Amai is a highly productive indeterminate grape tomato that performs very well in the early and main season slots. It offers medium-tall and vigorous plants with good leaf cover and maintains good fruit size and shape uniformity throughout the production cycle. The fruit are high quality with a rich, deep red color and good flavor. Amai can be used for both indoor and outdoor production, and is Good Seed and Plant Practices (GSPP) certified.
In May 2018, the Horticultural Research Institute (HRI) announced that it was going to invest more time and resources into Plasmopara obducens — the causal agent for impatiens downy mildew (IDM). According to HRI, IDM’s spread has caused a decline in sales of impatiens; the USDA’s National Agricultural Statistics Service estimates that impatiens sales dropped from more than $266 million in 2009 to just under $215 million in 2014.
As a result, a team of researchers is looking further into IDM and how growers can best treat it. Some, like Margery Daughtrey from Cornell University and Dr. Mary Hausbeck from Michigan State University, are researching which products best treat IDM. Others, such as Dr. Cristi Palmer from Rutgers University and Dr. Catalina Salgado-Salazar from the USDA, are looking into the disease’s history to determine what makes it such a problem. And others, such as Dr. Nina Shishkoff from the USDA, are working to better understand IDM’s life cycle.
The history of IDM
Plasmopara obducens was first reported in the United States in the 1880s when it was spotted on a native impatiens called orange jewelweed. Impatiens walleriana, the most common host of IDM and considered to be the most susceptible of the roughly 1,300 impatiens species, was introduced to the U.S. in the 1960s, according to HRI.
But IDM was not a significant issue for the green industry until 2004 when widespread infections were reported in multiple states for the first time, says Dr. Jill Calabro, the research and science programs director at HRI. It’s also unclear exactly why it took more than a century for the disease to wreak havoc on impatiens in production.
“It quickly grew from a minor problem,” Calabro says. “There are reports of businesses going out of business because of this one disease. And that all happened within a decade. That’s an extremely quick shift.”
While Calabro says the answer is still unclear, there is one cause researchers are exploring.
“One theory is that there was a population shift among the pathogen, Plasmopara obducens,” Calabro says. “There is one team of researchers right now [working on this project] that is able to go in and compare the genetic population of modern times — genetic isolates from now — to isolates from the late 1800s. It’s a powerful molecular technique that can provide a lot of information. They are still working through this, but early indicators seem to indicate that the populations are very distinct.”
How to spot IDM and how it spreads
According Calabro, IDM has defining characteristics that are telltale signs a plant has been infected. Growers, Calabro says, should also understand that once a plant is infected, it’s going to die.
“Impatiens downy mildew starts as really slightly chlorotic leaves,” she says. “There might be a bit of stippling associated with it, but it quickly advances and leaves quickly become yellow and then they’ll eventually fall off. There will be a dramatic leaf drop. IDM will kill the whole plant, but first you’ll start seeing these yellow leaves, the leaves will drop, it will kill the flowers and basically it will leave nothing but these stems — sad, little sticks of impatiens — sticking out of the ground devoid of flowers and stems.”
Calabro adds that, in some cases, a white powdery substance will appear on the undersides of the leaves.
“That doesn’t always happen with [IDM], unfortunately, but if you see the white downy on the underside of leaves, that’s a pretty good indication that you’ve got impatiens downy mildew,” she says. “It’s very much dependent on the environmental conditions.”
IDM spreads across the greenhouse in a number of ways, including wind, rain splash and irrigation splash. Cool, wet conditions are also the most common characteristics that allow downy mildew to appear.
“Shaded areas tend to be hot spots, just because they stay wet for long periods of times,” Calabro says.
Growers should also be aware of two types of IDM spores. On the underside of leaves are the short-lived spores that will not survive the winter. But there are long-term resistant spores that are formed in infected plant material — meaning they cannot be spotted. Once they infect a plant, and kill it, the spores are released into the soil.
“Those spores can last years,” Calabro says. “One of the unknowns right now is how long these spores can survive, but it’s thought that it could be as long as five to 10 years.”
What the research hopes to accomplish
Since 2004, impatiens has gone from being the No. 1 bedding crop in annual sales to No. 3 because of IDM, moving it behind petunias and geraniums. According to Calabro, IDM research matters because impatiens are still a major crop in the green industry, with growers, landscapers and homeowners looking for a solution.
“Impatiens is a very important crop in our world,” Calabro says. “But it has kind of fallen since the rise of impatiens downy mildew.”
Researchers face a few different difficulties. With the estimated 1,300 varieties, there are species like Impatiens walleriana that are highly susceptible to IDM and others (like New Guinea impatiens) that are not entirely resistant, but more resistant. The hope is also that new products can be found to replace some of the fungicides that IDM is becoming resistant to. Calabro also hopes that the inoculate point of the disease can be found, as no one is currently sure how exactly IDM gets started each year.
“That’s a long list [of topics] and there are probably more,” Calabro says.
2018 marks our second year recognizing incredible industry leaders through our Horticultural Industry Leadership Awards (HILA), which has become one of my favorite projects of the year. After whittling down the nominees to six outstanding greenhouse and nursery growers, we sit down with the winners to learn how they rose to their leadership positions, and who inspired them along the way.
One of the commonalities among the greenhouse winners this year was having one or two mentors or a specific person who came into the HILA winners’ lives and motivated them to go into horticulture. And, interestingly, all three of these winners said that they had originally anticipated moving into a different field — fashion, photography or even professional golf. That is, until that person came along and helped them to realize that they belonged in horticulture.
It got me thinking about how much difference one person can make, whether they intend to or not, and how simply sharing a love of plants can impact someone’s life. Some of you may remember my column last July, when I was thrilled to have inspired my tenant to create her own little garden, and happy to support her new hobby. While I certainly am not claiming to be a mentor or of a similar caliber to the horticulture industry greats our HILA winners mentioned, I am excited to have been a part of what sparked her inner green thumb. She’ll be moving to her newly purchased home soon, and is already telling everyone that she’s going to have “the best-looking yard on the street.” I shared some annuals, perennials and shrubs to get her started, and she tends to them with great care as she prepares to move, even going out in the middle of a late-night storm to check on them.
Perhaps one day, she’ll have the same opportunity to share her love of plants with someone and inspire the next gardener in the neighborhood. All it takes is one person to make the difference.
And if you’re looking for some inspiration, don’t forget to read the profiles of our HILA winners at greenhousemag.com — I guarantee you won’t be able to read their stories without stopping to reminisce about your own path into horticulture.
Three years ago, Leo Berbee’s Bulb Co. in Marysville, Ohio created Berbee’s Best, an online retail store. Berbee’s Best now accounts for roughly five percent of the business.
Below, Mattie Berbee, the company’s marketing and outreach director, answers questions about Berbee’s Best.
Greenhouse Management: Why did Berbee decide to open an online store, and how did the company go about setting it up?
Mattie Berbee: We obviously knew that moving forward, online is going to be more prominent in the way that people shop. We get a lot of calls [to] our wholesale [division] asking to buy things, from homeowners that maybe had heard of us through talking to other people that know of the product. And while we will always accommodate, we were not in the business at the time to sell to homeowners — we’re a wholesale business. So, with that we asked, ‘How can we make this easier?‘ Instead of turning people away or sending them to their local garden center that may be a customer that sells our products, we figured why not try to take a part of the market for ourselves? This fall will be our third official season [selling online].
GM: What were some of the challenges in developing this part of your business?
MB: The challenge has been saturating the market. We knew we had some demand for [our products] because of the calls we would get or even people that shop in our garden center that say, ‘I want to send this to my grandma who lives out of town.’ We were able to accommodate those requests, but it’s now about, ‘How are we going to make this a thriving business and not just something to accommodate a few requests that we get?’ I would say [that] has been the biggest challenge [and also] learning how to reach a broader audience without spending all of our money on marketing.
GM: Is it a challenge for Berbee to ship online orders at reasonable prices?
MB: It’s not a money maker. We are losing out on some orders because we tried really to stick with these flat rate options. We based the shipping on the quantity ordered or the dollar amount that was solely based on just pulling people in. Myself included, anytime people shop online nowadays, they wait for the free shipping deal, whether it be spending so much and get free shipping or flat rate, $5 shipping. We tried to stick with that flat rate model and knowing that shipping something to California from Ohio is probably going to cost a little more than shipping something straight in Ohio. But at the same time we had, we knew we were going to lose a little on some and gain a little on the other [end].
This interview was edited for style and clarity. Editor’s note: To listen to the full interview, list to the Hort Report podcast here