogs, where is the accountability if something proves to be wrong?
In the Cambridge Analytica scandal of early 2018, information
As the Canadian federal election draws near, similar concerns are in the public eye. At the time of writing, CBC News revealed that a number of websites for individual members of parliament have trackers that can be used to deliver targeted advertising, which can then trigger re-election ads on social media or other websites. “The governing policy for MP websites does not cover the use of trackers,” Heather Bradley, spokesperson for the House of Commons tells CBC News. “MP websites linked from the House of Commons members’ information page cannot be used for campaign purposes.”
Before you cast your ballot this year, talk to those you trust. Whether it’s your local greenhouse association, your provincial extension personnel or your local greenhouse study group, take in all the information and different points of view before you make a decision. (Last I checked, not every party seemed to have a clear plan for replacing the federal carbon backstop.) Go vote!
*Thank you to Connie Dam-Byl of William Dam Seeds and Rodger Tschanz of the University of Guelph for hosting this event.
to the publisher’s approval. Such approval does not imply any endorsement of the products or services advertised. Publisher reserves the right to refuse advertising that does not meet the standards of the publication.
Ontario agri-food excellence awards open
Applications for Ontario’s 2019 Excellence in Agriculture program are due October 11, 2019. The program recognizes agri-food innovations and advancements that demonstrate leadership, product development or technology advancement that will benefit the sector. In addition to primary producers, processors and agri-food organizations, the program has introduced a new category to recognize outstanding youth leaders under 29 in the agri-food sector.
The top innovation in each of the five categories will receive a plaque in recognition of their achievement and will be featured in a promotional video. All recipients will have access to the Excellence in Agriculture wordmark to be used for marketing and promotional purposes, and up to 15 honourable mention recipients will receive a certificate. For details, visit http://www.omafra.gov.on.ca/english/ excel_agric/index.html
Source: OMAFRA
CLEANFARMS PESTICIDE PICK-UPS CONTINUE
Cleanfarms is running its 2019 collection program for unwanted pesticides from farmers who want to dispose of them safely. Operating on a regional rotating basis, remaining collection events are in the following locations:
• Peace Region of B.C. and Alberta (Oct. 16 to 18);
• Northern Alberta (Oct. 7 to 11)
• Manitoba (Oct. 21 to 25)
• Ontario (Sept. 20
to Oct. 1)
• Newfoundland (Oct.15 to 17).
The Canadian nonprofit organization helps farmers and their communities safely manage farm waste, including small and large plastic pesticide and fertilizer containers, seed and fertilizer bags, and twine. Cleanfarms runs the unwanted and old pesticides and livestock/equine medications collection program in provinces or
Mucci aquires Orangeline Farms
Mucci Farms has acquired Orangeline Farms in Leamington, Ont., including its existing facilities, and additional land with plans for expansion.
“It’s an exciting time for the company as we continue our aggressive expansion plans to increase our local and regional production,” says Bert Mucci, CEO. “The Orangeline acquisition comes with a 32acre greenhouse and a warehouse with additional land totalling 100 acres. Consumers are demanding more local production, and we’re listening. We also have plans in place to build on the additional land that was received as part of the agreement.”
Founded in 2000 by the Kniaziew family, Orangeline Farms is an award-winning grower known for their unique peppers grown under the Zing! Healthy Foods brand. Duffy Kniaziew, founder of Orangeline Farms, will stay on board to lead the Orangeline facilities. Source: Mucci Farms
regions of the country every three years at no cost to farmers. Materials accepted in the program include old or unwanted agricultural pesticides (identified with a Pest Control Product number on the label); commercial pesticides for golf courses and industrial and commercial pest control products (identified with a Pest Control Product number on the label), among others.
The program will not accept fertilizer, diluted solution, large quantities of unopened product, and treated seed, needles/sharps, aerosol containers, premises disinfectants/ sanitizers, and any other household hazardous waste. Any questions can be directed to 877622-4460, or email Cleanfarms at info@cleanfarms.ca.
Source: Cleanfarms
BY THE NUMBERS
Plants use photosynthetically active radiation (PAR) between 400-700 nm
Photosynthetic photon flux density (PPFD) measures PAR in 1m2 per second
Extending from a 12 to 24-h photoperiod can increase lettuce fresh weight by 40%
(University of Connecticut, LumiGrow)
Lighting with 50 µmol/m2/s blue light for 1h can improve lettuce fresh weight by 15%
(University of Florida, LumiGrow)
Big vigor for big pots
Rockin’ Blue Suede Shoes Salvia
Like the other S. guarantica hybrids, this is a refined, well-branched plant with extraordinary crisp blue flowers that pop against black calyxes. A striking landscape plant and a pollinator magnet. Will reach 76-102 cm in height, with a spread of 30-41 cm wide. Best in sun to part-sun with a vigour rating of 2. provenwinners.com
Sunstanding Jazzy Hybrid Impatiens
Sunstanding Jazzy hybrid Impatiens from Dümmen Orange is a new subseries within the well-known Sunstanding series. Jazzy is available in a bold collection of three bright, jewel-tone colours contrasted against vividly variegated foliage with strong retail appeal. A tidy habit makes Jazzy appropriate as an accent plant. Medium vigour, suitable for sun or shade. dummenorange.com
Ideal as a textural accent, this variegated Swedish ivy is a great choice for shade plantings and containers, in addition to being adaptable as an indoor plant. A quick grower, this variety is great for fast-turn combos. Trailing habit. 15-20 cm tall, 30-45 cm wide. syngentaflowers-us.com
Jamesbrittenia Goldstar might just be the little black dress of combos. The sunny, brightyellow blooms go with everything! Its trailing habit makes it an ideal addition to baskets,
This Floribunda rose produces florescent pink flowers that bloom early and continuously from spring to frost. It is very similar to the variety ‘Brick House’, and maintains a bushy
habit in both containers and in the landscape. It has displayed excellent disease resistance for the type on both coasts. Very slight fragrance. Full sun. 0.8 m high, 0.8 m wide. starrosesandplants.com
combos and window boxes. This variety has enhanced resistance to foliage disease. It’s also day-neutral and extremely heat-tolerant. danzigeronline.com
Hydrangea macrophylla Kanmara Blue
A new generation of hydrangea with large, majestic blooms. New for 2020 is Kanmara Blue, which radiates glamour and is sure to steal the show. These shade-tolerant, patio
hydrangeas are a great fit for the terrace, doorstep or balcony. Flowers well into late-summer or fall. Upright habit. 51-61 cm tall, 86-91 cm wide. ballingenuity.com
The 1” single round flowers are a lovely shade of orange with just a hint of red in them (that comes from the parent ‘Red Robin’). This orange variety holds its colour in the heat longer than ‘Mango Tango’. Beautifully compact, it forms a
rounded shrub reaching only 0.6-0.9 m in height and spread, making it perfect for the foundation. How many shrubs bloom all summer like potentilla? Deer-resistant. Bred by Jeffries Nurseries. Rated zones 2 to 6. baileynurseries.com
Pink Brick House
Plectranthus coleoides
Jamesbrittenia Goldstar
Mandarin Tango Potentilla
Experience more than just plants
Transform the garden centre experience into an event-filled, family outing.
The habits of shoppers have changed. These days, customers are looking for experiences that are more than just the products and goods on offer.
In Canada, some garden centres have taken this into account to make sure that they are year-round destinations for shoppers. Having other reasons to visit your garden centre can increase foot traffic substantially and provide you with new income streams.
ABOVE
The busiest time for a garden centre may be in the spring, but there are other ways to help transform this space into a family destination year-round.
Here are just some ways to help you transform your garden centre:
MAKE IT EXCITING FOR CHILDREN
On weekends, families that want to go shopping need to make sure that the kids will be able to come with them. Creating a soft play area with childcare is a great way to make the shopping experience for parents more comfortable. Parents can rest easy in the knowledge that their children are safe and looked after. Not only will parents be more inclined to buy product, they will also have more reason to come to your garden centre over another because of it.
GIVE PEOPLE GOOD FOOD
Walking through a garden centre can be tiring, and offering somewhere to eat is a great way to keep your guests there for longer and to even make your centre an entire day trip for families. These days, however, it’s not enough to give
them a few snacks and a coffee, so consider partnering with a restaurant that offers quality food all day. The right partnership will draw in more customers for both businesses. Those that are there to eat will shop and those that are there to shop will eat. A garden centre is already a picturesque setting, making it a great place for a restaurant.
PLAY HOST TO EVENTS
Hosting events throughout the year is a great way to make new customers aware of your business and to have people return to your garden centre.
When it comes to events, there are endless opportunities. Running gardening courses is not only something that you can charge for, but your students will also want to buy products from you as they learn about their gardens.
Partnering with local producers can allow you to set up monthly or weekly markets with local goods. Themed markets are great events to have through the fall and into the winter, especially before Christmas.
The more creative you are with your potential partners, the better!
If you have the space, your garden centre could even be the perfect place for yoga classes. Offering cooking classes can also be an accompaniment to selling ‘grow-your-own’ kits.
THE BEST YOUR BUSINESS CAN BE
It can be daunting to run a business that can be clearly seasonal, with its busiest time in the spring. There are, however, endless ways to draw customers in all year-round.
Customers are increasingly looking for an experience over and above just purchasing items, and owning a garden centre puts you in the perfect position to offer this.
One of the most important things to keep in mind is to be extremely thorough in your research before you get carried away with your ideas. Hosting events or classes is a great idea, but you will need to host what is right for your local customer base. Find out what they want and offer it. If you can do that, your garden centre will be set up to thrive!
Anthea Taylor is assistant editor at Dynamis and writes for all titles in the Dynamis stable including BusinessesForSale.com, FranchiseSales.com and PropertySales.com as well as other industry publications.
Uncovering a delicate balance
Sight unseen, small microbes play big parts in the root zone below.
When it comes to root zone management, water and nutrients most likely come to mind, but there’s one component which doesn’t receive nearly as much attention.
Sometimes known as ‘root zone microflora,’ the term points to both disease-causing pathogens and good microbes that can benefit the crop.
With beneficial microbials, there are a few basic modes of action, explains Dr. Youbin Zheng, professor at the University of Guelph and known researcher in the field of controlled environment agriculture. They can compete with pathogens for resources, produce antibiotics, parasitize or attack other microbes and colonize the rhizosphere, he says. Some beneficial microbes can even help trigger the plant’s innate defences or promote crop health.
But ridding the root zone of bad microbes can be difficult without harming the good ones. Zheng points out that residual activity from some water disinfecting technologies can kill off good microbes in the root zone. “But having said that,” he continues, “when we grow plants normally, either for vegetables in rockwool or ornamentals in coco [coir] or peat moss, those substrates or their root zones contain a lot of organic matter,” which can tie up any disinfectant residuals such as ozone or chlorine coming from the disinfected water.
Another way is to create a good root zone environment for the crop, using a comprehensive approach known as ‘integrated root zone management’ (IRM). “If you manage your root zone well, your plants are healthier and stronger,” Zheng explains. Similar to the concept of integrated pest management, the goal of IRM is to optimize the root zone environment through different components of production, including growing substrates, containers, irrigation and so forth, to achieve the right oxygen content, nutrient levels, pH – in other words, the right environment for healthy roots. “Say you water too much,” he says, that creates a low-oxygen root zone environment conducive to Pythium, which could eventually lead to root rot.
“...make your system more resistant, more resilient to pathogens.”
As for the pathogens already established in the root zone, not many technologies can get rid of them, Zheng says. Water-sanitizing methods may remove harmful pathogens from the water and nutrient solution, but their spores exist everywhere – in the air, in the substrate – making complete disinfection very difficult.
One approach is to create an ecosystem. At the beginning of each crop, the root zone starts off with low levels of microorganisms – that’s when a grower should consider applying beneficial microbes. This gives the good guys a head start, colonizing the space so they can better compete with harmful pathogens later on. “Start clean, introduce your beneficial microbials first, [and] make your system more resistant and more resilient to pathogens,” he says.
For researchers, the challenge is to find and isolate beneficial microbes to target different pathogens. However, these microbes must be active in the crop’s root zone environment. In greenhouse soilless production, for instance, the target pH is between 5.5 and 6.25, says Zheng. That means an isolated microbe found to work against Pythium in the lab can only be used in the greenhouse if the microbe can survive and perform under low pH conditions. The best approach is to optimize the root zone environment for that particular crop, then choose a microbial product that would work best against the pathogen in question, he says.
Zheng’s team has just finished part of a collaborative study with researchers at Laval University. Having previously tested six commercially available biocontrol products against Pythium without success, the team began to try applying fish sludge to potted gerbera. A combination of fish excrement, uneaten fish food and water from local fish cultivating facilities, fish sludge is rich with microbials. Performing their trials in the greenhouse, researchers found that weekly doses of fish sludge were able to reduce or control both Pythium and Phytophthora The next step would be to isolate the microbe or combination of microbes responsible.
Critical values of various water treatment residues are available for different crops and pathogens. Visit http://www.ces.uoguelph.ca/water/pathogen.shtml
MIXED CONTAINERS: A grower’s guide to getting it right
If you want to grow the best mixed containers, don’t make them an afterthought.
BY MELHEM SAWAYA
As a bedding plant grower, you want to grow the item that is most profitable. Unfortunately, demand for that item could be limited. We only can grow items that are in demand and work to make them as profitable as possible.
With the popularity of mixed containers, we need to produce excellent combinations at the most effective cost. The following guidelines are meant to help you achieve that.
To produce a profitable product and ultimately a profitable business, it’s important to understand the product you are trying to achieve and plan every step ahead of time.
PERCEIVED UNDERSTANDING OF MIXED CONTAINERS
Leftover liners: Gone are the days
when you thought you could put together leftover plants from other plantings. Combinations are planned crops and not an afterthought.
Last-minute trailers: If you are short on availability and you put in a couple of trailing plants as a quick fix, you will end up with a patchedup inferior product that increases your chances of losing your orders for the next season.
Magazine pictures: If you’re taking a picture from a magazine or a breeder’s catalogue and making it the basis for most of your production, the results will not turn out the same way as the picture in many cases. Plants typically do not survive together long – the combination looks great for one week, then falls apart. Cultivars can clash, and
ALL
PHOTOS FROM: M. SAWAYA
the more vigorous varieties can take over. In those cases, the four- to six-variety combinations end up as two- to four-variety combinations, and those can sometimes become one-variety combinations. First try the magazine picture on a small scale and see how it works for you and the consumer, then expand on the program if performance and profit are both favourable.
Your favourite cultivar: Many combinations have to include a certain cultivar because it is your favourite. Other cultivars are thrown in with it, regardless of whether they’re compatible. Customers have different preferences and we should avoid forcing our personal tastes on them, or else we might end up with larger recycling piles.
A cultivar surplus: Computers are great tools, but adding an extra zero to an order can happen easily and often, so the surplus ends up in every combination. Remember that correcting any mistake at an early stage is the most cost-effective approach. The ultimate goal in dealing with the surplus is to increase sales rather than to hinder it, especially at a time when growing area is at a premium. To deal with the surplus, you could use them in some combinations but only if it enhances them, try to sell the surplus or part of it, and/ or spread the surplus over different pot sizes that you are already growing. If none of those options or other solutions meet market demand, then it is much more cost-effective to discard the extras
at the propagation stage.
THE DEFINITION OF A MIXED CONTAINER
Every grower should have their own definition of a mixed container (combination). It is similar to a mission statement for your operation, which sets the basic standards or principles for your combinations.
The definition that I would use for my combinations is: a group of two to four cultivars (varieties) that would grow and look better together in combination than they would separately, while generating higher profit margins.
There are several different ways of approaching mixed containers:
– Two to four cultivars of the same genus, such as three petunias or three calibrachoa of different colours that have the same growing habit.
– Two to four genera per container, such as a combination of petunia, calibrachoa and verbena, or a combination of lobelia, pansy and bacopa. Just make sure you are selecting genera that grow under similar cultural conditions. – Colour-coordinated varieties that are becoming very popular, because they are intended to match certain window shutters,
ABOVE
All varieties remain visible in this combination after 22 weeks.
Propagation Trays
doors and or patio furniture. Make sure the combination meets the standards you set.
– Leaf size and texture coordination, so that one variety doesn’t take over the whole container.
– Monochrome of different cultivars to match lawn furniture, occasions like weddings, buildings, restaurants or any other business.
PRODUCTION
Media: Whether it is a combination or any other crop, potting media should be tested by an independent testing laboratory before use. This is mainly done to find out if the pH of the media is where you want it to be. My preference is to have a pH between 5.5 and 5.8, since 90 per cent of the main cultivars in combinations are petunia and calibrachoa. This pH is not the best for geraniums, but on the other hand, geraniums don’t belong in any combination. By July, the geranium tends to be totally dwarfed by the rest of the cultivars. Soil EC should be between 0.6 and 0.7, tested using 2 parts water to 1 part media, by volume.
Water: Water liners or 4” pots with fertilizer of 1.5 to 2.0 EC before planting. Be sure to water the media before planting to avoid overwatering afterwards. This will help prevent plants from being buried. Water lightly after planting until plants are well-established.
Fertilizer: Using your fertilizer, adjust your pH to 5.6-5.8 and your EC to 1, testing with 2 parts water to 1 part media. To change the pH of your media, use the following:
• Acidic: 18-9-18
• Alkaline: 14-0-14
• Neutral: 17-5-17
Knowing your crops and what they prefer makes the difference between an ‘ok’ crop and an excellent one. Only by testing the soil will you be able to catch fertility variances before it becomes a problem.
Light: Whether it is a combination or one straight variety in a pot, light is very important. Leave room around the containers so that all of the plants in the container are exposed to light, especially when there are plants trailing down the sides. Containers can start pot-to-pot and then be spaced out to finish.
Temperature: Any crop should be started at warmer temperatures of 1820°C, then finished cool. Some crops can only go down to 5-6°C, while others
Choose combinations for simplicity, performance, easy care and elegance.
shouldn’t go below 13°C. When planning your combinations, pick cultivars that are temperature compatible. The worst scenario would be to grow a cool-loving variety that trails warm – the petunia, for example. Some crops cannot take cool temperatures, such as ipomoea or hibiscus (annual and perennial).
Pest control: During spring production, many cultivars tend to be growing at once, which makes pest control an interesting task. Many steps need to be taken, including:
– Starting with clean plant material
– Knowing potential pests that a crop can attract
– If biologicals are used, treat preventatively
– If chemicals are used, monitor very closely and treat accordingly
– Many times, a crop has to be cleaned
chemically before biologicals are introduced. In this case, knowledge of your chemicals is important so you can use ones that are safe-to-moderately safe for the biological that you are planning to use.
– Most of the time, both chemical and biological pest control need to be used in a way that complements one another.
– Try to have your pest treatments applied before flowering time, or at least three weeks before shipping, because flowers are generally more sensitive to chemicals than foliage.
Liners: All planted varieties should have been rooted in the same media.
Programmed liners or 4” pots are ideal, while Elle guard liners are the preferred choice. In addition, liners should be active, alive, and not yellow. They should
ABOVE
not be doped with PGRs, not crowded, not just pinched and finished in full light.
COSTING
Profitable greenhouse operations know the cost of every product they produce, that is, if they sell it at a profitable margin. The costing
process should be divided into four main categories: direct, indirect, shipping and shrinkage.
Direct costs: They include the following inputs:
– Pot or container and including all its parts, such as the hanger and saucer
– Growing media per pot
means taking the cost of whichever media size you bought and actually filling the container you are trying to cost until the whole unit is used. Divide the cost of the media unit (whether it is a tower, half a tower or a 4, 6 cubic foot unit) by the number of containers filled. If you are mixing your own media, you must calculate the cost per cubic foot or cubic metre and know how many containers a cubic foot or cubic metre will fill. Many growers make the mistake of guessing on this calculation, because they figure that the cost per container is small. But when you multiply this cost by the total number of containers grown, then it is no longer a small cost. When calculating the cost per unit, use four digits after the decimal. For example, if your cost for 8” pots is $100 per 60 pots, then the cost per pot should be $1.6667.
– Plant material whether it is a liner, a plug or a 4” pot, the cost of any of these units should be included in total plant material costs.
– Product enhancement This could be supporting rings, stakes, care tags, UPC labels, or clips, and let us not forget the ‘Grown in Canada’ sticker.
– Growing area should
be calculated in sq. ft. each week, which is the amount of space that each container occupies in sq. ft. for however many weeks. Total growing area is a sum of three different stages: pot-to-pot for so many weeks, then at half space for another few weeks, and then final spacing for so many weeks.
– Crop maintenance: Fertilizer use could be figured out in different ways. If it is a mono crop, then it is easy to take the cost of the total fertilizer used and divide it by the number of containers. If fertilizer is wasted on the ground it is still a cost. If it is multi-crop, take the total cost and factor in the different fertilizing frequencies before you divide by the total number of pots for every crop. Include water usage costs, even if it is minimal.
Pest control is becoming a bigger cost than it used to be, ranging from one per cent to 10 per cent of the total cost. This includes insecticides, fungicides, and biocontrol.
Labour costs for crop maintenance should include wages for watering, spraying, crop monitoring, pinching, spacing and every step that is involved to keep the crop in its best form. ABOVE
Choosing cultivars that complement each other makes economical sense and provides better performance in the long run.
The calculation should include every step taken in seconds and not minutes.
When you multiply by the total number of transactions, fractions of a second make a big difference.
Indirect costs: They exist independent of crop size and for the most part, they exist whether a crop is produced or not. Indirect costs can include bank charges (the mortgage, operating loan, principle and interest), and management fees, which cover wages for the owners, accountant, consultant, sales staff, and others not directly related to production volume, and of course, different government fees.
Shipping costs: They used to be three to five per cent years ago, but now shipping cost is somewhere between 15 to 25 per cent due to fuel costs doubling in the last 20 years, wage increases, frequency of delivery (smaller orders are delivered more often), truck insurance (whether you own the truck or you lease it), and depreciation.
Shrinkage costs: This should be factored into every crop cost for two main reasons: 1) to have the right amount promised to your customer and 2) to project your actual costs.
Shrinkage costs could be due to inferior crop quality, crop failure, being sold at a much later date than the targeted date which incurs an extra cost, or not being sold at all. The item could also be sold, but not paid for due to pay-by-scan, complaints (more likely to be excuses because sales at the store are slow) or a bad account (the customer did not pay for the product for other reasons).
All these calculations could be put into an Excel spreadsheet and adjustments can be done quickly and easily. You can also make more accurate decisions based on facts and scenarios on paper before they are put into action.
GUIDELINES FOR PROFITABLE MIXED CONTAINERS
Here is a checklist for items other than the ones mentioned before.
Plant live, pest-free plants. As obvious as it can be, we still make the same mistake: plant an inferior product and try to make something out of it. Most of the time we can, but at what cost? It’s much better to solve the problem at the beginning because an inferior starting product not only costs more, but it creates situations involving extra treatments to the entire crop – the good ones in addition to the bad ones.
ABOVE
Use the minimum number of liners per container that will achieve a good product at the shippable date. This will result in :
–A more cost-effective plant, as well as a higher quality combination for the consumer.
–The fewer plants in a combination, the greater the water-holding capacity of the media.
–Fewer growth regulators are used, which translates into lower costs and higher quality product.
Because of the extra space in each container, the good vigorous varieties will have a chance to show off their potential. I noticed in our trials that the same vigorous varieties performed much better where no growth regulators were used. After all, we are growing product for the end consumer who expects lush, vigorous gardens and not plants that have gone through a chemical compactor.
Compatible varieties are very important; not just for ease of production but for economics. A very vigorous plant
can take over the whole combination, so treat accordingly to fit the rest of the varieties in the combination. On the other hand a very compact variety might and most probably will disappear totally, so varieties like this should not be mixed with vigorous ones.
Fertilizer is as important as any of the other factors mentioned. Fertilize continuously, do not over water and check EC and pH of the media. EC should be close to 1 using the 1:2 media:water test by volume. This should be done on a biweekly basis, which is the cheapest way of ensuring healthy plants and avoiding root damage.
Use high calcium and potassium EC’s to control height. This will make water less available to the plants.
Use different fertilizers to adjust minor soil pH: 18-9-18 to lower pH: 140-14 to raise pH: 17-5-17 for neutral pH.
Immaterial of which fertilizer you are using, if the EC is too high the pH will be low. Balance and moderation are key.
Start warm and finish cool. All crops
What is that caterpillar hiding in my pepper?
The European corn borer may be small. Its impact is anything but.
BY CARA MCCREARY AND TRACEY BAUTE
The tale of the European corn borer (ECB), Ostrinia nubilalis, is nothing short of interesting. As the name suggests, ECB is a pest of corn and is present in all major corn growing regions in North America and Europe. They spend the winter outside as fully-grown larvae in corn stubble or other plant material. In the spring, they complete development and take flight, looking for suitable hosts such as corn, wheat, potatoes, hemp and other crops on which to feed and reproduce. But unfortunately, greenhouse peppers may also be one of the hosts they choose.
In peppers, newly hatched larvae (Fig. 1) enter the fruit just beneath the calyx (Fig. 2) and feed on internal tissues (Fig. 3). This presents a significant challenge as the adults are nocturnal (whereby
they present themselves at night, when we are all at home sleeping) and the larvae are protected inside the fruit. Unfortunately, this means there is direct damage to the harvestable part of the pepper plant.
Another wrench to throw in the mix, is there may be one generation, two, or even up to four, depending on the location. In Canada, ECB typically completes one to two generations. In the case of Ontario, there can be areas that experience an overlap of these generations. So why does it matter? The simple answer is, that the more generations there are, the greater the population may be. In other words, locations that have two generations will see a greater number of ECB in the second generation compared to the first.
ABOVE Figure 1. A larva of the European corn borer (ECB) emerges from a greenhouse pepper. INSET Figure 2. ECB larvae enter pepper fruit near the calyx, leaving behind frass as evidence.
1st moth catch Peak flight End
Two-Generation Strain:
1st Generation 110-150 260 - 360 450
2nd Generation 679-744 830 -1100
One-Generation Strain 300 650-700
TABLE 1 Degree Days & Predicted Flight in Southwestern Ontario.
Source: McLeod 1976 and Baute 1999
EUROPEAN CORN BORER PHEROMONE RACES
Let’s talk about pheromones for a minute. Pheromones are chemicals released by individual insects that induce certain behaviours of other individuals. For example, a female ECB may release a sex pheromone that encourages other males to seek her out. The discussion of pheromones leads to another unique point about ECB. There are two different pheromone races of ECB that co-exist in the United States, Canada, and Europe: The E-race and the Z-race. There is also a hybrid race that has evolved from the mating of E- and Z-race individuals that respond to a slightly different pheromone blend than the E- and Z-races. Interestingly, pheromone race may influence host preference. Some evidence suggests that
the Z-race prefers corn and the E-race may also go to other hosts if available. There is also speculation that the Z-race population has been significantly reduced in North America due to the use of Bt corn. This may have allowed the E-race to become more prevalent and is more likely found in other crops such as greenhouse peppers.
MONITORING WITH DEGREE DAY MODELS
The good news is, we can predict the flight of ECB by keeping track of degree days (i.e. heat accumulations). Degree days are calculated using average daily temperatures and subtracting the lower developmental threshold (i.e. the minimum temperature at which a given species can complete its life cycle). In the case of ECB, the lower developmental
threshold is 10 degrees Celsius. To calculate daily degree days for ECB, you can use the following formula:
Degree days = (max. temp. + min. temp.)/2 – 10 (Note: if the maximum temperature is below the lower developmental threshold, this will result in a negative number and ECB cannot develop. Therefore, the degree days for that day will equal 0).
Degree day calculations begin on April 1st of each year. Degree days accumulate over time and these accumulations result in predictable events such as first moth catch, peak flight or end of flight for adult ECB moths. An example is shown in Table 1. With this information, we can maximize the effectiveness and efficiency of management tactics.
MANAGING THE LITTLE CRITTER
Monitoring is a critical part of ECB management. This can be done by diligent scouting, light traps or pheromone traps (Fig. 4). As we lean towards an integrated approach, trapping can also be used as a form of physical management. After all, every moth that is captured is not mating or laying eggs. Additionally, degree-day tracking can guide the timing of trap usage. As the degree days approach the predicted first catch, traps can be set
ABOVE Figure 3. ECB larvae chew their way into the pepper, leaving a tunnel behind.
up. Until you can determine which race is dominant in your area, it is best to set up a trap for each ECB race. When using pheromone traps for each race, minimizing crosscontamination of pheromone lures is crucial to achieve the best results.
So what’s the take home message? Figure out how many generations and which race(s) are present in your area. Traps will help you to determine which ECB race(s) is in your area and whether you experience one peak flight (one generation) or two peak flights (two generations). Begin monitoring degree days on April 1st and scout for first moth capture, eggs and larvae to determine if growing degree days are predicting the stages accurately. Use the correct pheromone blend based on your ECB race. And watch out for those elusive little caterpillars hiding in your peppers.
REFERENCES
Baute, Tracey. (1999).
Assessment of the value of transgenic field corn expressing Bacillus thuringiensis, (B.t.), endotoxins as a management tool for European corn borer, Ostrinia nubilalis (Hubner) University of Guelph, Ontario, Canada. https://www. collectionscanada.gc.ca/obj/s4/ f2/dsk2/ftp01/MQ43139.pdf
McLeod, D.G.R. (1976).
Geographical variation of diapause termination in the European corn borer, Ostrinia nubilalis, (Lepidoptera: Pyralidae), in southwestern Ontario. Can. Ent. 108: 14031408.
Cara McCreary is the greenhouse vegetable IPM specialist, and Tracey Baute is the entomologist for field crops with the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA). For more information, contact Cara at cara.mccreary@ontario.ca.
BELOW Figure 4. An ECB pheromone trap.
A TASTE OF UNIQUE, NEW EDIBLES
1
Breeders
entice home gardeners with varieties not found on grocery store shelves.
BY RODGER TSCHANZ
There are few topics that interest the buying public as much as food. At plant trials, open house attendees are always keen to test out the latest hot pepper. Even the hippest young male is bound to feel compelled to show his worthiness by throwing caution to the wind and chomping down on a pepper heedless of warnings.
To appeal to the 21st century urban horticulturalist with limited growing room, breeders have been introducing more compact plants with faster maturation, great flavour and, in many cases, the added bonus of ornamental value. The edible plants described in the following paragraphs are ones that caught my interest while on my trip to the 2019 California Spring Trials.
MORE TO HARVEST WITH PROVEN WINNERS
A company known for its ornamental offerings, Proven Winners first introduced selections of tomatoes, strawberries and basil to its lineup in 2019. These edibles are marketed under the “Proven Harvest” banner. While the strawberry and basil cultivars from 2019 were easily grown in containers, the high-yielding, flavourful tomatoes were more suited to ground beds. For the 2020 season, two new vegetable introductions were selected for container applications as well as flavour.
The flavourful, Goodhearted cherry tomato [1] matures in 10 to 12 weeks from a rooted liner into a variety of fruit shapes ranging from that of a pear to a heart. It has a
compact growing habit that is best grown in containers where the fruit doesn’t touch the ground.
The other container-friendly addition is Capsicum Fire Away Hot and Heavy [2]. It is the first pepper to be added to the Proven Harvest lineup. The fruit is described as being an attractive bright red when ripe and has more fleshiness than is typically seen in hot peppers. It is a flavourful pepper with a lower spiciness ranking than the usual jalapeño. Its growth habit is compact and mounding.
SAKATA ADDS HEALTHY, HOT NEW REDS
New tomato and pepper releases from Sakata were highlights at their stop in California
Roadster [3] is a determinate, early maturing, salad-type tomato suitable for container growing. In addition to its great taste, this tomato has a “Crimson Gene” which gives the interior flesh an attractive deep red colour with higher-than-average concentrations of the anti-oxidant lycopene. It’s both good for you and tastes good, what’s not to like?
Sakata’s new Early Flame jalapeño pepper [4] is used in the processing world to make Sriracha hot sauce. The 10 x 4 cm-sized fruit has thick, fleshy walls
which quickly turn from a dark green to a deep red colour as it ripens. This plant’s compact habit makes it very containerfriendly and suitable for the domestic market as well as the production of homemade hot sauce.
BURPEE’S EDIBLE COLLECTIONS
Burpee is a horticultural brand associated with all things edible. To help separate itself from the competition, Burpee presents its edibles organized into “collections”. Collection names such as “Space Savers”, “Amazing Veggies”, “Organic” and “Boost – the antioxidant collection” can all be used to target specific consumer audiences. Their Fresh Flavours Program provides branded sleeves (available with French translations on the packaging) for nine types of herbs including “Pesto Party”, Sassy Sage” and “Playful Parsley”. The program is suited to the small- to medium-sized greenhouse grower and is aimed at providing herbs all year round.
New vegetable breeding from PanAmerican Seed has produced some new vegetable varieties for container and ground bed gardening. 3
Mardi Gras [5] is a new series of sweet pepper available in four different colours that all ripen at the same time. Burpee is also currently test marketing a potato in Canada for the container market. They have three unusual potato cultivars, each with a unique potato
skin colour and one with blue flesh that would be attractive to the consumer who likes to grow their own food on a patio. It is expected that these will be widely available to Canadian growers by 2021. (Note: there will be some restrictions on availability in Newfoundland). For production of the potted greenhouse potato, Burpee is recommending an extra deep container such as with the 4” T size.
DARWIN PERENNIALS
WRAPS UP HERBS
Darwin Perennials has come up with a creative way to package herbs with its ‘herb-A-licious’ [6] herb combo program. The themes for this combo program range from flavouring cocktails and various types of cooking to repelling mosquitos from the patio. Although these combinations are not yet available in a production format, the individual components and recipes for the combinations are available online (https://www.darwinperennials.com/PDF/ HerbCombinations_DarwinPerennials. pdf).
PANAMERICAN SEED
The Orange Marmalade [7] sweet bell pepper displays a high degree of resistance to bacterial leaf spot. The large, bulky (10 cm long by 9 cm wide) fruit ripens from green to orange. The plant itself has a bushy habit and requires some staking to help support the large fruit.
Lemon Sun [8] is a new patty pan squash that, in addition to producing small yellow squashes (without green blossom ends!) also produces large quantities of male flowers that are suitable for stuffing with cheese or frying. The squash forms at the base of the female flower and can be harvested and eaten at any stage of its development.
Helix [9] is a new, small-fruited elongated tomato with an indeterminate growth habit and high degree of resistance to late blight. Fruit maturation is expected to start approximately 55 days after transplanting. The fruit’s flavour exhibits a nice balance of sweetness and acidity.
Artemis [10] is another new indeterminate tomato with resistance to a broad range of diseases. The red fruit of this cultivar is round and sweet. Note
that both Helix and Artemis are very vigorous growers and are not really suited to container production. In various Guelph garden trials, it was noticed that the Artemis fruit started ripening one to two weeks earlier than Helix.
Everleaf Emerald Towers [11] is a Genovese-styled and flavoured basil which blooms 10 to 12 weeks later than standard basil. It has short internodes and can develop into a tall attractive leafy plant with a high yield potential. It can reach heights of 90 cm with a spread of only 30 cm.
Newton [12] is a newly released Genovese-flavoured basil that is resistant to fusarium blight. The licorice flavour often associated with fusarium resistance in basil is missing from this cultivar, which may be desirable for certain culinary applications. In contrast to Everleaf Emerald Towers, this cultivar shows a normal bloom habit and growth habit, reaching a garden height of 50 cm and a spread of 40 cm.
BREEDING TO CONSUMER NEEDS
It is evident from this list of new varieties
that the trend towards homegrown edibles is alive and thriving. Plant breeders are diligently working to provide the consumer with a great selection of vegetables that are easy and convenient to grow – whether in containers or in the garden – and enjoyable to consume with new, interesting flavours that may not be readily available on supermarket shelves.
I want to end this article with a look at something quite unique and unusual for the edible plant market. Ball Ingenuity will be selling small tea plants (Camellia sinensis) [13] in the coming year. It will be available as a 40-cell liner or in 10 cm pots. When this was presented as a new idea at CAST, it seemed to receive universal approval from the group I was travelling with. Instructions for processing your own tea leaves were also provided, which not only appeals to foodies, but further enhances the consumer experience even after the product has been successfully grown and harvested.
Rodger Tschanz is manager of the Guelph Garden Trials at the University of Guelph. He can be reached at rtschanz@uoguelph.ca.
Adapting to the evolving needs of today’s consumers
As plant parents look for niche products and neat experiences, IGCs look to fulfill that need.
BY ANNE-MARIE HARDIE
Homes are becoming smaller, lifestyles are busier, and the number of locations for purchasing plants and their associated products have increased. Shoppers can purchase their plant products almost anywhere, including online shops, big box stores, niche urban plant shops, and traditional independent garden centres (IGC).
“Many new plant keepers have their first plant shopping encounters with new urban plant shops that do not identify themselves as ‘garden centres,’” says Leslie Halleck, certified professional horticulturist and owner of Halleck Horticultural, LLC. “Therefore, many of these consumers don’t identify themselves as ‘gardeners.’ In fact, for these new plant consumers, the term gardening itself can become very intimidating.”
“Gardening to some customers can be a negative, it represents labouring and hard work,” says Will Heeman, chief daymaker at Heeman’s. “Customers don’t have to like gardening to like plants. Instead, they can become captivated by the
story of a plant that may fit into a garden.”
To be a part of this shopping landscape, the garden centre needs to be agile and adaptive, transforming its product selections, experiences, and even language used to respond to the needs of today’s shoppers. This begins by understanding what consumers are looking for.
VALUE-DRIVEN PURCHASES
Shoppers are seeking out plant materials and products that respond to their values. This includes native plants, pollinators, locally grown food, and plant nurturing.
Increasing conversations around the importance of local products, as well as a push from environmental groups about the need to reinvigorate these species have provided newfound energy in native plants. “This year we have seen a definite growth in this area,” says Heeman. “Part of it may be because one of our main suppliers has now offered these plants in a larger one-gallon
PHOTO CREDIT:
CHENG
format over previous 3.5” pots, making it easier for shoppers to anticipate how these plants will appear in their gardening space.”
Selecting plants for pollinators continues to gain momentum. Shoppers not only want to add pollinator plants to their homes but are embracing the idea of creating habitats for these species. IGCs can respond to this interest by creating displays of pollinator-friendly, native, and larvae host plants, offering seminars and DIY workshops, and showcasing products like bee habitats and butterfly feeders that will enable their shoppers to create spaces for these endangered species. “If I told someone five years ago to plant goldenrod for monarchs they would have thought that I was crazy,” says Niki Jabbour, author and edibles expert. “But, now, people are actively seeking native plants like goldenrod, which offers nectar for migrating monarchs, and milkweed, a larval food source for monarch caterpillars. People are not only more tolerant about damage from caterpillars, they are actually excited when the milkweed plants are eaten.”
CREATING A SPACE FOR THE LOCAVORE
Food gardening is one area that appears to be penetrating all segments. “We are continuing to see an increasing demand for growing your own foods, whether it’s because [consumers] like the flavour of fresh food or are seeking the reassurance that the product that they are consuming hasn’t been sprayed or contaminated,” says Emily Tregunno, Halifax Seed Company. Tregunno finds that interest has grown in season extension and indoor growing, with consumers seeking indoor set-ups to grow greens, tomatoes, and peppers year round. IGCs can transform their spaces into the go-to location for budding food gardeners by offering both the core products and hardto-find species (e.g. hops, cucamelons, heirlooms), and introducing innovative experiences to explore plants including workshops, events, and seminars.
PLANT PARENTING
The houseplant trend continues to be a strong one. Urban retail shops are jumping on, offering niche locations where shoppers can come in and discover new, exotic plants to adopt. However, this doesn’t mean that garden centres can’t also become leaders in this space. “Many of these new plant keepers and
ABOVE
Special events can help draw in new customers to the garden centre space.
ABOVE
Activities like this succulent bar are interactive, trendy and Instagram-worthy.
indoor gardeners are also completely new to traditional garden centres and aren’t necessarily aware of their presence,” says Halleck. These plant newbies may have developed an interest through social media feeds and are now seeking a space to fulfill their needs. “There is a huge opportunity for garden centres to tap into this growing customer base,” she shares. Instead of gardeners, these new plant keepers have embraced the label and concept of plant parenting. According to
Halleck, plant parents are finding that plant care helps to reduce stress and anxiety, which is one reason why this trend is making waves. In addition, plants are easier to manage than traditional pets, enabling this group of individuals to use their nurturing skills while also creating a beautiful, living space in their home. Tregunno has noticed a rise in demand for houseplants, particularly in the 18 to 35 demographic. “I feel that there are a lot of social influencers out
there who are helping drive this demand. Houseplants are back in vogue again, and it’s absolutely wonderful to see,” she says. Platforms like Instagram and Pinterest have reinvigorated planting, providing a format for shoppers to review, share, and post their plant journeys. For Heeman’s, their Instagram following doubled over the course of four months this year. “We use stories to talk about what is new, how to care for plants, while providing education in the IGTV video format.”
This helps to break down barriers for shoppers who may have previously been intimidated by gardening.
Instagram influencer, author, and self-professed plant parent Darryl Cheng is one of those individuals helping to drive interest in plant parenting. With over 389,000 followers, Cheng’s scientific approach to planting has garnered interest from a new generation of plant parents. Cheng’s journey began four years ago, when his mother asked for assistance in creating an indoor garden. “I began to research plant care, and the language and information were incredibly bland and prescriptive,” says Cheng. “And so, I decided to use my engineering background to take a very scientific approach to plant care, using social media as a forum to share my experience.” Cheng focuses on discussing the relational elements of plant care using Instagram to share his own plant experiences, common questions, and how plants progress over time. “The current way of plant care is looking for imperfections in the plant and suggesting a remedy. I’m trying to bring a more rigorous, scientific approach to it, focusing on the big picture of plant enjoyment,” he shares.
Halleck urges IGCs to embrace these technologies and use them to create an image that allows them to stand out and engage new users. “I see a significant lack of involvement by the traditional garden centre industry in the platforms and spaces in which these consumers are active. Instagram is bursting with images of ravenous plant keepers and collectors, but there aren’t many garden centres making good use of the social media channel,” says Halleck. “I think that is due to a general resistance to adopt new technology, much like the resistance of traditional garden centres to sell online. We’re missing out on these opportunities.”
As experts in the field, IGCs can also differentiate themselves by becoming a
A s growers of high quality young plants from seed and vegetat i ve mater i als, we’re un i quely p ositioned to accommodate the needs of small to m i d-s i zed operat i ons. Here’s w hy .. .
we sell direct: S i nce we sell our plants d i rectl y , we t ake full responsibilit y for the qualit y of each order.
very low minimums: You ca n o r de r as l i ttle as h al f a b ox to meet our m i n i mums. Four or more full boxes sh i p fre e!
we custom package: You ca n mix a n d m atc h plugs and l i ners of var i ous s i zes i n the same box!
enormous listing: M ore than 3,000 var i et i es are offered in multiple tra y sizes personal, attentive service: tentive service: Y’lllk You ’ll ta lk to a real person ev e r y time y ou call !
W e i nv i te y ou to jooi n our g row i n g l i st of sat i sf i ed cu c stomers and ex p er i ence our comm i tment to i nte gr it y, quali ty , and reliable service.
LEFT
IGCs can transform their space to entice budding food gardeners.
trusted resource and plant ally. “People can go online and find products that they fall in love with, like the cotton candylooking pampas grass,” says Heeman. “It’s beautiful, but you can’t actually plant it and have it look like that here [in Canada], because it’s not zone-hardy.” When customers come into the garden centre, he strives to equip shoppers with the skills and knowledge that will enable them to succeed, positioning Heeman’s as a reliable expert in their locale.
TOMORROW’S DESTINATION
Today’s shoppers are looking for spaces where they feel a connection. IGCs can fill that space, but to do so, they need to change the mainstream perception of a traditional garden centre. Factors such as zero-spray, locally grown and owned, and trained and educated staff will help personalize the garden centre to draw in new customers. In addition, workshops, make n’ takes, festivals, and collaborations with local craftsman and experts will help develop loyal customers while also enticing new shoppers to visit the store.
The reality is, today’s shoppers have an infinite number of choices in where to purchase their products. To drive traffic into the store, IGCs can position themselves as a destination. However, most still cater to existing trends instead of creating them – a missed opportunity that should be addressed. “Use social media to educate, influence, and inspire gardening,” says Jabbour. “Connect with millennials through Instagram and Twitter, and integrate Facebook to connect with the older demographic.”
Unlike big box stores, IGCs have an opportunity to create a space that is uniquely their own, including bringing in new varieties, personalizing their workshops, and using a variety of different tools, including social media, to influence and capitalize on new trends. “If we as an industry were more responsive to consumer demands, we could command more of the plant market. I know this because ‘pop-ups’ are happening in our communities across the country,” shares Heeman. “There is so much opportunity in the market that we are simply not picking up.”
PHOTO CREDIT: N. JABBOUR
Keeping it lit – Controlling greenhouse light pollution
Light abatement screens double in keeping your plants and neighbours content.
BY ROBERT HANIFIN
From stoplights to interior illumination, artificial electric lighting is technology that we rely on in our daily lives to help us at work, at home, and everywhere in between. In greenhouse horticulture, we increasingly depend on it for production purposes – to help crops grow on a precise schedule, throughout the year and in spite of varying natural light levels.
Indeed, HPS, metal halide, LED, and other lighting technologies are important tools in greenhouse cultivation for Canada and other northern climates. There was never a time of greater concern than this past spring when Ontario, the Great Lakes, and the Upper Midwest region in the US saw unseasonably cool temperatures and overcast skies, with lower than normal light levels. One greenhouse tomato grower in the Great Lakes region even reported light reductions of over 25 per cent compared to their normal ambient light levels during a particularly dark couple of weeks in May. It is
ABOVE
during times like these when having adequate supplemental lighting proves its worth.
However, the benefits of supplemental lighting also come with drawbacks. Their electrical demands must be properly specified, and the installations be properly made, to avoid creating a fire hazard. Lighting costs for fixtures, installation and use can add up. The escape of supplemental light from the greenhouse is becoming a growing source of light pollution, as the number of artificially lit greenhouse acres increase.
This is especially true for vegetable and cannabis greenhouses that are increasing their supplemental lighting usage, and the rapid expansion of greenhouse-based cannabis production means a lot of greenhouses are lit up after dark. For the most part, the lamps come on after dark to increase overall daily light integral (DLI) for the crops. Growers of light-hungry crops such as tomatoes may need to keep the lights on long after the sun sets, especially during
Cervello RZ is suitable for Canadian winter plantings from the middle of December onward. Cervello RZ gives the highest production of medium and medium small fruits. It has been proven in both Traditional and High Wire cultures. Sharing a healthy future
Cervello RZ F1 (24-240)
• Powdery Mildew
Intermediate Resistance
• Open plant type
• Generative plant type
• Fruits well filled
• Consistent ribbing from beginning to end
Learn more at rijkzwaanusa.com
For Ontario: RZH Canada Ltd | (519) 324 0632
For Quebec: Seminova / Agrocentre Fertibec Inc. | (450) 454 5155
For BC/Alberta: Terralink Horticulture Inc. | (604) 864-9044
Experience ultimate control of your greenhouse with iSii
Hoogendoorn’s next generation iSii monitors and controls all climate, irrigation and energy equipment in all types of greenhouses. The iSii is equipped with advanced controls that work according to the principles of Plant Empowerment, which resulted from Next Generation Growing (NGG) research. This way light, temperature, humidity and CO2 are aligned with each other for a maximum photosynthesis. In addition, to prevent water stress, irrigation is driven by the evaporation energy and water balance of the crop. With the iSii process computer, you set the base for high quality production.
LEFT
The only way to prevent reflected supplemental light is to block it.
the winter months, to reach their target DLI. For cannabis, a 16 to18-hour day length is typically used during the plant’s vegetative growth stage.
WHEN IS IT A PROBLEM?
Nocturnal light from greenhouses can interfere with nearby airport operations, create ecological issues for sensitive animal populations, negatively impact light-sensitive crops in adjacent greenhouse facilities, and disrupt people’s sleep patterns in nearby residential communities. The only sure way to prevent reflected supplemental light from leaving the greenhouse is to physically block it. This is accomplished through the use of horizontal, retractable light abatement screens installed at gutter height (or otherwise above the light fixtures). Vertical, retractable lightrestricting screens should also be utilized along the greenhouse sidewalls to block light from all directions.
LIGHT POLLUTION CONTROL VIA SCREENING
Specialized overhead screens for light pollution are typically single-layer screens with reflective upper and lower sides. The upper side of the screen helps reflect sunlight, preventing heat buildup if the screen needs to be used during daylight hours. The screen’s lower side is always white, to reflect the light from the lamps back towards the crop, increasing the light intensity within the greenhouse. This three-to-five-percent increase in light can positively impact crop growth and yield. The closed structure of the screen provides greenhouse energy savings by retaining the heated air beneath it.
info@hoogendoorn.ca www.hoogendoorn.ca
Make sure to pay close attention to the screen’s humidity transport properties.A light pollution screen with a knitted structure, such as Svensson’s Obscura 9950 FR W, allows humidity to pass through and be wicked across the yarns. While most modern light pollution screens are made of flame-retardant materials, it’s important to ensure that the screen is installed far enough from the lights to avoid fire hazards.
Climate screens that are specifically designed for light-abatement purposes should be installed as an additional layer to any existing shade or energy-saving
curtain, on a separate set of wires, and be moved by its own motor. Control through the greenhouse climate computer is also typically independent of other screens. Double-layer blackout screens meant for photoperiod control can also be closed after dark for light abatement purposes. These screens should have a reflective upper layer, and a white bottom layer. Greater energy savings are most often realized with a multilayer screen. For example, Svensson’s Obscura 10075 FR AB+BW can be used to control light pollution while increasing your potential for energy savings at the same time. This may be necessary if, for example, the greenhouse range is used for both the vegetative and flowering stages of a cannabis crop. When a multi-layer blackout screen is used for light pollution abatement, more active management by the grower is often required to alleviate heat and humidity buildup under the screen.
COST CONSIDERATIONS
When considering light-abatement screens, it’s important to keep in mind that a separate light restriction screen will require its own infrastructure for proper operation. However, it is typically less expensive and causes fewer headaches when a second screen is incorporated into the initial greenhouse design versus trying to retrofit it later. Natural gas suppliers in individual provinces and states often offer rebates for energy-efficient components within the greenhouse, including energy-saving screens, of which light abatement screens can be classified as. Energy screen rebates can typically be applied to both new greenhouse constructions, as well as the replacement of worn screens and retrofits that add a second screen, furthering the greenhouse’s potential for energy savings.
LEGAL RESTRICTIONS
Municipalities in Canada and the United States are becoming increasingly concerned about light emissions coming from greenhouse facilities after nightfall. These complaints are not limited to a single area, with concerns being raised from New Hampshire and Pennsylvania, to Ohio and Michigan. In Canada, this issue is mainly in the Leamington, Kingsville and Niagara regions of Ontario, as well as in other provinces like Alberta and British Columbia. While active regulations are currently only in place in a few selected areas, the dialogue is ongoing between governing bodies and growers, and
ABOVE
A light abatement screen (Obscura 9950 FR W) is closed over a lighted tomato crop
ABOVE
To effectively reduce greenhouse light emission, a light abatement screen with a white bottom layer is advised to increase the light intensity in the greenhouse.
some growers are voluntarily taking light abatement measures.
The concern is becoming widespread enough that it would be prudent for growers planning new builds or expansions to consider their location and make plans accordingly. Greenhouses within larger industrial settings may not receive as much attention with respect to the use of supplemental lighting as those in more rural or residential areas, and thus are recommended to carefully consider light abatement solutions.
BE NEIGHBOURLY, AND YOUR OWN ADVOCATE
Growers and greenhouse managers should maintain dialogue with their neighbours and local governments regarding the topic of light pollution. Always be a good neighbour and actively participate in any
conversations on the regulation of the light coming from your greenhouse.
Existing regulations in the Netherlands allow for screen gapping and some allowance of light – this was a needed compromise that allows growers to maintain control over their greenhouse climate by expelling excess humidity and heat as needed. This model should be followed in Canada and the US as well to ensure undue burdens do not fall on growers. Concerns over greenhouse light pollution will only increase, leading more municipalities to seek new regulations over time. The ideal outcome is to have light abatement screens with reasonable light allowances agreed to by all parties..
Robert Hanifin is a Svensson climate consultant. To find out more about light abatementsolutions,visit ludvigsvensson.com
EMPOWER PLANTS through balanced climate control
Day or night – how to promote a crop’s self-cooling strategies and improve temperature uniformity under a blackout screen.
BY PETER VAN WEEL
The sun can bring 800 Watts per m2 inside a greenhouse. That is a huge amount of energy, especially considering the total size of greenhouses nowadays. For a 10-ha greenhouse, that equates to 80,000 kW! However, only two per cent is converted by the crop canopy for growth, the other 98 per cent will leave the greenhouse. In that sense, plant production is not very energy efficient.
What is true for sunlight is also true for expensive artificial light, however, lamps bring less energy into the greenhouse. For example, to produce 200 µmol/m²·s, high pressure sodium lamps bring in 114 W/m2 of energy, while LED lamps bring in 74 W/m2. When LED fixtures are water cooled, this energy is reduced to 48 W/m2
What consequences does this have for the crop and the greenhouse when most of this energy must be released again? This article explains the important role of energy balances in a greenhouse and how we can support the crop and the greenhouse in getting rid of these huge amounts of energy.
WHAT IS ENERGY BALANCE?
Greenhouse production is bound to the rules of physics, and one of the most important rules is that energy never ‘disappears’ but is usually converted into different types of energy. For a greenhouse, energy input and output are always in balance. (For more, refer to the first article of this series in Greenhouse Canada, Mar/Apr 2019). The amount of energy absorbed by the plant is less than the energy entering the greenhouse, as part of the radiation is reflected. The plant can actually control that reflection by turning its leaves or by changing the shine of the leaf.
MAINTAINING BALANCE DURING THE DAY
In the graph (Fig. 1) at 1 pm, about 70 per cent of the incoming radiation is absorbed by the canopy. This means that approximately 470 Watts/m2 needs to be converted by the plants.
On warm days, plant transpiration and convection (the movement of hotter air to cooler areas) are the main forms of energy output. Radiation and convection are the main inputs. As soon as the greenhouse air is warmer than the leaf, it will bring convective energy to the leaf in addition to the radiative energy already present. This is especially true for crops with
FIGURE 1
Changes in outside radiation (yellow) and net radiation (purple) over a day.
The amount of energy absorbed by the canopy can be measured with a device known as a net radiometer. It measures light energy that has entered the greenhouse in the visible and infrared (heat) ranges, then subtracts the energy reflected by the canopy. The resulting measurement is the absorbed energy that must be converted by the plant to make the energy balance equal. So, the plant has its own energy balance to maintain.
high transpiration rates. So at that moment, transpiration is driven more by convective energy than the radiative energy absorbed by the leaf. But since transpiration fluctuates as it is controlled by stomata opening, the leaf can also become warmer than its surrounding air. In that case, a large leaf area in combination with air movement will help the leaf dissipate a part of the absorbed radiation energy, thus lowering transpiration. In some cases, this reduces transpiration so much that it saves the plant from water stress.
So far, transpiration models do not take this important factor into account, but for many potted plants, this method
can be very beneficial to their survival. Air movement is therefore very important in a closed greenhouse as increased air movement will reduce transpiration under high radiation. Usually, transpiration is the plant’s main output converted from absorbed solar or lamp radiation. So, it is very important to keep transpiration going over the course of the day. But very often, the wrong ventilation strategy is chosen to release heat from the greenhouse.
By ventilating too much, relative humidity (RH) will drop to under 60 per cent. This increases transpiration to such a high level that the water balance will be disturbed. In the afternoon, there is not enough water available in the plant, and the root system cannot replenish it quickly enough to keep
transpiration going at the required level. The stomata opening will then reduce in size, and the leaf temperature will rise. At that point, convective energy exchange will often save the plant, but photosynthesis will no longer be optimal because CO2 will have more difficulty passing through the reduced stomata opening. To prevent this situation, the RH in the greenhouse should be raised. This can be done in two ways. First, when the ventilation opening is reduced, RH of the air will rise, thus increasing the amount of heat (enthalpy) in the air. A lower volume of air could then be released from the greenhouse to get rid of the same amount of energy. This way, greenhouse temperatures will not rise as much. And because of the reduced ventilation, less CO2 will be lost to the outside world.
The second method is even better: use high pressure misting to increase the RH of the greenhouse air. With this equipment, part of the solar radiation absorbed in the greenhouse will be converted as the fine droplets evaporate. Evaporation converts a lot of energy – 2256 kJ per kg of water. A radiation of 100 Watts/m2 for one hour is equal to 360 kJ. This means that for the conversion of this amount of energy per hour, 160 grams of water must be misted per m2. The plant will then reduce transpiration by the same amount to maintain balance.
BALANCE AT NIGHT AND IN THE DARK
When there is no light, the amount of energy absorbed can be less than the amount emitted. The plant loses energy as it is radiated upwards towards a cold greenhouse roof. That can be seen in the graph (Fig. 1), where the value is negative after 18:00 hours (right axis). That is a dangerous situation because the canopy will have a temperature far below its surrounding air. This situation can result in a loss of transpiration, which will stop the transfer of calcium and cause weakened plant cells. Also, condensation can occur, resulting in botrytis development. A sudden drop in transpiration can also lead to ‘guttation,’ where the warm roots keep pumping water and push it out of the plant cells at the top of the canopy. This causes plant cell damage in that area and can later be infected by botrytis.
The best way to prevent this problem is by making the surface above the canopy warmer, by pulling a screen or by using overhead heating pipes, for instance.
By far, evaporation is the most important way to convert the absorbed energy. Transpiration of water requires a lot of energy and is a very efficient way of conversion.
FIGURE 2
Temperature differences under a blackout screen caused by screen gaps.
FIGURE 3
Reduction of temperature differences under a blackout screen by using an airtight screen, air injection fans and a central release of warm humid air.
BALANCE AT NIGHT WITH ARTIFICIAL LIGHT
Prevention of light emission traps the energy produced by the lamps under the blackout screens. Screen gaps are usually opened to prevent a rise in temperature, but this has a very negative effect on the horizontal temperature distribution across the greenhouse.
Because of the slope in the screen, warm air gathers at the highest point in the middle of the greenhouse complex (Fig. 2). There, it will escape through the screen gaps and once it enters the area above the screen, it cools down very quickly. Since cold air is heavier, it will start flowing to the lowest point above the screen, which is the area along the outer wall. Now very cold, this air will drop vertically through the screen gaps, causing localized powdery mildew and a drop in crop transpiration. In practice, the result is a temperature difference of 4 to 8 °C in the greenhouse, mainly depending on the energy capacity of the installed lamps.
This problem can be partially solved by installing vertical screens above the blackout screen, where one vertical screen is positioned along every 30 m of blackout screen. But very often, wind forces will suck air out of the greenhouse on the windy side. These forces will also create large temperature differences and the vertical screens will not help in those situations. The best solution is to minimize horizontal temperature differences in the greenhouse as much as possible, by installing an airtight blackout screen and without opening screen gaps. Warm air is then trapped
growing environment, a simple, flexible, and sustainable control system is crucial. This is why proactive LPs are turning to Reliable Controls. Our nation-wide network of factory-certified
Authorized Dealers will design, install, and commission a comprehensive control system paired with an intuitive, custom-tailored graphical interface. Take command of your precisely-controlled environment. Generate tracking reports and analytics. Reduce your carbon footprint while improving productivity, quality, and serviceability.
To learn more about this cost-effective and Canadian-made solution, please contact a local Reliable Controls
Authorized Dealer near you.
under the screen, so vertically blowing circulation fans will need to be used to push that warm air down in the canopy (Fig. 3). This action has two positive effects. Additional heating below the canopy will no longer be needed to prevent condensation on the lower leaves, thus reducing the amount of energy that would need to be extracted by about 50 Watts/m2, based on standard pipe temperatures typically used. At the same time, the moisture within the canopy is removed without increasing transpiration by too much.
The best solution is to minimize horizontal temperature differences in the greenhouse...
The energy produced by the lamps can be extracted from the greenhouse with the help of fans. Several options are available, from air tubes to air injection fans mounted in openings along the blackout screen. For uniformity of temperature as well as absolute humidity in the greenhouse, it is important to introduce outside air and have it uniformly distributed over the greenhouse area. Also, the release of warm and humid greenhouse air to the outside world needs to be well controlled.
One particular new strategy achieves that by using an air injection fan with a capacity between 5,000-10,000 m3/ hour along every 250 m2 of blackout screen. This introduces dry and cold air from above the closed blackout screen. The greenhouse air is released in the middle section of the greenhouse through local gaps in the screen and individually controllable ventilation windows. In the future, the energy contained in that extracted air could be regained with a cooling device. That will be the next step in operating a greenhouse without fossil fuels.
KEY TAKEAWAYS
The energy input in a greenhouse can result in overheating of the crop canopy during the day, as well as horizontal temperature differences of 4 to 8 °C when lamps are being used under a blackout screen.
Overheating can be avoided through air movement, which helps increase the convective heat exchange of a leaf. Maintaining high humidity during days with intense radiation, either by means of restricted window openings or the use of a misting system, will help the plant keep itself cool by transpiration for as long as possible, and at the same time, keep the stomata wide open to let in CO2
A non-uniform distribution of temperature under a blackout screen is caused by cold air dropping through screen gaps and by wind coming through a porous screen. Installation of vertical screens above the blackout screen and use of airtight screen materials will greatly improve uniformity. However, to maximize these solutions, a controlled system for mechanical ventilation and air circulation would be required.
Learn more about Plant Empowerment
GPE is based on the same principles as ‘Next Generation Growing’ (NGG), developed in the Netherlands over the last 15 years. It has been shown that this approach can deliver significant advantages regarding production and quality, plant health and energy savings for many different crops. For the most part, this can be achieved without additional investments in greenhouse equipment. The basic principles have been further developed, refined and
extended, focusing on optimal growth in a sustainable way and now goes by the new name ‘Growing by Plant Empowerment.’ For more on GPE and the book Plant Empowerment: The Basic Principles, visit plantempowerment.com. Copyrights of text and illustrations: LetsGrow.com, 2019. Peter van Weel was a senior researcher for Wageningen University. He retired in 2016 and is now the owner of Weel. Invent, a private research and development company for greenhouse production systems. Peter is one of the authors of Plant Empowerment: The Basic Principles
BELOW
A net radiation sensor is pictured. The white box below is a wireless temperature/RH sensor.
WAKING UP to a new horticultural light
From sensor controls to vertical farming, this horticultural lighting expert and seasoned researcher reveals what’s new and ahead.
Q&A WITH DR. MELANIE YELTON, VP RESEARCH, LUMIGROW
Horticultural lighting applications have increased exponentially over the past few years. To better understand why and what’s next, Greenhouse Canada sat down with Dr. Melanie Yelton, vice-president of research at LumiGrow.
Q: Where do you feel the greenhouse sector is, in its current knowledge and use of horticultural lighting?
M: Greenhouse lighting is getting more and more sophisticated on multiple levels. Before, growers would put in what they could afford. But now we can do the math to understand how much it costs. If you don’t light or if you light in a subpar way, you’re not getting as much production as you could.
Q: We’ve heard the term ‘Daily Light Integral’ (DLI) a lot. In short, what does it mean?
M: Think about it like rainfall. If we think of light being raindrops of photons falling onto the earth, it’s a measure of how many photons fell down from the sun that day, measured in “moles”. Monthly DLI averages tell us how much supplemental lighting you would need in March if you want the same DLI – and by extension, the same growth rate – that you had in July.
The exciting thing happening in DLI work is with NASA data. We can now look at daily DLI averages for the past five years within 34 miles of any farm in the world. Perhaps a grower can’t afford to make their light levels like July all the time, but we can look at the economics of meeting their optimal DLI 75 to 80 per cent of the time. By supporting those plants through the winter, growers can commit to a grocery store or market and be confident that they’ll make that deadline.
weather tomorrow, and when their lights should turn on and off. Some growers are quite good at it, but it’s time-consuming and takes them away from other tasks.
We have a light sensor that can measure the ambient light coming into a greenhouse and automatically respond to it. Say you’re growing lettuce and you’ve set a DLI at 17. If it’s been a medium-winter day and the sensor has received a DLI of 7, it will supplement another 10 moles of light to meet that need. Another thing our sensor does is it integrates and makes predictions. It uses data from the previous three days to predict what the next day will be. If there’s been a run of sunny days, maybe it won’t light as aggressively in the early morning. It’ll wait and see what the day looks like. If it needs to make up the extra light, it will. We’re looking to integrate more predictive
data from weather sources in the future.
Q: There’s a lot of talk about underlighting. Can a plant ever have too much light?
Q: There seems to be a lot of adjusting going on. Can lighting be controlled automatically?
M: Traditionally, growers would set a turn-off point at a certain wattage for threshold control. From their growing experience, they would think about the weather today, the forecasted
M: Definitely. In an experiment we did at Harrow Research Station this past winter with Dr. Xiuming Hao (AAFC) and Shalin Khosla (OMAFRA), we had two rooms of tomatoes under traditional threshold control at a 300 W/m2 cut-off, and set two other rooms under sensor control at a relatively low DLI of 18.
Traditional threshold control is designed to turn lights off when the light intensity outside exceeds the predetermined cut-off. At the end of the experiment, the average DLI in the thresholdcontrolled rooms was about 27. It was spot-on at 18 in the sensor-controlled rooms. As it turns out, there wasn’t any more production in the higher DLI areas compared to lighting at the right level. The plants can’t utilize it.
In the case of lettuce, overlighting is detrimental. That’s where shade curtains become very important. High-light plants like tomatoes and cannabis are more tolerant to overlighting, but lettuce is very tender and can burn very easily.
Another concern is temperature. HPS lights run hot. It’s more of a concern in cannabis, because they tend to grow closer to the lights. With LEDs, you can actually touch them. I’ve never seen burning, but I’ve seen a little spot of bleaching if the leaf is right on top of a diode, with the rest of the leaf appearing fine.
Q: Is there an advantage to using either HPS or LEDs with sensor controls?
M: With HPS, you had the ability to turn lights on and off and use a pyrometer at the top of your greenhouse to determine the light intensity outside. But to protect HPS lights, you have to let them cool down and warm up and be more cautious with how frequently you turn them on and off. With LEDs, you can turn them on and off in a microsecond without damaging them. They can respond very nimbly in response to the light levels in the greenhouse.
Q: More growers are taking advantage of vertical space these
days. Would lighting be set up any differently?
M: For vertical growing inside a warehouse, you would need a software to designate a consistent DLI for each level. You set the DLI and forget it.
Another stacked situation that we’re seeing more and more of is where people are growing vertically inside a greenhouse, such as cannabis and strawberry growers. The top level gets more light because it doesn’t have the obstruction of the next level over it.
Ornamental growers have that experience with hanging baskets, using the natural differentiation in light levels to have their higher light plants on top and lower light plants on the bottom. If you don’t have those differences but you want to grow the same plants only on different levels, we can put a light sensor on the top level which will measure ambient light and adjust it. The second level is almost like a greenhouse that doesn’t have as good transmission, but the amount of light tends to be relatively consistent. Looking at how much shading occurs from the top level allows us to make calculations. You might have 90 per cent transmission on the top level, then half as much light on the second level of that stack. We can then adjust it to create the light that the second level needs. It’s utilizing the sun, but also being smart about using vertical space that’s available.
Stay tuned for part II of our Q&A with Dr. Yelton, as we look at how light spectrum can be used to tweak crop growth, improve quality and even deter disease.
[Editor’s note: responses were edited for length and clarity.]
Battling Botrytis: A serious disease in greenhouse lettuce
Seeing brown-grey fuzz on your lettuce? It could be mold.
BY GAGANDEEP SINGH BHATOA AND DR. MOHYUDDIN MIRZA
Cloudy and rainy weather during the past months has resulted in many serious outbreaks of Botrytis grey mold in lettuce and in many other crops. This ubiquitous fungus readily attacks lettuce because of the moist, enclosed microclimate created inside the lettuce head. If remedial measures are not taken at the first sign of infection, serious crop losses can occur.
Botrytis cinerea is one of the most devastating and economically important diseases affecting greenhouse lettuce. It is also known as grey mould because it produces abundant fuzzy spores on the surfaces of infected parts. The fungus infects a wide array of greenhouse-grown lettuce, tomatoes, and peppers, as well as some annual
and perennial crops. B. cinerea can infect almost all plant parts, especially tender tissues, wounds, and senescent and dead tissues when moisture is available.
In greenhouses, Botrytis can infect the plant right from the seedling stages and can cause damping-off. As the disease progresses, soft brown rot may appear on the stem and at the base of older leaves. Eventually, the plant wilts and dies. Under humid conditions, fuzzy grey to brown discolouration or tan mold (mycelium and spores) can develop on young leaves deep within the head of the lettuce. Sometime initial symptoms of the disease might go unnoticed as they often occur inside dense leaf canopies. ABOVE Affected lettuce shows fuzzy sporulation with brown discolouration on the leaf margins.
ALL
PHOTOS FROM: G.
SINGH
BHATOA
DISEASE CYCLE
In the greenhouse, Botrytis is a fastgrowing and aggressive plant killer that overwinters as mycelia or sclerotia in plant debris. Outdoors, it survives as mycelia or sclerotia in soil and plant debris.
Sclerotia are resting structures that serve as a primary source of infection. They germinate to produce sexual fruiting bodies called apothecia, which in turn release ascospores (sexual spores) that initiate infection. However, most of the damage is done by air-borne asexual spores called conidia. Under humid conditions, or once conidia have landed on a wet leaf surface, they germinate and form mycelia which colonize the intercellular spaces within plant tissues through trimming wounds or dying older plants. The mycelia then develop sporeproducing structures called conidiophores that produce even more spores, repeating this cycle multiples times during the season.
an “invitation” to Botrytis
In floating hydroponic systems, water can evaporate from open ponds and create more humidity in the greenhouse. Thus, a better dehumidification system is needed.
Practise good IPM: Establish a good IPM approach right from the beginning of the crop. Discard any seedlings which appear to be damaged or weak.
Pay attention to nutrients that cause rapid vegetative growth, such as the use of high ammonium nitrogen especially during low light periods.
End of crop sanitation is also very critical to managing Botrytis. Clean and sanitize greenhouses regularly. Lettuce is grown as a continuous crop and therefore Botrytis can spread easily from the old crop to the new. Develop a strategy to sanitize the greenhouse once a year during the period when markets may be slower.
Spores are not only produced en masse on infected plants, but also survive on plant debris left in greenhouses, as well as in piles of discarded plants outside of the growing area. This repetition of the disease cycle encourages the pathogen to quickly build up disease pressure inside the greenhouse, eventually making it difficult to control this disease.
WHAT CAN GROWERS DO?
Proper climate control is the main strategy for controlling or reducing the severity of grey mold in lettuce and in other crops. Here are some key steps:
Make sure the air is moving: Keep the air moving at the plant’s surface. In normal situations, the air is moved at the top of the greenhouse. Bring the air down, meaning that in addition to horizontal air flow, establish vertical air flow as well. Newer fans are available to move the air in a “turbulent” manner.
Keep humidity and moisture in check: Avoid condensation on plant surfaces by paying attention to the relative humidity and temperature. Know the dew point for your temperature and humidity. If you walk into the greenhouse in the morning and the roof is dripping, then it means that dew has been formed on the cooler plastic surface.
Understand the importance of temperature ramping from day to night and from night to day. If the drop from day to night is rapid or the increase from night to day is rapid, and humidity is high enough, then dew can be formed. That is
Botrytis is a high-risk pathogen, and it has developed multiple resistance to a wide range of chemical fungicides over the years. Repeated use of fungicides with the same mode of action have resulted in the development of new pathotypes of Botrytis. Growers must avoid repeated use of the same fungicides and should consult local extension specialists for specific fungicides recommended in your region. Also check the product label to make sure that a given fungicide is registered for use in your region. Growers can follow FRAC (Fungicide Resistance Action Committee) codes on modes of action of different fungicides. Rotating applications of different chemistries may help in reducing the risk of resistance.
Growers should use approved biofungicides as preventative measures before the problem arises (rather than curative). As per different research studies, biofungicides like Bacillus subtilis, Trichoderma viride and Streptomyces griseoviridis have been shown to be highly effective against Botrytis
References: Smith, T. S. and J.W. Bartok, Jr. (2004); Moorman, G. W. (2011); Asbhee, C. and Krause, M.S. (2014); Pundt, L (2013).
Acknowledgements: The authors would like to thank Denny Black, owner of Neva Farms, Manitoba for sharing his practical insights on this disease from a commercial perspective.
Gagandeep Singh Bhatoa is a plant health care specialist in Winnipeg and Mohyuddin Mirza, PhD, is an industry consultant in Edmonton. Reach them at gaganagrico@gmail.com and drmirzaconsultants@gmail.com
In the greenhouse, the decisions you make today have a major impact on your results tomorrow. Smart innovations like cloud solutions and Internet of Things applications are connecting the greenhouse, while AI learning and Big Data are allowing growers to level-up their cultivation. But, merging all these available tools and data to support your decision-making is complex and timeconsuming. That is, until now.
Grodan presents the award-winning, fully redesigned e-Gro, a revolutionary software platform that allows you to collect and combine the relevant data from your greenhouse and translate it into real-time insights, with 24/7 visibility, anywhere and everywhere. With e-Gro, you are in control and empowered to make informed decisions to maximize your harvest.
Want to see more? Visit us at booth 615 at the
Conference, October 9th & 10th
NUTRIENT TRANSPORT
– A journey to optimal development
Why transpiration and humidity can impact a crop’s nutrient intake.
BY ROM MEIR
Plants are living, breathing and producing organisms. Just like any other living creature, they require nutrients with which they maintain their physiological processes and continue to develop. These crucial compounds are transported around the plant through complex piping systems. Understanding the factors that affect these systems can enhance the well-being of a crop, producing larger, higher quality yields.
In nature, the plant’s equivalent of food is found in the ground with the most basic building blocks being nitrogen, phosphorous, potassium, calcium, sulphur, magnesium, oxygen, hydrogen and carbon. These compounds are taken in along with the water absorbed by the roots, with the exception of carbon, which is absorbed by leaves as carbon dioxide in the air, as part of the plant’s respiratory system.
Nutrients are transported by water moving through the plant, from root to leaf, bringing them to the plant cells in which they are needed. The hollow tubes transporting the nutrient-rich water are called “xylem”, a type of vascular tissue.
UPWARD FLOW THROUGH THE XYLEM
Water molecules are connected by a bond known as a “hydrogen bond”. This type of bond strongly connects the separate water molecules into one body of water. The resulting cohesion means that once water starts to flow, the rest follows, even when seemingly defying gravity.
In order to initiate the flow of water through the xylem, there needs to be an initial force. This is called the “xylem pull”. When water evaporates from the leaves, it causes the rest of the water to be pulled through the xylem. If evaporation were to stop, the pull would stop, nutrients would cease to arrive at their destinations and the plant would no longer be able to continue development.
Therefore, evaporation from the leaves is a key part of plant development. Transpiration is made possible through
two forces. The first, being the sun, or an alternative light source, causes the stomata found on the leaves to open up, thus allowing water to evaporate. The second force is what determines the transfer rate of water to the air – the relative humidity of the air surrounding the leaf.
WHAT IS “RELATIVE HUMIDITY”?
Relative humidity is a measurement of saturation with regards to water vapour in the air. When relative humidity reaches 100 per cent, the air is completely filled with all the water molecules it is able to hold. This is a basic physical property of air, and not one which is lost on growers, most of whom are well aware of the effects of humidity on their crops.
Due to the constant transpiration performed by plants, ABOVE As water is removed from the leaves via transpiration, the flow pulls water up through the plant, carrying nutrients along with it.
the air immediately surrounding a plant is very humid. This is known as the “boundary layer”. In a greenhouse setting, where there are many plants in an enclosed space, the boundary layers overlap, and without proper management, relative humidity may quickly reach 100 per cent.
When the air reaches complete saturation, it cannot contain any more water molecules, which means water no longer evaporates from the plant’s stomata and the xylem pull is broken. When water ceases to flow upwards through the plant, the nutrients cease to arrive where they are needed as well. If this situation lasts long enough, the plant may die. But even if the relative humidity level is later reduced, plants are affected by the lapse, eventually leading to a smaller, lower quality product. This is especially true when it comes to fruits and vegetables, which require larger amounts of nutrients to properly develop.
With all things taken into consideration, it appears that humidity in the growing space is a serious factor affecting the well-being of the plant and the quality of the product.
TREATING HUMIDITY ON A LARGE SCALE
There are two fundamental methods for lowering relative humidity. The first approach is to deal with humidity through heating. As warmer air has the capacity to contain larger quantities of water molecules, heating the air effectively lowers the relative humidity, the air’s saturation level. But heating the air does not actually remove water, it only raises the threshold known as the “dew point”. Saturation will inevitably be reached. Another flaw in this method is that heating may also take a toll on the plants themselves, which require a specific optimum range of temperatures in order to develop properly.
The second approach involves the actual removal of water. The traditional method of humidity reduction is based on a combination of heating and ventilation. On one hand, ventilation reduces the overall water vapour found in the space, while heating increases the air’s vapour capacity. This method is relatively inefficient, and not always effective. Maintaining an optimal temperature is crucial for the plants regardless of humidity, and there isn’t always room to
adjust in order to deal with humidity as well. Additionally, when air is heated, energy is invested into it, and throwing it out due to excess moisture can be extremely wasteful.
Modern agriculture is more conscious of efficiency, especially when it leads to higher quality outputs, while reducing costs. Along with a better understanding of the greenhouse ecosystem, a new generation of humidity reduction technologies have taken the forefront. Dehumidifying systems can actively remove water vapour from the growing space, thus reducing the relative humidity and stimulating nutrient transport in the plants, without resorting to heat.
Designing a greenhouse system in which temperature and humidity are dealt with separately, also gives growers much greater control over the climate in their facility. Allowing for optimal humidity levels to be achieved alongside comfortable temperatures, without compromise, helps ensure plant health and optimal development.
Rom Meir is the content writer for DryGair, a company specializing in dehumidification technology for greenhouses, drygair.com.
Gavita Pro 1700e
The Pro 1700e LED is a full-term light fixture designed to deliver more usable energy while consuming less power. Operating at 645W with an output of 1700 μmol/s, it achieves an efficacy of 2.6 μmol/J. Eight passively cooled LED bars provide broad, fullspectrum and intense light coverage with no fans or moving parts, significantly reducing the number of possible fail points. Dimmable up to 50 per cent without a loss in efficiency when used with the Gavita E-Series LED Adaptor. Components include Philips Advance Drivers, Samsung white LEDs and OSRAM diodes. IP66 rating, FCC and UL8800 compliant. gavita.com
Philips GreenPower LED Toplighting Compact
The LED toplighting compact fits seamlessly into existing HPS connections and trellis constructions, so you can easily switch to full LED toplighting or create a hybrid LED and HPS lighting system with your current set-up. Compared to a 1000W HPS luminaire, the Philips GreenPower LED toplighting compact produces the same amount of light (up to 1800 μmol/s), while consuming 40 per cent less power (efficacy of up to 3.0 μmol/J). The passively cooled module produces much less radiant heat, putting you in control over your greenhouse climate. philips.com/horti
Dutch Lighting Innovation
Toplighting
Fixture
These Toplighting Fixtures are the latest addition to the DLI product family. They are designed to deliver high levels of photosynthetic photon flux (PPF) values with optimally angled vertical light uniformity. The unique design of the lens creates a highly uniform light distribution over the canopy. Fixtures are constructed in a slim waterproof design and suspended above the plant canopy with the easyhang system, making it ideal for low ceilings. With an output of up to 1000 μmol/s and a power consumption of 330W, this is one of the most efficient LED fixtures at 3.1 μmol/J. IP65 rating. dutchlightinginnovations.com
The 315W NXT-LP CMH luminaire delivers optimal lighting both standalone or as a supplement to existing lighting applications. Its ultra low-profile design and low radiant heat output lend itself to vertical applications or where ceiling height is limited. The well-balanced, highly stable spectrum of Ceramic Metal Halide (CMH) lamp technology, delivers a natural white light that helps reduce internodal stretching to produce a stockier, healthier plant during the vegetative growth cycle. This full spectrum light is also ideal for grading and visual comfort within the facility. pllight.com
Planti 1000W DE Illumitex
Driven by digital ballast, the 1000W DE is designed for high photoelectric conversion efficiency, high luminous efficiency, high reliability, and energy savings. This high-pressure sodium fixture offers intelligent digital remote control for communication, dimming and switching. An airfoil lampshade reflector speeds up air convection to increase lamp life, while its multi-toothed housing structure helps promote fast heat dissipation. A unique reflector design ensures uniform light distribution and can be cleaned without removing the bulb. IP65 rating. plantiinc.com
With a PPF of 1700 μmol/s, the HarvestEdge XO is comparable to a double-ended 1000W HPS lighting fixture. Its efficacy of 2.43 μmol/J surpasses that of HPS at 1.8 μmol/J, and is designed for a longer average lifespan of 10 to 12 years, compared to group relamping every 9 to 12 months common to HPS. HarvestEdge XO also starts with a lower initial cost compared to most other LED systems. Its slim, linear form is designed for ease of mounting and reduces shadowing in greenhouse applications. illumitex.com
GARY JONES
It’s time to act
As I write this short column, it’s currently 30 oC here in Langley, BC, and I am starting to get to my personal wilting point. In plant terms, it’s hopefully not a permanent wilting point.
The news recently has included almost daily reports of new high temperature records being set in BC, North America, and cities across Europe. Indeed, the BBC today reported that “July this year was the warmest month ever recorded worldwide, satellite data has confirmed. The assessment was carried out by researchers at the EU’s Copernicus Climate Change Service (C3S). Scientists say it’s the latest sign that Earth is experiencing unprecedented warming. Scorching heat waves saw records tumble across Europe last month, with unusually high temperatures within the Arctic Circle as well. Globally, July 2019 was marginally warmer – by 0.04 degrees Celsius (or 0.072 degrees Fahrenheit) – than the previous hottest month on record, July 2016.” 1 Other recent reports suggest that (despite what some world leaders continue to believe), instead of maybe 20 years or so to get climate change under some ‘control’, we now only have 18 months, based on current climate data. Are you alarmed yet? If we’re not already doing so, it’s desperately time for us to be ‘doing our bit’.
Simply from the economic need, growers have for a long time looked at the amount of energy required to produce their crops.
take a look at this for your specific situation. And then there are the higher energy using crops that consume more than the example of tomatoes.
It’s often said that ‘you can’t manage what you can’t measure.’ So, if you’re not already doing so, maybe it’s time to start measuring. If you are measuring, how do you know how well your system is performing? You need to have some comparisons. Find out where your performance is relative to others in similar situations. This can help you with a feel-good factor (if you happen to be one of the better growers in this comparison), or motivate you to play catch up with those setting the benchmark. But even if you turn out to be the most efficient in terms of energy use, there is always room to improve, so continue looking for those opportunities.
“It’s often said, ‘you can’t manage what you can’t measure.’”
For example, the amount of energy needed to produce a kg of tomatoes is a reasonable indicator of production efficiency. However, this of course turns out to be a very variable figure, depending on many factors such as geographic location, climate, production system, variety, and greenhouse facilities (e.g. screens), to mention a few. I see numbers ranging from 0.64 MJ/kg for greenhouse tomatoes in Ontario, 2 through to 66 MJ/kg in Sweden (IEEESpectrum 3). Do some digging for data yourself, pick an average, multiply by the amount of crop produced and calculate the total energy used in the sector for just one crop. However you look at it, with energy costs rising (and/or availability reducing) you may want to
Years ago, I had the privilege of working with groups of greenhouse growers in the UK in their discussion groups (then called “Study Groups”). Growers would provide crop and greenhouse data (anonymously to other members) and simple comparisons could be made between the performance of member growers, forming the basis for improvement. Similar methods of doing this continue now through web-based (commercial) platforms. However you choose to do it, if you don’t already do so, now is as good a time as any to get going. Your bottom line will likely benefit from it, but perhaps more crucially in the long term, you can start to reduce your company’s climate footprint. This may help avoid it getting any hotter here in Langley, thank you. Speaking of which, I need to get another glass of water to re-hydrate.
1 BBC Science News, August 5th 2019, at https://www. bbc.com/news/science-environment-49238745
2 Pydynkowski, Kara, et al. ‘A Life Cycle Analysis for Tomatoes in NH’, (2008)
3 IEEESpectrum at https://spectrum.ieee.org/static/theenergy-to-create-your-food
Gary Jones is a faculty member at the School of Horticulture, Kwantlen Polytechnic University, Langley, BC. He sits on several industry committees and welcomes comments at Gary.Jones@kpu.ca.
