The 2021 California Summer Trials, scheduled for June 23-27, mark a few changes with the annual California pilgrimage for growers, brokers and breeders.

To begin, there’s the obvious one: when it’s happening.

Historically, the acronym CAST has stood for the California Spring Trials with the event taking place sometime in the early spring over the course of a week. In 2020, the event just so happened to coincide with the beginning of the ongoing COVID-19 pandemic. As a result, the event did not happen with the various stops across the state shuttered. By virtue of unfortunate timing, CAST 2020 was the first horticulture industry event directly impacted by the pandemic. Each stop canceled its showcase and long-booked plans largely fell by the wayside. Some breeders, however, were able to pivot to digital and host webinars to showcase new varieties, but others were left with no real outlet to market their plants.

The 2021 event is scheduled for June for specific reasons. One is COVID-19 and the hope that the event wouldn’t have to be canceled again due to the virus. At the time of this publication, that appears to be a winning bet. The idea was to, in theory, allow more people to attend during a slower time of the year instead of the peak spring. And, as an added bonus, early summer means a larger diversity of crops — such as perennials and annuals that perform well in the heat — to be spotlighted in a more normal growing climate.

CAST 2021 also sees a different shape to the event with the number of participating breeders dropping. This shift actually began in 2020 when Proven Winners declined to participate, even before COVID-19 was a concern. (Proven Winners announced its decision not to participate in CAST 2020 in July 2019.) Citing declining attendance and a desire to “broaden the pool” of industry members who were able to participate, Proven Winners went digital while still planning to showcase its varieties at other industry events. For 2021, Danziger and Terra Nova Nurseries are among the breeders declining to participate, and it’s unclear if any will re-join the event in the future.

Benary, which is participating in the event, also made changes. Instead of limiting visitors to the official five-day window of CAST 2021, its gardens are open through Aug. 31 to anyone who books a visit ahead of time. The idea here is to not exclude a grower or someone else who maybe can’t make it in June, but could come later on in the summer.

In this preview, you’ll find information on all of the stops, as well as some of the new varieties that will be on display at CAST 2021. And if you’re planning on attending or are just planning to observe from afar, we’d love to hear from you. Drop us a line at cmanning@gie.net. – Chris Manning

Photo courtesy of Hoffman Nursery

Greenhouse Management: Has Hoffman Nursery felt the impact of the plant supply issues coming out of the Texas winter storms?

David Hoffman: Yes. Some of our customers I know are sending material down. And that’s from North Carolina all the way up to New Jersey. I’ve talked to a few people that are sending material down, so I imagine that we will as time goes on. I don’t know if we’ve directly seen anything — honestly, a lot our material has been sold out — but there is, across the industry, a lot of truck loads going from all over down to Texas ... I don’t know if it really changed much of what we do. It just diverts plants to different areas, right? We might see effects down the road. We sell a lot to finished growers and if they switch their production plans based on that pull into Texas, that might affect us. But it’ll probably be more of a ripple effect for us.

GM: How do things like booming business, supply chain adjustments and other changes that have come up in the past year affect you in real time? And is it easy to pivot in real time?

DH: If the stock is out there, we can do it. The big inputs in there are stock and labor and I would say that stock, I’ve heard with seed that it’s a little easier to jump and grow fast with. But in some cases, we are looking at two years to grow plants. It’s not as easy to get young plants that way. Sometimes with tissue culture, they can have the ability to ramp up. But if those plants aren’t initiated, that can be difficult, too. Trying to pivot or ramp up specifically for certain items is not as easy as it might seem or sound ... If you don’t have the resources in labor or even soil or plastics, it’s a problem. A soil supplier told me that they were just having problems getting trucks to deliver material. It’s not even that they don’t have the material.

GM: What is the substitution process like at Hoffman?

DH: I would say that you won’t always have a sub for some of these orders that come in. I think it’s an important point. We may have a selection of species, but they might not be functionally fit or have the right look or whatever the customer is looking for to satisfy their needs. Making sure that they have the right plants so they are successful, so they don’t have to go redo their job or can just provide plants to their customers is what’s most important. And that all comes back to communication both internally or with the customers to make sure they know what’s going on.

Greenhouse Management: Can hemp growers utilize mycorrhizae, and if so, which strains should they be using?

Blair Busenbark: First of all, I think hemp growers have been using mycorrhizae for many years. It is important that hemp growers use endo-mycorrhizae strains because they are endo plants.

Scott Inman: Hemp and other plants in that genus utilize arbuscular mycorrhizal fungi, which are a very generalist mycorrhizae. They colonize over 80% of the world’s plants, and there are roughly 400 identified isolates. One associates with a lot of different plants, but it’s also driven by environment, plant type and soil type, as well as the conditions under which the microbes develop. The plant is the driver of this relationship. It’s a true symbiotic relationship so the plant is the one turning on and off the mycorrhizae. That’s a key component of this association for growers to keep in mind.

GM: What benefits do most hemp plants receive from mycorrhizal fungi?

SI: It depends on the conditions. If you look at the different hemp growing segments and what those growers are doing, the big one is nutrient availability. A lot of nutrients are tied up in the soil and require some level of microbial activity. And it’s also a stress mitigation — it allows the plants to have better access to water and nutrients to help mitigate stress.

BB: I would add that it is important to realize that the stresses the crops can undergo themselves are different. It will experience different stressors whether the crop is grown in Texas or Kentucky or even in New York State. And so, the plant is driving what benefits it is getting from the mycorrhizae, and then you throw on top of that the different production protocols and variables — how they are irrigating, how they are fertigating and all the different varieties — you throw all those variables together and really the overall benefit is that it helps the plant be more successful in a wider variety of situations.

GM: What are some tips for growers in how they can incorporate mycorrhizae into their production system?

BB: When you look at how hemp is produced for the high CBD markets, most of those crops are being started in greenhouses and then transplanted outdoors. All of those crops can have a drench as well as a soil incorporation to add the mycorrhizae, that’s a simple way to do it. And then keep in mind that mycorrhizae only need to be applied once during the production cycle, so if you apply it during propagation it will stay with the plant through transplant, and it will continue to benefit the plant throughout its life cycle.

Greenhouse Management: What factors should growers keep in mind when selecting a water-soluble fertilizer?

IB: Crop specificity is the first one. Experienced growers know that crops like tomatoes, cucumbers or lettuce require different proportions and concentrations of essential plant nutrients to thrive. Photoperiodic crops like chrysanthemums or poinsettias prefer lower levels of nitrogen during flower, where phosphorus and potassium management is critical.

The next factor to focus on would be product purity. Nutrient salts are predominantly mined from the earth. The mineral deposits are then purified and graded. For producers growing edible or medicinal crops, the purity of inputs is critical to ensure hazardous heavy metals are not making their way into the finished product.

And lastly, consistent product performance should be emphasized in the product selection process. None of the above matters if your fertilizers are not mixed, proportioned and manufactured to the highest of standards. This is critical because growers spend considerable time and effort perfecting their nutrient recipes to best support their crops growth and development.

“Experienced growers know that crops like tomatoes, cucumbers or lettuce require different proportions and concentrations of essential plant nutrients to thrive.” -Ian Bateman

GM: How do growers dilute/concentrate water-soluble fertilizers?

IB: Water-soluble fertilizers must first be dissolved in water prior to applying to your crops. There’s two primary methods growers use to prepare a dilute, ready-to-use nutrient solution using water soluble fertilizers.

For growers using reservoirs, start by filling water to the final volume in your reservoir and measure out the appropriate amounts of water-soluble fertilizer. Begin adding fertilizer(s) to your reservoir one at a time, while stirring or agitating the water. For multi-part fertilizers, always add the fertilizer that contains calcium first.

To prepare a concentrated nutrient stock solution for use with fertilizer injectors, start by filling water levels to 80% of the desired volume in your clean stock tank. Always use Reverse Osmosis (RO) or low Total Dissolved Solids (TDS) water. Next, measure out the appropriate amounts of water-soluble fertilizer and add it to the stock tank. Generally, it is best practice to allow for each water-soluble fertilizer to occupy its own stock tank.

It is important that you never combine calcium containing fertilizers with sulfate or phosphate containing fertilizers in the same concentrated stock tank, as precipitation will likely occur. Mix with a paint mixer or paddle style mixer for best results, hot water will greatly speed up the dissolution process.