Greenhouse Management: What are pH and EC?

Isabelle Gagné: Your soil’s pH is the measure of its alkalinity (basicity) or its acidity. An acidic soil has a lot of hydrogen ions (H+), while a basic soil will have a lot of hydroxide ions (OH-). On a pH scale of 0 to 14, 7 represents neutrality (same amount of H+ and OH- ions). Under 7, the pH is acidic and above, it’s alkaline. Each crop has an optimal range, but most of the time the target pH Is between 5.4 and 6.2. It’s important to know that the soil’s pH works according to a logarithmic scale. This means that when a pH measurement varies by one unit, the acidity/alkalinity is 10 times higher/lower. That is the reason why even slight variations in pH can have a huge impact on production.

On the other hand, electrical conductivity (EC) is the measurement of all the soluble ions that are present in a soil. In other words, it measures the quantity of nutrients, which are dissolved charged ions, in the growing media.

GM: Why are pH and EC important to crops?

IG: Plants are very sensitive to pH changes as the acidity of the soil influences the solubility of nutrients. Nutrients can be present in a substrate, but they may not be available to the plant if the pH is not at the right level. As you can see in the image below, for most crops the optimal pH is 5.5-6.0 as it allows maximum nutrient availability in a growing media. Although certain species have particular pH preferences and tolerances, a range of 5.4 to 6.2 is appropriate for the large majority of crops.

This is why the EC is also important. You can view it as a snapshot of the nutrients that are currently available in your growing media. EC measurements can be done easily and regularly. However, you want to make sure you are making informed decisions through reliable data, therefore we recommend you calibrate your equipment frequently and establish a standardized testing methodology. Sending samples to an external laboratory will allow you to confirm that your calibration is adequate.

“You can view it (EC) as a snapshot of the nutrients that are currently available in your growing media ... measurements can be done easily and regularly.” — Isabell Gagné

GM: How can I manage pH and EC?

IG: Three things can influence the pH and the EC of a crop: water alkalinity, fertilizers and the plants themselves. Therefore, to manage both pH and EC properly, you will have to pay careful attention to these three factors.

It is important to know that when we talk about the alkalinity of the irrigation water, we are actually talking about the buffering capacity of the water, or its capacity to resist acidification. Irrigation water quality plays an important role in regulating the substrate’s pH and EC.

Greenhouse Management: Where does BASF suggest ornamental growers begin when building their insecticide programs for the Spring season?

Jen Browning: Try focusing on functional groups. This makes for a simple way to write an insecticide program. You have five main functional groups when you think about insecticides — oils and soaps, insect growth regulators (IGRs), biological insecticides, targeted conventionals and broad-spectrum conventionals.

Oils and soaps will help disrupt the life cycle of most insects and mites to help delay resistance. Look for highly purified oils, (99% unsulfonated residue) for maximum plant safety under the widest range of growing conditions. IGRs also help with disrupting the life cycle of pests, typically by preventing juveniles from maturing into reproductive adults. Each reproductive adult you remove from the population prevents all their offspring from feeding on your plants, so the effect is magnified.

Even if you don’t run a full biologicals program and think that approach isn’t for you, biological insecticides can enhance the results you get with the rest of your program in sprays you’re going to be making anyway.

Targeted conventionals are great for growers who want to preserve beneficials in their ranges, indoor or outdoor, that are providing them with some biological control as predators or parasitoids.

Broad-spectrum conventionals are the “old school” workhorses of the chemical shed. We’ve lost some of these materials over the years, and the ones we have left must be stewarded carefully because they have an important role in our integrated pest management (IPM) programs.

Why does focusing on functional groups simplify the decision-making process for integrated pest management (IPM) in greenhouses?

JB: Choosing solutions from the functional groups for your pests of interest will automatically start the process of rotating your modes of action (MOAs). It simplifies the process of product selection and can keep you from buying redundant products or missing a key functional group that is a heavy lifter in managing difficult pests.

How has the way growers use broad-spectrum conventionals changed over time?

JB: We tend to not use broad-spectrum conventionals the way we used to for every application and without much thought, but we want to have access to them for the important job they do when we need that hammer. Sometimes you’ll need a rescue application at the height of summer when populations are extremely high, for a difficult or large-bodied pest you can’t otherwise control, or when you need to do a clean-up application prior to changing crops in a range.

What are some of the newer approaches growers are trying in their IPM programs?

JB: Targeted conventionals are the newer generation of conventional chemistries. These active ingredients may cover several groups of insects or mites or they may be very specific, such as Sultan® miticide, which only kills spider mites (Tetranychidae), but not mites in other families. The greatest benefit to these types of chemistries is that many of them preserve beneficials and have better pollinator and non-target safety. The trade-off is that you’ll need to be sure of your pest identification. If you spray broad mites (Tarsonemidae) with a spider-mite-specific product, you won’t see any control.

Which functional group should growers use to reduce everyday ornamental challenges?

JB: Biological insecticides work best for foundational applications made weekly to keep greenhouse pest pressures low. These products can include Beauveria bassiana insecticides like Velifer® fungal contact insecticide/miticide or Nemasys® and Millenium® beneficial nematodes.

Greenhouse Management: What trends do you see in the overall calibrachoa market?

Mike Fernandez, market manager — North America: The trend is to breed for early to flower varieties that have tighter internodes to promote more flowering and better branching. Also, breeding for pH sensitivity and always for larger more colorful flowers. All these things will provide a better experience for the end consumer.

GM: What sets Danziger calibrachoa breeding apart from the others?

MF: I believe what sets Danziger apart from others is the location of our breeding. All varieties are bred in Israel and this gives us an advantage for heat tolerant varieties. I also believe that our trialing and testing process around the world gives us more data before introduction. Having our own labs for diagnostics, TC supply and R&D is also a huge advantage. All of these things combined enable us to go to market confident in the introduction. Additionally, having our own supply chain for each market helps to add value for our customers.

GM: What exciting new innovations in this crop does Danziger have in the pipeline for the future?

MF: I believe one of the most exciting things is our initiative to breed controlled growth products. Controlled growth means a plant that grows and looks like it has had plant growth regulators (PGR) but it hasn’t. This will make easier to grow varieties for the grower and a better-quality plant overall. It also lengthens shelf life which is very important to both the grower and retailer. We also have more unique novelties in the pipeline. These are always appealing to consumers.

GM: How can a grower fit these products into their current offerings?

MF: The best way is through trialing. Danziger makes all varieties available for trial free of charge because we believe that this is the best way for the grower to know if it will work for them. Another important factor is for the grower to attend regional trials to see the varieties growing in their own area. Danziger is making a list of these trials available to all growers so that they will know where they can see our genetics at unbiased regional trials.

GM: What can growers do to finish the best cali crop possible?

MF: Although the breeding is for the varieties to be able to tolerate a higher pH, it is still important to know your water pH and alkalinity so you can make the best decision on fertilizer and acid injection as necessary. A good scouting program for insects and pH testing are also key. Knowing the finish timing, correct PGR rates for each variety, overall habit and vigor is all important for finishing a strong and marketable plant.

Greenhouse Management: To what developments do you attribute the recent increase in interest in automation and moving plants via conveyor systems?

Edwin Dijkshoorn: There is more and more interest in conveyor belt systems because of labor shortages as well as the seasonality of the industry. You’re highly dependent on seasonal labor. They say today in the U.S. there are 9.7 million people unemployed, but nobody seems to be able to find good workers right now. This is not just growers either, it goes across most industries. Wages are also going up, too, and with the cost of some of the equipment going down, there is a much faster return on investment today when it comes to automation technologies.

GM: Why do you think U.S. operations have trended a bit behind their European counterparts when it comes to adopting automation in the greenhouse?

ED: In Europe there is a lot of mono cropping. Many of the largest growers produce only one crop or variety, so the labor cycle is more fixed than over here where a lot of the growers are producing multiple crops in the same greenhouse. The mono-cropping makes automation much easier to adapt to your workflow because your employees are completing the same tasks pretty much every day. And then, again, the seasonality of how we grow here in the U.S., as well as all of the different products that these growers are required to use when they produce a crop for the big-box retailers, it can become quite overwhelming for some of them.

“It is all about eliminating plant touches and people steps where you can, and where it makes sense too.” -Edwin Dijkshoorn

GM: Tell us about your SmartFlo 300 system and how it can enable a grower to be more efficient.

ED: It is all about eliminating plant touches and people steps where you can, and where it makes sense too. Here in the U.S. you have greenhouse operations moving plants and/or products in and out of the greenhouse and into the different production bays at a rapid pace. Normally that requires a train of moveable carts and you have employees picking up the plants two at a time and walking them over to the carts. Once the carts are full, they drive the carts to another bay and they unload and space them back onto the floor. With a conveyor system we can eliminate a lot of those touch points and miles walked. The plants now meet the worker in the workspace. It’s much more efficient and it also provides the grower with peace of mind.

GM: Do you have any parting tips for growers who are thinking about adding conveyors but haven’t done so yet?

ED: Take a 30,000-foot view of your operation and how often you or your workers are touching plants, and how often they are waking to and from plant handlings. Also consider the possibilities. There are a lot of growers expanding right now and building brand new greenhouses, but maybe you are not using the space you already have as efficiently as possible and consolidating crops with conveyors would improve this. Instead of building these big, expensive new greenhouses all the time, you might already have enough space.