Photo courtesy of Fine Americas

Greenhouse Management: Why isn’t my ethephon PGR working effectively?

Dudley Dabbs: As we approach summer and warmer temps, we hear from more growers asking for support on ethephon products (such as Collate and Florel), which are used for increased branching. Many of the larger commercial greenhouses prefer overhead boom applications for ethephon where the 6X more concentrated Collate has a better fit than Florel. The increased concentration of the Collate formulation eliminates the boom overwatering issue with Florel because it takes so much of the less concentrated formula to achieve the desired results. In addition, Collate increases storage and shipping cost while reducing the number of containers needed to do the job.

Every year we hear about failures — whatever product they’re using, we get the call. We have identified two of the most common pitfalls to avoid.

First, make sure your spray tank water is buffered so that the pH is between 4 and 5. Ethephon is stable at low pH, but at higher pH levels, it will destabilize and not be as effective.

Second, avoid high temperatures at application. That means making late evening or early morning applications during warm weather so that you can avoid doing applications at temperatures higher than 79° F.

We have confirmed this through Fine Americas-funded studies conducted by Dr. Roberto Lopez at Michigan State University.

If you make sure these two factors are addressed, you can avoid failures and increase your chance of success with ethephon PGRs.

GM: What’s the best way to start tank mixing PGRs?

DD: As growers mature in their PGR use, they often advance to tank mixing two or more PGRs together to achieve the results they’re looking for. Before doing that, it’s very important that you understand what the different PGRs do. Understanding the different plant growth regulators’ modes of action is the first step toward success with tank mixing.

GM: How can I successfully use the Trifecta tank mix I’ve heard about?

DD: Some very experienced users are tank mixing three PGRs — Dazide, Collate and Configure — to achieve the utmost precision: Dazide for height control, Collate for branching and Configure for branching through a different mode of action. These growers have coined the phrase Trifecta as a nickname for this three-way combination.

Using these three products together does achieve excellent results, but it is not for the inexperienced PGR user. It takes great knowledge and careful management to succeed. One of the most critical aspects of mixing PGRs is proper application timing. Using these three PGRs together really optimizes your outstanding plant production if you can achieve the proper plant growth stage timing.

You get the plant to maintenance growth, but you also encourage it to branch and fill out the pot, growing wider than taller. You end up with a tight internodes and lots of breaks — a really tight plant. You get that way quicker and with only one application. These plants have nice architecture while maintaining plant growth.

If you’re really interested in delving into more enhanced PGR use, Dr. Joyce Latimer of Virginia Tech University, Dr. Brian Whipker of North Carolina State University, and Dr. Roberto Lopez of Michigan State University will be presenting a Branching Out with PGRs seminar sponsored by Fine Americas at Cultivate’19, Sunday, July 14, at 2:45 p.m. And you can also attend Managing and Improving Plant Vigor with PGRs on Monday, July 15 with Latimer and Whipker at 9:45 a.m.

Photo courtesy of SAKATA SEED AMERICA

At the 2019 California Spring Trials, Brad Smith, retail category manager at Sakata Seed America, showed attendees SuperCal receiving heavy overhead irrigation in a glass box, and not wearing down. He discussed with Greenhouse Management why SuperCal is a top choice for growers, retailers and consumers.

Greenhouse Management: What is the SuperCal series and what does it offer growers with regard to appearance and performance?

Brad Smith: SuperCal is an interspecific cross between calibrachoa and petunia. It takes what petunia and calibrachoa have that are best, brings that to the market and leaves behind the things that aren’t so great with those different [genera].

From a grower’s perspective, what SuperCal is going to bring to the market is two distinct habits. There’s SuperCal and there’s SuperCal Premium. The SuperCal are more of a multiflora look of a petunia with smaller flowers and it is more semi-trailing. SuperCal Premium is going to be more like your grandiflora petunias with bigger flowers — a little more mounding habit. Those are going to let the grower bring petunias to market at times — not just the peak season when everybody can grow a pretty petunia — but the seasons that are more challenging. For instance, in the summer, when other petunias don’t like the heat, SuperCal still holds up so growers can produce for a late-season crop as well as an early-season crop. They can also go into fall with the SuperCal because you can produce them in the summertime.

From an end-use consumer perspective, it’s all about the performance. SuperCal are going to do fantastic. They’re going to do great once they hit the store. It doesn’t matter if it’s overhead irrigation; it’s high winds; it’s cold; it’s heat. It’s going to look good in the store and, more importantly, it’s going to look good for that homeowner for longer than they expected.

GM: Snowberry White and Lavender Star are new colors in SuperCals introduced at California Spring Trials. What stands out about these colors?

BS: The Snowberry White gives us a great white color that works great in combinations as well as mixes. The Lavender Star is our first true novelty color. It’s an eye-catching color that looks great standalone or in mixes with other plants.

GM: How can growers fit these new varieties in their crop offerings?

BS: I think how SunPatiens has hit the market where there’s not a situation anywhere that New Guinea Impatiens will outperform SunPatiens — sun or shade, spring, summer, fall. I think with SuperCal, it’s the same story. If we offer a color in SuperCal, the grower should use it instead of a petunia because it’s going to perform better for the end user.

GM: Spring Trials attendees also saw a demonstration where SuperCals responded well to heavy water. Can you talk about the performance of SuperCal under these or other difficult conditions?

BS: One of the biggest drawbacks of most petunias is they don’t hold up well in heavy rains or overhead watering. SuperCal isn’t affected by it at all. The blooms stay upright; they’re self-cleaning because the foliage isn’t sticky. Petunias usually have sticky foliage, so when the rains come, the blooms get stuck in the foliage, which leads to Botrytis and makes the plant look all kinds of nasty and mushy. SuperCal won’t do that. It’s self-cleaning and the flowers stay up.

GM: What are some other new advancements in the SuperCal series that growers should be aware of?

BS: We’re continuing to breed in both forms of SuperCal — traditional and the SuperCal Premium — and we have great colors that make for wonderful fall colors as well as spring. So we’ll continue to develop the color line to where, eventually, we can have all the key colors in the spectrum.

Photo courtesy of Benary

Pentas are commonly grown in hot, humid climates and are commonly featured in mixed containers or mass landscape planters. Below, Benary’s Scott Hanes discusses presenting pentas, what makes them unique and more.

Greenhouse Management: Where are pentas most commonly produced and how are they most commonly presented?

Scott Hanes: Native to Eastern Africa and the Arabian Peninsula, pentas are the perfect crop for hot, humid areas like the deep south in the United States. They are most commonly produced in 4.5- and 6-gallon pots, with some growers sowing pentas every week of the year. These tough annuals thrive in harsh climates and provide great color all season long, even becoming perennials in tropical areas (USDA Zones 10-11). Commonly used for mass landscape plantings, pentas also perform well in borders, as specimens or in mixed containers. They even work as houseplants in a south-facing window with enough light and consistent moisture.

GM: What are some of the most popular colors for pentas?

SH: The most popular pentas colors on the market are red, violet, white and pink. These are the core colors, but some others like rose and lavender are also used frequently. Compact hybrid genetics are a lion’s share of the market, although taller types and some native species are still produced commercially. New breeding has led way to more novelty colors, bicolors and other concepts, which are becoming more popular.

GM: What makes pentas unique when compared to other plants?

SH: Their amazing summer performance makes sense as pentas’ growth and flowering is predominantly heat-driven, seeming to only improve as temperatures crank up. Pentas are also one of the best pollinator-attractants you can plant to bring masses of bees, butterflies and hummingbirds all summer long. Pentas lanceolata are even valued as traditional medicines in their native habitats for their antibacterial, antimicrobial and other medicinal properties. One unique feature of pentas is that their roots release H+ ions into the substrate or soil which in turn lower the pH over time. They are extremely iron-efficient plants, which makes them very susceptible to Fe/Mn toxicity and Mg/Ca deficiency at low pH under 6.5.

GM: What differentiates the new Graffiti 20/20 series from the previous generation?

SH: The new Graffiti 20/20 series is a full upgrade to the Graffiti OG (Original Genetics) series, with completely new breeding for enhanced performance, uniformity, timing, and color range. The improved genetics offer one-week faster flowering and perfect timing across all colors. Graffiti 20/20 was bred to have larger florets with wider petals for more color. Our breeding also selected for better branching which provides more flower clusters and nonstop blooming. Now unrivaled in uniformity and speed, Graffiti 20/20 provides the best compact matching habits that perform in production and in the landscape. The Graffiti 20/20 series now has nine vibrant colors including novelty colors like lavender pink, ruby, and flirty pink (bicolor). Mix and match any colors together for an easy summer combo or count on all colors blooming together at retail or in the landscape this summer with these great genetics.

Photo courtesy of Mycorrhrizal Applications

Greenhouse Management: What is the role of mycorrhizae in plant nutrition?

Leonardo Casieri: Outside the root, mycorrhizal fungi develop into the soil by extending their mycelium (hyphal network) and prospecting for nutrients far from the plant. The nutrients are relocated and delivered to the root. They are exchanged with the host plant through dedicated exchange structures. In this trade, the plant obtains mainly water, macronutrients and micronutrients from the mycorrhizal fungi. In return the fungal symbiont receives organic carbon compounds (photosynthates), in the form of lipids and sugars produced by its photosynthetic host. These photosynthates are then transferred and used in the growing margins of the mycelium and developing reproductive structures such as carpophores and spores.

The main outcome of this complex and finely tuned symbiotic interaction, and ultimately the role that mycorrhizae play, is to greatly improve the ability of the plants to gather and utilize water and nutrients, from the surrounding soil or substrate.

GM: Why should growers consider using mycorrhizal fungi to improve plant nutrition?

LC: This mycorrhizal symbiosis directly contributes to plant nutrient availability and utilization throughout the plant’s entire life cycle. Mycorrhizal fungi are capable of accessing nutrient pools in the soil/substrate that are inaccessible to plant’s roots by solubilizing these tightly-bound nutrients and delivering them to the plant. Due to this increased nutrient efficiency, mycorrhized plants need significantly lower amounts of readily-available fertilizers compared to non-mycorrhized ones, which reduces the economic impact of plant nutrition on the overall costs of plant production.

GM: How does mycorrhizal inoculation affect different types of plants?

LC: Mycorrhizal fungi adapted and evolved to interact with different plant species over more than 400 million years. In doing so they differentiated in specific and particular types of mycorrhizae, among which the most important are the Endomycorrhizae or Arbuscular mycorrhizal fungi (AMF), which interact with many flowering ornamentals, vegetables and farm crops, and the Ectomycorrhizae, which interact mainly with hardwoods and conifers. The most efficient mycorrhizal inocula (such as the MycoApply® professional brand produced by Mycorrhizal Applications) have different fungal species either of Endo- and/or Ectomycorrhizal fungi, capable of interacting simultaneously with multiple plants also belonging to different species. This diversity improves the plants’ environmental conditions, giving them an advantage.

More specifically, mycorrhized plants present faster growth and better resistance to stresses compared to non-mycorrhized ones. This might be the critical factor for a successful establishment of plants in a new environment, such as a production container, and for faster and improved plant production in controlled conditions.

GM: What do growers need to know about applying mycorrhizae?

LC: Although mycorrhizal interactions improve plants’ nutrient availability and utilization and reduces the toxic effects of certain nutrients’ excesses, the presence of high concentrations of phosphorous (P) is known to be detrimental for the establishment of mycorrhizae. Therefore, over-fertilization might hamper the capability of the plant to benefit from a mycorrhizal inoculum. Another key factor to establish mycorrhizae is to carefully apply the inoculum as close to the plant’s growing roots as possible, to facilitate the contact with the active ingredient (mycorrhizal fungi) and speed up the development of the symbiotic interaction.

GM: Aside from plant nutrition, are there other unforeseen benefits of mycorrhizal inoculation?

LC: Several studies and field trials have shown that plants’ resistance to abiotic stresses (including drought, salinity, pH, and heavy metals) is greatly increased. Another indirect beneficial effect of mycorrhizae that has been documented in the scientific literature is an improved ability of the plant’s defense mechanisms to be less impacted by pest attacks. This increase in immune response is considered more of an indirect benefit, and may be attributed to the increased overall vitality of mycorrhized plants in general