Greenhouse Management: Why use growing media with active ingredients?

Ed Bloodnick: Some active ingredients improve nutrient and water uptake for plants. Endomycorrhizae, for example, are symbiotic fungi that attach to plant root systems and form an extensive filament network to acquire certain nutrients and water for the plant. About 90% of the terrestrial flowering plants with economic importance in the world host endomycorrhizal fungi. The benefits are that plants grow better, more prolific flowering and fruiting, they adapt quicker when transplanted, they are more resistant to transplant shock and root diseases. Some beneficial fungi and bacteria live in the plant root zone to compete with pathogens. Some active ingredients form large populations around the plant root to exclude pathogens, called niche exclusion. Some also produce metabolites that suppress pathogens. Trichoderma sp. are fungi that exclude pathogens from plant roots. Bacillus subtilis and Bacillus pumilus are bacteria that exclude pathogens, but also produce metabolites that suppress certain root pathogens. By adding these active ingredients into the growing media, the microbes in the ‘living soil’ help to improve the quality of plants by suppressing pathogens that cause root diseases, thus crops have fewer challenges from nutrient imbalances. Growers can reduce chemical fungicides applications and get better performing plants that require less maintenance.

GM: Are they easy to use?

EB: Most active ingredients are packaged in various forms including liquid, powder or granular format. Some of the liquid products can be applied in the greenhouse with injectors through the irrigation system. Most of the powders can be added to water and drenched as a suspension, however, there is added labor and time to apply products in this method and uniformity can be compromised. Products with granular carriers can be added to growing media in the mixing line and at transplanting. You can also have active ingredients already incorporated in a growing media product before you plant, which has some advantages, including saving time and labor, and preventing disease establishment from early growth.

GM: What is tripartite association?

EB: Plants and endomycorrhizae form a symbiosis, which is a mutually beneficial association between two living organisms. Endomycorrhizae attach to plant roots and provide the plant with certain nutrients and water that the plant root system cannot obtain easily. In return, the plant provides the endomycorrhizae fungus with sugars and starches. A tripartite association is when there are three living organisms involved. In field studies, it has been demonstrated that endomycorrhizae and rhizobium partner to improve the growth of pulse plants to improve the photosynthetic rate resulting in greater crop yields. For greenhouse crops, endomycorrhizae resulting in greater crop yields form a tripartite association with plants to improve overall plant growth.

Greenhouse Management: What are some of the fungal foliar leaf spots growers should watch for?

Nancy Rechcigl: Every plant species is prone to different leaf-spotting pathogens, so it is important to become familiar with the ones that could potentially affect your crops, such as:

• Alternaria spp.: Aquilegia, Calendula, Coreopsis, Dianthus, Geranium, Impatiens, Marigold, Pansy, Shasta Daisy, Stock, Vinca, Zinnia
• Cercospora spp.: Coreopsis, Hydrangea, Liatris, Monarda, Pansy, Phlox, Rudbeckia, Snapdragon, Zinnia
• Anthracnose/Colletotrichum: Daylily, Gomphrena, Heuchera, Hosta, Lupine, Snapdragon, Stokesia
• Corynespora spp.: Crossandra, Foxglove, Hydrangea, Ornamental Pepper, Sage/Salvia
• Myrothecium spp.: Ajuga, Begonia, Echinaceae, Gerbera Daisy, Lantana, Salvia, Stock, Verbena
• Septoria spp.: Gaillardia, Shasta Daisy, Phlox

GM: What are some conditions that leaf spots tend to favor? How can those conditions be avoided?

NR: This time of year, leaf spots can be particularly challenging for greenhouse ornamentals since nightly dew provides perfect conditions for spore germination and infection. Leaf spot development favors conditions such as wet foliage, high humidity and poor air movement. Cultural practices such as reducing leaf wetness and spacing plants for increased air flow are important for prevention, as well as proper sanitation practices.

GM: What symptoms should growers scout for?

NR: When scouting for leaf spots, inspect foliage in the lower and interior canopy of the plant, as they may initially develop there due to reduced air movement and higher relative humidity. They can vary in shape and size, depending on the pathogen, but tend to look more rounded and have distinct margins with a colored border. Under certain environmental conditions, some may form small black fruiting structures within the leaf spot.

GM: Why is product rotation so important in preventing foliar leaf spots?

NR: Fungicide resistance can occur quicker in pathogens that produce a lot of spores, like foliar leaf spots. To avoid resistance, include at least two to three products with different modes of action in a rotation program. Programs should incorporate a combination of products with systemic and contact or translaminar activity that maximizes their strengths and leverages modes of action when they are most beneficial.

GM: What solutions does Syngenta offer to help growers prevent leaf spot diseases?

NR: Our greenhouse program for leaf spot prevention includes a rotation of Daconil WeatherStik® or Daconil Ultrex® fungicides applied early in production followed by Palladium® and Mural® fungicide sprays applied on a 14-day interval. For active infections, apply products on a 7-day interval.

Palladium is a combination of two active ingredients, fludioxonil (FRAC 12) and cyprodinil (FRAC 9), for systemic and contact activity on leaf spot pathogens. Mural contains benzovindiflupyr (FRAC 7), one of the most broad-spectrum SDHI fungicides, combined with a reliable industry standard, azoxystrobin (FRAC 11), for control of a wide range of foliar and root pathogens.

“If you can dream it, we can build it,” says Justin Jacobs, key account technical manager at Argus Controls, in reference to the company’s customized, automated environmental control systems for greenhouses. The company’s made-to-order, highly integrated systems include sensor measurement, equipment control, data-logging, alarms and more.

Greenhouse Management: What can customers expect from an Argus environmental control system?

Justin Jacobs: Our software for the systems is built around growing plants. There are several programming options to regulate irrigation, water, specific nutrient delivery, fertilization and just about everything involved in growing. Argus provides systems for large or small operations, and the best thing is, we generally can use most of the greenhouse’s equipment that is already in place, add our customization and fine-tune the whole system to each grower’s operational complexity, size, needs and requirements. We build a robust, user-friendly system and provide the necessary training to use it effectively.

GM: Is all of that technology hard for growers to get a handle on?

JJ: Once growers see the consistent results they get using our systems, they’re pretty happy. And they can monitor and control the system from just about anywhere, which is really handy — especially with something like the coronavirus crisis that we’re going through right now. With our system, growers can let the customization take over if staff is reduced — one of the real benefits of automation. If they have any questions, we provide any additional training needed on site plus have experts on the software who are available 24/7.

“We build a robust, user-friendly system and provide the necessary training to use it effectively.”

GM: Why is Argus a reliable system for growers?

JJ: For one thing, there is a lot of redundancy built into each system to prevent problems, plus there is an option for switching to manual operation. If any issues do crop up, we’ve got a highly trained team of customer service people who can make adjustments on the spot and trouble-shoot with a high degree of specificity. We have a very large, skilled team who know all the ins and outs of the systems. These systems are exceptionally serviceable, scalable and flexible. Because each one is custom-built, we can swap out parts if needed and adjust what is needed on the go.

GM: What else should growers know about Argus’ environmental control systems?

JJ: In today’s market, an adjustable environmental control system is a huge advantage. Many other systems are too stringent, but we can adapt any greenhouse’s business to shifting needs and trends. For example, with the current push for organic products, our systems reduce the need for pesticides and other chemicals. We can adapt to all of our clients’ needs, including system indoor vertical farming, for example. Plus, because of the precision of the systems in delivering nutrients, water, fertilizer, etc., growers can expect to extend their growing seasons and provide fresh plants year-round.

According to Plantpeddler President Mike Gooder, the genetics within the horticulture industry continue to evolve. Gone are the days when a genus was limited to one size fits all. Now, there are lines to fit specific applications. In begonias, this is definitely the case. Below, he discusses the current begonia market, popular traits and opportunities in vegetative and seed grown production.

Greenhouse Management: What is the current state of the begonia market?

Mike Gooder: We see an increasing consumer interest in begonias of all forms. The resurgence of foliage plants will likely play into indoor flowering products. There is an expectation that we’ll see greater demand for indoor-type begonias and the opportunity for growers to expand sales. That most notably will include Hiemalis types, with many other options. On the outdoor side, there continues to be a strong market which is across the board for all types. This includes vegetative material, which is our focus, to improvements with seed types. From personal containers, baskets, gardens and landscapes, to professional and commercial applications — there are begonias which fit every niche and need. It’s a strong and viable market. Breeders continue to develop innovative lines and varieties. New 2021 selections are coming from key players including Beekenkamp, Dummen Orange, Koppe and others. Though a longtime seed breeder, the notable newcomer to vegetative cultivars is Syngenta, offering two new series. It is another exciting year of begonia introductions.

“We see an increasing consumer interest in begonias of all forms. ... There is an expectation that we’ll see greater demand for indoor-type begonias and the opportunity for growers to expand sales.”

GM: What are some of the popular plant traits on the market right now?

MG: The focus is on continual improvements in ease of production, enhanced plant and flower habit, with a keen eye on superior garden performance. The Koppe R’Ilona series is an example of an improved Hiemalis line featuring more natural branching. More branches equal more flowers, but also flowers are held a bit closer to the plant. This allows for better display over the foliage canopy, but also improved shipping and post-harvest in retail and for the consumer. All major breeders are actively trialing for both greenhouse and outdoor performance as part of the criteria. Examples are improved powdery mildew resistance, uniformity and adaptability in use. A major step forward has been in new interspecies crosses bred as true container varieties, thus shaped by design for balanced height and fullness for baskets, mono-culture pots and combinations.

GM: What is the application of rooted-cuttings versus seed-plugs in the production of begonias?

MG: Both forms are viable, and type depends on use and application. When you look at total numbers sold throughout the market, seed types hold the greatest numbers in bedding plant flats and landscapes. Whereas, if you’re looking at the direction of our industry, with larger basket and container production, this is where vegetative genetics shine. begonias in mixed containers can really add a premium to people’s programs. For this application, premium-quality vegetative genetics excel, as they are engineered for this use versus seed types. Whether vegetative or seed, begonias are complex, challenging in propagation, and success of the crop is dependent on a great start. To reduce your risk and increase your success, start with quality liners from a begonia specialist like Plantpeddler.