Ping Yu: Hello everyone, welcome to the Blooms and Beyond podcast, a podcast that uncovers plant

Ping Yu: history, culture, and management through the lens of science.

Ping Yu: I'm your host Ping.

Ping Yu: How's everyone doing today?

Ping Yu: I'm doing great because here I have a well-known researcher and a colleague of mine, Dr. James

Ping Yu: Faust.

Ping Yu: Joining me today to talk about botrytis blight.

Ping Yu: James has years of research experience in floriculture physiology.

Ping Yu: In today's episode, we'll pick his brain on blight control on ornamental crops.

Ping Yu: So I don't want to steal any more thunder from our speaker today.

Ping Yu: Let's just jump right into it.

Ping Yu: Without further ado, here is my conversation with Dr. James Faust.

Ping Yu: I hope you enjoy it.

Ping Yu: Hi, Jim, welcome to the podcast.

Ping Yu: But first, let's start off with the introduction.

Ping Yu: Can you tell our audience a little bit about who you are and what you do?

Jim Faust: I appreciate coming on your podcast today. I look forward to the discussion. Yeah, I've been in

Jim Faust: floriculture my whole career. I graduated from college in the 80s and got a job in the greenhouse

Jim Faust: and just fell in love with that and have never gotten away. So I've been at a few different

Jim Faust: universities and had grower jobs before that. And yeah, it's been a good career so far.

Ping Yu: Yeah, because I remember I met you at one of the AFE, the National Floral Forum meeting

Ping Yu: a couple years ago back then when I was at grad school.

Ping Yu: And I also met your student, Melissa, at the same meeting.

Ping Yu: But what first sparked your interest in horticulture in general?

Ping Yu: Did you grow up as a nature kid or is this something that stumbled into this trajectory?

Jim Faust: Yeah, yeah. I think most people that get into horticulture have had some childhood experience.

Jim Faust: Yeah.

Jim Faust: And I'm the same. My parents always had gardens. My dad had a vegetable garden and

Jim Faust: my mother always had flowers around the house. And she would actually go out in the front yard and

Jim Faust: you know, disbud or deadhead petunias.

Jim Faust: And she would count how many petunias she would deadhead.

Jim Faust: And she was very proud of the fact that, you know, like every day she could go out there

Jim Faust: and take 200 flowers off.

Jim Faust: And yeah, so it was just kind of, I think all my siblings, I'm the only one who actually

Jim Faust: made a living growing plants, but we all have a passion for plants and gardening.

Ping Yu: Yeah, and speaking of the career, a lot of times we just had an episode on the potential or the opportunities in horticulture that never exist.

Ping Yu: People wouldn't think of so many different job opportunities that even exist for horticulture.

Ping Yu: All they think about is just produce plants, but there are so many opportunities.

Ping Yu: hidden job opportunities within horticulture.

Ping Yu: But with all those plants that you have worked with,

Ping Yu: that you have exposed to,

Ping Yu: even with your family lineage with the plants.

Ping Yu: Is there a plant that is your favorite plant?

Jim Faust: Yeah, you know, there's no such thing as a bad plant, but, you know, I have a soft spot for poinsettias.

Jim Faust: You know, it's kind of a very commercial crop that, you know, it's beautiful, but I don't think a lot of people are really passionate about it because it's just kind of this commodity item.

Jim Faust: And yet it's got to be one of the most interesting plants really in the world in the way it has...

Jim Faust: really become domesticated. It has a storyline that is just unlike any other plant. A lot of

Jim Faust: intrigue, you know, a lot of, you know, it really, you know, wasn't an important plant 200 years ago.

Jim Faust: And then, you know, Joel Poinsett brought the plant to the United States and

Jim Faust: And it kind of caught on a little bit, but it wasn't really until the 1900s, early 1900s,

Jim Faust: where it really became a commercial success and became really associated with Christmas.

Jim Faust: And anyway, that journey is fascinating to me.

Jim Faust: I've been working on a book for a number of years, trying to communicate that story.

Jim Faust: It's hard finding time away from my day job to write a book.

Jim Faust: But I'm still hopeful that I can get this done before I retire.

Jim Faust: Because it's just a fantastic story.

Jim Faust: It needs to be told.

Ping Yu: Yeah, yeah.

Ping Yu: And I think to begin with, right now, a lot of people were just thinking about poinsettia

Ping Yu: as those little tiny plants in the container that they were going to go by during or before Christmas.

Ping Yu: But in reality, when it first started, when it first discovered, it was actually a pretty big shrub right in the wild.

Jim Faust: Yeah.

Jim Faust: Yeah, so it's a plant that will get 12, 15 feet tall in its native location in Mexico.

Jim Faust: And so, you know, that was part of the domestication process really through the 1960s and 70s,

Jim Faust: where a lot of breeding really started in the U.S.

Jim Faust: and really took this plant that actually had been a successful cut flower in the early 1900s.

Jim Faust: But it really wasn't a very good plant.

Jim Faust: plant for greenhouse production because it was such a big plant.

Jim Faust: And then, of course, growth regulators came into existence in the 1950s, and so that helped.

Jim Faust: And then breeding helped to create more compact plants that just didn't want to get, you know,

Jim Faust: six feet tall. And so that really allowed it to become a commercial success.

Ping Yu: And I think though people just get so used to poinsettia, seeing them every year, but there's a lot of brilliant work behind the saying that people keep bringing new varieties to the market, even though a normal consumer wouldn't notice the difference.

Ping Yu: But there's a lot of hard work behind the saying that trying to bring new varieties.

Ping Yu: New varieties to the market every year, right?

Ping Yu: Yeah.

Jim Faust: You know, you'd be surprised.

Jim Faust: You know, there's dozens and dozens of commercial varieties available.

Jim Faust: You know, if I just walk into a greenhouse with, you know, 36 different varieties of red, you'd like really...

Jim Faust: can't tell most of them apart.

Jim Faust: It's, you know, the physical appearance of them is not that variable.

Jim Faust: It's more the production traits that are the targets for breeders.

Jim Faust: Because really the consumer has in mind what the plant should look like,

Jim Faust: so you really can't change that very much.

Jim Faust: You can get some different colors, but still,

Jim Faust: you know, if it's not red, it doesn't sell that well.

Jim Faust: We have orange and yellow and green

Jim Faust: poinsettias and they're really pretty cool looking.

Jim Faust: But, you know, that, you know, people are buying these things

Jim Faust: for gifts for a specific holiday.

Jim Faust: And so, you know, if it's not red, it just doesn't sell very well.

Jim Faust: So so the breeders have really emphasized

Jim Faust: production characteristics. So that'd be something like heat tolerance. If a poinsettia variety is

Jim Faust: heat tolerant, then it's much more easily produced in Georgia and South Carolina and Florida. And we

Jim Faust: have varieties that really can't be grown in those states very well because of a lack of heat tolerance.

Jim Faust: So characteristics like that are really what breeders are looking for. So the consumer might not

Jim Faust: I appreciate that there's a lot of different poinsettia varieties out there.

Ping Yu: Yeah.

Ping Yu: Correct me if I'm wrong, but I think it would be the number one cut flower or floral crop in the United States that has been purchased by a consumer.

Ping Yu: If it's not the orchids, it must be those two.

Jim Faust: Yeah.

Jim Faust: It's orchids and poinsettias as potted flowering plants.

Jim Faust: Yeah.

Jim Faust: Yeah.

Jim Faust: And of course, orchids has the advantage in that you can sell those 52 weeks out of the year.

Jim Faust: Poinsettia is really only sold for about four weeks out of the year.

Jim Faust: So that's kind of impressive that you can be the leading product plant with only basically a four to five week market.

Ping Yu: Yeah, yeah, yeah.

Ping Yu: But every time when we mention your name, it has a close, it normally ties close to

Ping Yu: and Botrytis Blight. And that's basically, you have worked on this project specifically for

Ping Yu: Botrytis Blight Control for years. But can you first start by telling us what is Botrytis and

Ping Yu: what is the agent and how did you start the work on this in the first place?

Jim Faust: Sure. Yeah, I do not have a degree in plant pathology. And actually, I've never actually

Jim Faust: taken a plant pathology course in my life. But I think I have an honorary degree by now

Jim Faust: for the work that we've really been doing botrytis work now for eight years. And that

Jim Faust: really started with a discussion with

Jim Faust: So we got involved with Botrytis really eight years ago when I was discussing research topics with the board at the American Floral Endowment.

Jim Faust: And they had identified that Botrytis and thrips were the two main industry issues that the endowment really needed to address with the research program.

Jim Faust: And I'm not a pathologist, but I have a...

Jim Faust: pathologist colleague at Clemson, who's actually a fruit pathologist.

Jim Faust: So he works with peaches and strawberries and with strawberries,

Jim Faust: botrytis is the major or one of the important pathogens.

Jim Faust: And so he was all on board to kind of be the scientific

Jim Faust: leader of the project, and then I would get the work done.

Jim Faust: And so we made a pretty good team and have been really working on

Jim Faust: now botrytis for a number of years, and I think we've made some nice progress.

Ping Yu: Yeah, yeah, botrytis, you're right. And one of the, I think, the biggest host plants for botrytis is the strawberry from the small fruit perspective. And what is the agent of the botrytis? We're both not plant pathologists, but I have been working with plant pathogen scientists.

Ping Yu: a little bit just what you did.

Ping Yu: But then you definitely have more experience on that.

Ping Yu: But can we talk a little bit about the agent and then move towards to some of the basics

Ping Yu: of plant pathology parts such as the disease triangle from that route?

Jim Faust: Sure. So, you know, we think of the disease is gray mold or botrytis blight, but the organism

Jim Faust: that causes the disease is Botrytis cinerea. And it's a ubiquitous pathogen. It produces airborne

Jim Faust: spores that are probably in my office here today and in your office over there. You really can't

Jim Faust: get away from it. It's

Jim Faust: It's omnipresent.

Jim Faust: And so disease management is a challenge.

Jim Faust: And so we think of disease management with any diseases.

Jim Faust: We use the disease triangle as the kind of the model.

Jim Faust: And so there are three things that kind of,

Jim Faust: have to happen simultaneously in order for you to have a disease occur. And that is you,

Jim Faust: one, have to have the pathogen present. And like I mentioned, botrytis is always going to be present.

Jim Faust: It can be, you know, present in higher populations in some greenhouses, but, you know, it's always

Jim Faust: present. So you really can't exclude it. And exclusion is, you know, a means of control for a

Jim Faust: not for Botrytis.

Jim Faust: The second corner of the disease triangle is that you have to have the right environment

Jim Faust: for that spore to germinate and grow.

Jim Faust: And Botrytis requires temp...

Jim Faust: Well, it has a broad array of temperatures that it grows under,

Jim Faust: but ideally around 65 to 70 is the ideal temperature.

Jim Faust: But you'll even have Botrytis becoming a big problem in a box of flowers that's in a 40-degree cooler.

Jim Faust: So it takes longer at cool temperatures for it to grow, but it will grow at all temperatures. But high 60s, low 70s is kind of ideal. And you have to have high humidity and or a period where the leaves stay wet or the tissue stays wet for a long period of time.

Jim Faust: So that's the conducive environment.

Jim Faust: And of course, in a greenhouse, we almost always have high humidity too.

Jim Faust: So, you know, that is what makes it a bit challenging to control because you have the

Jim Faust: disease present, you have the organism present, you have the environment.

Jim Faust: And, you know, it's kind of funny, I talk about this all the time and all of a sudden

Jim Faust: the third part of the triangle.

Jim Faust: Host plant.

Jim Faust: Oh, thank you.

Jim Faust: Oh, my gosh.

Jim Faust: Yep. So you have to have a susceptible host. And, of course, with flowers and greenhouses, almost all flowers are susceptible. So that's a bit of a challenge. So you have a kind of a perfect storm in greenhouse environments. And that's why it's a problem in kind of every greenhouse on every crop, the floriculture crop. So, yeah.

Jim Faust: Yeah.

Jim Faust: Yeah, that's why we never really get away from it.

Jim Faust: And we'll never really solve the problem.

Jim Faust: It's never going to go away.

Jim Faust: It's not like some diseases where eventually you kind of eradicate them.

Jim Faust: It's just always a problem.

Jim Faust: So the challenge you have is really to manage the situation,

Jim Faust: choosing varieties that have a bit more resistance.

Jim Faust: And that is

Jim Faust: you know, it does work, but within every type of flower, there are going to be, you know,

Jim Faust: some really sensitive varieties. Like with roses, you know, the red varieties are pretty good. They're

Jim Faust: not that bad for resistance, but then you get some of the novel colors and then they're really

Jim Faust: weak. And of course, you just can't sell red roses. So you end up having to grow these varieties that

Jim Faust: are a bit weaker. Yeah. So you just really can't avoid having humid conditions in greenhouses. So

Jim Faust: This leads us to some really having to traditionally or conventional approaches to do fungicide application on a preventative schedule.

Jim Faust: And of course, we learned from IPM management that we really don't like to do preventative applications.

Jim Faust: Because you end up with a lot of fungicide being applied.

Jim Faust: And some industries have...

Jim Faust: approach this a little bit differently, like the strawberry industry in the Southeast

Jim Faust: has had a novel approach. They have basically, you can put a weather station into a field,

Jim Faust: and then that weather station measures when the environment is right for the spores to germinate,

Jim Faust: and actually then communicates to the grower electronically that now we're under a period of

Jim Faust: high risk.

Jim Faust: And then the grower can time their applications of fungicides to the actual need rather than

Jim Faust: doing a preventative program.

Jim Faust: Like instead of spraying every week, you actually just spray on when there's actually a high

Jim Faust: risk.

Jim Faust: So that can really reduce the number of applications of fungicides that one uses.

Jim Faust: Again, challenging in the greenhouse is that we're almost always humid.

Jim Faust: It's not like a field situation where if you have three weeks of no rain, then there's

Jim Faust: very little risk.

Jim Faust: And so greenhouse is really more difficult.

Ping Yu: Yeah.

Ping Yu: Yeah.

Ping Yu: Greenhouse basically created a perfect environment for botrytis or any given pathogen in there.

Ping Yu: The humidity is always there.

Ping Yu: And then the environment with the temperature is always there.

Ping Yu: Like you said, the temperature and high humidity in greenhouse,

Ping Yu: almost perfectly serve the bubble for the pest to survive.

Ping Yu: But in terms of the host range, I know Botrytis has a wide host range and roses are very susceptible.

Ping Yu: And can you name some of our flowers or ornamental plants that are pretty susceptible?

Ping Yu: I guess almost all those ornamental flowers or ornamental crops in greenhouse are somewhat susceptible to botrytis.

Ping Yu: Yeah.

Ping Yu: But what is the most susceptible of the plant that you know of?

Jim Faust: Yeah, well, within a plant, even like a rose, which we know is highly susceptible, there's

Jim Faust: different susceptibilities amongst the tissues.

Jim Faust: So like the leaves and the stems don't get botrytis so badly, but the petals are really

Jim Faust: susceptible.

Jim Faust: And where we have trouble in greenhouse production tends to be in the spring, where you have a

Jim Faust: bedding plant type flowers in the greenhouse. And then we have a week or two of cloudy, rainy weather, and it's cool. And so the garden centers aren't selling product, like sales are slow. And then the grower has a lot of flowering plants in the greenhouse that they're having to hold and they can't ship.

Jim Faust: And that's when we tend to have big outbursts in production.

Jim Faust: And again, almost every flower can get botrytis.

Jim Faust: Petunias and pansies would be some of the worst.

Jim Faust: But they can also be, you know, botrytis is also a post-harvest pathogen.

Jim Faust: So as is the case with roses and often with petunias,

Jim Faust: In the greenhouse, you might not see a lot of infection, but then you harvest those, put them in a box or put them on a truck.

Jim Faust: You know, that truck is, you know, on a plants around carts wrapped in saran.

Jim Faust: You deliver them and really over a 24-hour period, all the spores that are there germinate and start to grow.

Jim Faust: And you take those plants off the truck and the flowers are all melted down.

Jim Faust: So, you know, so petunia flower meltdown is what we would call that, you know, can occur pretty dramatically.

Jim Faust: Even though the plants in the greenhouse might look okay, they show up at the garden center and in bad shape.

Ping Yu: Yeah, I think one of the ways that botrytis gets into the plant tissue is through the wound, especially for cut flowers.

Ping Yu: you're already generating the wound for this pathogen to invade the plant.

Ping Yu: So it serves perfectly and makes them easier to get into the plant.

Ping Yu: But in greenhouse itself, before we're not talking about cut flowers here at this moment,

Ping Yu: just in general for the greenhouse productions for ornamental plants,

Ping Yu: how does this pathogen spread in the greenhouse?

Ping Yu: Does it...

Ping Yu: with wind and water splash or any other practices that will help them to spread widely within the greenhouse?

Jim Faust: Yes, spreading is entirely by air movement.

Jim Faust: And so, when tissue starts to die and decay,

Jim Faust: Botrytis can grow on that tissue and then it has a bloom of gray mold, hence the common name or

Jim Faust: pathogen name. And then that mold can produce millions and billions of spores that

Jim Faust: then float around the greenhouse and land on other tissue and germinate. So,

Jim Faust: Sometimes if you have more air movement, you actually can spread the plants, the disease

Jim Faust: more.

Jim Faust: But really the issue is not the air itself.

Jim Faust: It's that you have allowed plants in the greenhouse to get to the point of producing

Jim Faust: spores.

Jim Faust: So this is why sanitation ends up being such a critical aspect of disease management.

Jim Faust: If you don't let debris sitting on the ground or on the floor or wounded plant tissue on the plant itself, if you keep the facility clean, then you'll minimize the number of spores that are being produced in the facility.

Jim Faust: You won't eliminate them, but if you can reduce the amount of inoculum, then you certainly have less disease.

Ping Yu: Yeah. And so does the gray mold serve the first sign of the invasion of the disease? What is the first sign of that? And where should people go detect the early signs before taking any actions?

Jim Faust: Sure. So the first signs are often a small lesion, you know, a small spot that is often beige colored. And regardless of the flower petal color, the spots tend to be beige like.

Jim Faust: And you can scout crops to look for spots where you, on denser plant canopies, especially we hit these cool, wet periods of the year, you can actually have leaves down in the canopy that are rotting on, say, they're wet on the soil surface.

Jim Faust: And so, and you start to...

Jim Faust: disrupt or disturb that canopy and you'll see spores floating around.

Jim Faust: So you can scout the canopy as a source of inoculum or scout the flowers in terms of looking

Jim Faust: for small spots.

Jim Faust: Once those spots start to occur, then they spread and get bigger.

Jim Faust: Botrytis is a necrotroph, meaning it actually devours and kills the cells as it goes along.

Jim Faust: So as it infects tissue, it's basically sucking out the goodies within the plant cells.

Jim Faust: And so as it does that, it kills that cell and goes to the next one.

Jim Faust: So you start out with a small lesion that gets bigger and bigger.

Jim Faust: And then if you have high humidity conditions, you will have sporulation and that lesion will

Jim Faust: put out this bloom of gray spores.

Jim Faust: And, you know, when you get to that point, then you're kind of in trouble.

Ping Yu: Yeah, you know, a lot of times for pest or disease.

Ping Yu: The best strategy is to prevent them from happening so that you don't have to deal with the big issue or the big trouble.

Ping Yu: But it's what happens, then you sometimes if to...

Ping Yu: If it's too late, you have to lose the game by throwing them out and start over.

Jim Faust: Yeah.

Ping Yu: In terms of once people detect the signs and symptoms of the disease, the next thing that they need to do is to take actions for management to manage this pest.

Ping Yu: And you briefly mentioned some of the traditional or the chemicals or chemistry that's basically the go-to tools for a lot of growers to manage disease.

Ping Yu: But you have worked a lot of research on the...

Ping Yu: biorational products to control the disease specifically.

Ping Yu: Can you tell us what is the difference between the traditional chemicals versus biorational products?

Ping Yu: And what are some of the commonly used biorational products for floriculture?

Jim Faust: Yeah. So if we go back, really, the first line of defense is always the environment. So if we can have a drier environment, that is always the best thing we can do. It's just sometimes we can't do that. So then the next line of defense traditionally has been chemical control. And we have chemicals that work.

Jim Faust: or fungicides that work really well against botrytis until botrytis develops resistance

Jim Faust: to those products. So fungicide resistance is a real problem with botrytis because botrytis,

Jim Faust: it's interesting in that it doesn't have a sexual stage. So most organisms,

Jim Faust: you get mutation or changing of the, you get changes in the genetics and the

Jim Faust: when the offspring, when you have genes mixed between two parents, and then you have a unique

Jim Faust: offspring. With botrytis, it doesn't have that sexual reproduction. It just reproduces asexually,

Jim Faust: and the way it then creates genetic uniqueness is by mutating, and it mutates very aggressively

Jim Faust: and continually. And so when you apply a fungicide that has a very specific

Jim Faust: mode of action where it is interrupting one very critical process in like biochemical process within

Jim Faust: the plant you know it can work really well it can keep the botrytis from you know growing but

Jim Faust: one single gene mutation will allow the the fungus to get around that mode of action

Jim Faust: So even if only 1% of the off, like the mutated fungi has that mutation, then, but that mutated form, the successful form, the form that's resistant to the fungicide, will produce the next generation of spores.

Jim Faust: And so with every application of a fungicide, you are selecting for resistance.

Jim Faust: And when we really have a pretty limited number of products that work effectively for botrytis,

Jim Faust: growers have historically just sprayed the same thing again and again.

Jim Faust: And as a result, we have more and more resistance to those products.

Jim Faust: And so again, if you have no resistance, fungicides we have are really, really good.

Jim Faust: The problem is, over time, there's more and more resistance developed.

Jim Faust: So that's where we've been working on bio-rationals as an alternative.

Jim Faust: Really, the goal is not necessarily to not have chemical fungicide application, but to

Jim Faust: reduce the number of applications we're making so that if we can space out our chemical applications

Jim Faust: more, then the chemicals we have will last longer.

Jim Faust: You know, if we just keep rotating the three or four products that work again and again,

Jim Faust: you're going to have resistance.

Jim Faust: So, if we can interrupt those rotations with other products, then you have less resistance

Jim Faust: to deal with.

Jim Faust: So, biorationals is kind of an option.

Jim Faust: And by biorational, it's kind of a vague term.

Jim Faust: It almost means anything that's not a chemical.

Jim Faust: It's a synthetic chemical.

Jim Faust: And so, there's a lot of different products fall under that umbrella.

Jim Faust: people often think of as biological products would be what I would call biocontrol agents.

Jim Faust: Biocontrol agents are where you actually have a living organism that you're applying.

Jim Faust: And so that's like a specific type of biorational, but there's really four or five different,

Jim Faust: and I'll mention each of them. But biocontrol agents are probably the trickiest products to

Jim Faust: use because they actually have to live on the plant tissue to be effective.

Jim Faust: And that can be challenging for multiple reasons.

Jim Faust: One, you may have other chemicals on the plant that potentially kill the organism.

Jim Faust: And so they might not have compatibility with other things you're spraying, or they

Jim Faust: can actually compete against each other in some cases.

Jim Faust: Or in the case of botrytis, you're trying to get

Jim Faust: the biological organism to live on the foliage.

Jim Faust: And a lot of these bio-control agents are really more happy in the soil.

Jim Faust: And so the aerial environment is a much harsher environment.

Jim Faust: And it gets drier, it's hotter, it's sunnier.

Jim Faust: So for the biological control agents to actually

Jim Faust: colonized plant tissue is kind of difficult.

Jim Faust: And so our success with bio control agents is kind of limited.

Jim Faust: It's not to say they don't work.

Jim Faust: They can work, but it's certainly a harder approach.

Jim Faust: Some of the other options would be bio fungicides, where you actually have a

Jim Faust: biologically based compound that is effective against fungal growth.

Jim Faust: And if you apply that, it's kind of just like applying a fungicide.

Jim Faust: It just happens to be a biological based fungicide.

Jim Faust: And so we have examples of that and they do work and don't have to live.

Jim Faust: They're not living organisms.

Jim Faust: They're just compounds.

Jim Faust: They just happen to be basically biologically derived fungicides.

Jim Faust: And so those can work.

Jim Faust: We have some plant extracts and we have essential oils, which are, again, plant derived compounds

Jim Faust: that can be effective essential oils.

Jim Faust: Our challenge has been phytotoxicity, where they can work pretty well, like use things like thyme oil, but they also can be pretty damaging to plant tissue.

Jim Faust: So that's one of the challenges.

Jim Faust: A group of products we call systemic acquired resistance products are SARS.

Jim Faust: And these actually are products that you would apply that then turn on the natural defense mechanisms within the plant.

Jim Faust: And these are tricky to use.

Jim Faust: The thinking is that you don't immediately turn all these defense mechanism genes on immediately, so they can take a little bit of time to work.

Jim Faust: And then there's also a cost.

Jim Faust: Like if a plant is expending energy to turn on these defense mechanism, there's an energy cost to that.

Jim Faust: And so that creates a challenge in that if you keep spraying these induced systemic part

Jim Faust: resistance compounds, then the plant has to keep turning on these mechanisms of defense

Jim Faust: and that's taking some of the energy away from the plant.

Jim Faust: So there's a challenge that they can work on.

Jim Faust: For sure. But management is challenging. There's nothing easier than spraying a chemical. And it's just like insects are the same thing. This gets awfully complicated when we go to bio-based products.

Jim Faust: It's not to say they can't work, but it just is a challenge.

Jim Faust: So the last category being the one that we actually end up have worked on the most,

Jim Faust: and that would be using plant nutrients. And so, you know, we've published a lot of work showing

Jim Faust: calcium is a very important plant nutrient that helps the plant be resistant to botrytis infection.

Jim Faust: And so plants aren't very good at accumulating calcium in the tissues, especially in flower

Jim Faust: petal tissue.

Jim Faust: Calcium levels are really, really low.

Jim Faust: Like they can be only 5% of the value of calcium that you would find in the leaf tissue on the

Jim Faust: same plant, like a petunia that has, you know, 1%.

Jim Faust: calcium in the leaves will only have like 0.05% calcium in the petal.

Jim Faust: So it's really low.

Jim Faust: And so sometimes our only solution for that is to actually spray or dip

Jim Faust: susceptible tissues in the calcium solutions in order to get the calcium where we want it to go.

Jim Faust: So calcium moves in the leaves fairly well because leaves bring a lot of water through them.

Jim Faust: The water gets evaporated or transpired and the calcium is left behind.

Jim Faust: But when you have a really rapidly developing organ like a flower, where it goes from a small bud to open flower in a matter of days,

Jim Faust: and that flower petal tissue doesn't have spores that transpire water through them.

Jim Faust: So you're not pulling a lot of water into that flower petal.

Jim Faust: As a result, calcium concentrations, calcium's not being pulled into that flower very well.

Jim Faust: And in nature, this doesn't seem to be so much of a problem because in nature, the flowers

Jim Faust: are pretty small compared to what we've done in horticultural breeders have bred everything

Jim Faust: to be bigger.

Jim Faust: You know, same thing with things like tomatoes. In nature, tomatoes are really small fruit. And you breed it to be giant and you start to have calcium deficiency issues because you just cannot move enough calcium into that tissue. And so you get blossom end rot.

Jim Faust: And so once you have some necrotic tissue because of this localized calcium deficiency,

Jim Faust: then you give a place for Botrytis to come in and grow.

Jim Faust: And so we have that problem with poinsettias.

Jim Faust: We call it bracted edge burn, and really it's calcium deficiency on the edge of the bract.

Jim Faust: And then you get little necrotic spots, and then the Botrytis comes in and spreads rapidly.

Jim Faust: So, yeah, so the lack of calcium is a challenge. But even on nice green tissue, we have found that if we can enhance the calcium concentration in that tissue, it becomes more resistant to botrytis infection.

Jim Faust: So what we think is...

Jim Faust: What's primarily happening is, you know, calcium is a vital part of cell walls.

Jim Faust: And so as you strengthen those cell walls, what the botrytis is trying to do is send its

Jim Faust: mycelia, like its little arms and legs, or its roots kind of down in through the cells

Jim Faust: And it goes through the cell wall and sucks out the nutrients.

Jim Faust: And if you have a stronger cell wall, then the penetration of the fungus is not as good.

Jim Faust: So you just don't, even if you get a small lesion, it doesn't grow very well because

Jim Faust: the fungus is just not penetrating that stronger cell wall.

Ping Yu: So basically, to a certain extent that the calcium is actually helping build a thicker cell wall

Ping Yu: to serve as a physical barrier for this pathogen to penetrate.

Ping Yu: But are there any other mechanisms that with the calcium that will actually help the disease control?

Ping Yu: Are there any other mechanisms?

Ping Yu: that the calcium can serve besides the physical barrier.

Jim Faust: Yeah, and calcium is thought to be a signaling device of plant stress.

Jim Faust: And so, again, helps turn on defense mechanisms.

Jim Faust: So it's not clear which, you know, there's several potential modes of action for calcium.

Jim Faust: It's really not entirely clear which is the most important.

Jim Faust: And it could be multiple things, too.

Jim Faust: But the key is having more calcium in the plant tissue.

Jim Faust: Yeah.

Ping Yu: Which method of the application for the calcium is the most effective for Botrytis control?

Ping Yu: Because you did so many different trials or research on this.

Ping Yu: Are there any way that you find the most effective and more importantly, cost effective?

Jim Faust: Yeah, so it depends on the crop.

Jim Faust: Like with cut flowers, we can dip the flowers into a calcium solution and that works really

Jim Faust: well.

Jim Faust: And probably the majority of roses that you would buy in the store these days have been

Jim Faust: dipped into a calcium solution before they were exported out of South America.

Jim Faust: So dipping works really well.

Jim Faust: And we've tested sprays on roses and they do work, just not as effective.

Jim Faust: With the crops that a U.S. grower would be producing, you really can't dip a tray of petunias.

Jim Faust: Like you can't pick it up and, right, it just doesn't work.

Jim Faust: So sprays are kind of what we have.

Jim Faust: And so what you see growers do is basically do a weekly spray as a preventative application.

Jim Faust: Then this actually started in the 90s when we had bractage burned with poinsettia.

Jim Faust: The solution was just once you start getting color development on poinsettias, you just

Jim Faust: do a weekly spray of calcium.

Jim Faust: And we've seen that that works pretty well with a lot of the spring crops that we grow.

Jim Faust: And so growers will tank mix calcium products with other sprays so that they're not actually

Jim Faust: doing an additional spray, but they'll be, you know, if you're already spraying a growth

Jim Faust: regulator or a pesticide, you can mix calcium into those spray applications and then try to

Jim Faust: get a weekly application on.

Jim Faust: So the form of calcium that we recommend, probably what we think is the best would be

Jim Faust: calcium chloride.

Jim Faust: You know, you can apply calcium in different forms.

Jim Faust: For example, you do calcium nitrate.

Jim Faust: But we get better control in general with calcium chloride, and it's also quite inexpensive.

Jim Faust: We like to get the calcium up to at least 500 parts per million, and if not, 1,000 parts per million.

Jim Faust: If you're doing a weekly application, 500 is...

Jim Faust: you know, probably okay.

Jim Faust: With calcium chloride applications,

Jim Faust: weekly preventative applications

Jim Faust: really do make sense

Jim Faust: because it's just not

Jim Faust: very expensive to use.

Jim Faust: And you really want it on

Jim Faust: before the risk of botrytis is high.

Jim Faust: I know some growers that

Jim Faust: when they start

Jim Faust: No weak cloudy weather is coming up and risk of botrytis is going to be high.

Jim Faust: Let us make sure that they have preventative applications on the tissue because it, you

Jim Faust: know, calcium is not mobilized in plants very well.

Jim Faust: So it really is like a surface coverage issue.

Jim Faust: So, you know, you need to treat flowers as they're opening up basically to protect them

Jim Faust: well, you know, having sprayed the foliage two weeks before doesn't help you that much.

Jim Faust: So you have to kind of protect the tissue that is most susceptible.

Jim Faust: So that's why just kind of mixing in calcium chloride into a tank mix can work quite well.

Ping Yu: And how many applications do you recommend them doing?

Ping Yu: Because do they start doing, like from the preventative brain perspective, I guess,

Ping Yu: they do the normal scouting for many of the pest and disease that they have for the greenhouse.

Ping Yu: And once they detected any...

Ping Yu: potential symptoms or even before, like you said, they predict the weather is going to change

Ping Yu: and that will increase the likelihood of the disease and they'll start application.

Ping Yu: And throughout the whole process, for instance, like the poinsettia perspective or other

Ping Yu: or petunia, how many applications do they normally do on an average basis that you would recommend?

Jim Faust: Yeah. I mean, I know growers that just spray it every week. I mean, it's just because I did a calculation once and it was like $2 per acre. There's no real cost to the material itself. It's the labor to do it. So if you just mix it in with other products that you're spraying, then that would be the...

Jim Faust: You know, very little additional cost. So why not just add that? So again, you always have to be anytime you tank mix something, there are risks involved. So you do some trials internally. But, you know, for the most part, that has seemed to work pretty well.

Jim Faust: If it was me, if it's a dry time of year,

Jim Faust: you don't need to be using it.

Jim Faust: When I think most growers have a bit of a sense

Jim Faust: when they're hitting a period

Jim Faust: where they're at moderate to high risk,

Jim Faust: they have a lot of flowers in the greenhouse,

Jim Faust: You know, it's cloudy, wet weather coming up, cool weather.

Jim Faust: You're getting condensation forming on the greenhouse and dripping on the plants at night.

Jim Faust: Those sorts of conditions are when it's ripe for botrytis infection.

Jim Faust: And so you need to be prepared, you know, with your fungicide tools lined up,

Jim Faust: but also calcium as one of the tools in your chest.

Ping Yu: And speaking of the coverage that you mentioned, to make it more effective, you have to cover basically the whole plant at the surface.

Ping Yu: Are there any specific spray or mechanism or machine that...

Ping Yu: will help with the coverage.

Ping Yu: When spraying more, they're just misting with the air blast.

Ping Yu: They just do their traditional spray

Ping Yu: and then hoping they're going to cover the whole plant.

Jim Faust: Yeah.

Jim Faust: You know, if you use a high-pressure sprayer that...

Jim Faust: makes very fine particles,

Jim Faust: you're going to get better distribution

Jim Faust: and better coverage.

Jim Faust: So we've even taken like a petunia flower

Jim Faust: and covered half of it up

Jim Faust: and sprayed half with calcium

Jim Faust: and the other half didn't get calcium

Jim Faust: and then uncover it,

Jim Faust: spray it all with spores.

Jim Faust: And you see that the side of the flower

Jim Faust: that received the calcium spray

Jim Faust: doesn't get botrytis, the other side does.

Jim Faust: So it really is a coverage issue. So your spray equipment, you know, doing a very fine spray that is well distributed, that's turbulent and covers the tissues quite well, is going to be better than like just a real heavy spray that runs off.

Ping Yu: Yeah, because I was assuming that once they spray, especially with this disease and the calcium, you probably want them to apply them so that the chemical or the product would reach the backside of the flower or the leaves as well.

Ping Yu: So basically you wanted to cover the whole thing instead of just the surface or the canopy.

Ping Yu: but also the underside of the leaves, the abaxial leaf, right, so that you can have the whole

Ping Yu: plant covered with calcium to prevent it from getting the

Ping Yu: yeah and so what is your what is the next excitement for your research and career

Jim Faust: Well, we've got several projects going on.

Jim Faust: We're actually doing another pathology project that is kind of unique.

Jim Faust: It's mostly aimed at flowers that are in the aster family.

Jim Faust: There's a disease organism called Itersonilia.

Jim Faust: And it is causing some real problems with the cut flower growers of Gerbera daisy and chrysanthemum.

Jim Faust: It also can infect China aster, sunflowers.

Jim Faust: So, there are small spots on the petals.

Jim Faust: that are partly noticeable in the greenhouse, but then you put those flowers into a box and

Jim Faust: ship them and those spots can grow substantially and make the flowers unsellable. So it's an

Jim Faust: interesting organism because there's only ever been like two or three papers ever published on it,

Jim Faust: so we don't know very much about it. So we've been trying to understand what's going on. It's

Jim Faust: of fungi that usually don't cause the plant diseases.

Jim Faust: So it also makes it kind of unique.

Jim Faust: So that's one project we're working on.

Jim Faust: We are working with unrooted cutting suppliers.

Jim Faust: And so these are the growers in Mexico and Central America

Jim Faust: that, you know, ship poinsettia cuttings,

Jim Faust: impatiens, petunia cuttings.

Jim Faust: and trying to build a better package to ship the cuttings in.

Jim Faust: So we have post-harvest related issues with cuttings

Jim Faust: in that there's not a lot of temperature control during shipment.

Jim Faust: And as a consequence, cutting performance can be sometimes poor.

Jim Faust: You can get too cold, you can get too warm, you can get ethylene damage.

Jim Faust: And so the idea is if we can build a box that actually is more breathable so that gases like ethylene can't accumulate and cause problems,

Jim Faust: because we've done some nice work this past semester showing what concentrations of ethylene really start to cause damage

Jim Faust: and how those concentrations are actually pretty common in commercial shipping boxes.

Jim Faust: And so we're trying to see if we can have a build a better box.

Jim Faust: So that's been an active project.

Jim Faust: We also have a project on post harvest of domestically produced cut flowers.

Jim Faust: So this would be species that, you know, US growers that are like,

Jim Faust: especially cut flower growers are producing that are not being produced in the international market.

Jim Faust: So we have been working a lot with

Jim Faust: zinnia and with dahlia,

Jim Faust: trying to improve the post-harvest longevity

Jim Faust: of those crops.

Jim Faust: So dahlia has a really terrible post-harvest.

Jim Faust: Like they can die in two or three days.

Jim Faust: And so that kind of makes it

Jim Faust: only useful for events.

Jim Faust: Like you can't really sell it as a cut flower

Jim Faust: because most of them don't last a week,

Jim Faust: which is kind of what you hope

Jim Faust: a cut flower will last.

Jim Faust: And then zinnias,

Jim Faust: Well, the other thing that happens with the domestic market is most growers are cutting

Jim Faust: and then immediately selling the next day.

Jim Faust: And they're not really storing product for very long.

Jim Faust: And what would be ideal is if we know that we could store flowers for even if it's this

Jim Faust: two, three, four days, then you could cut multiple days in a week and have more flowers available for your farmer's market on the weekend, for example.

Jim Faust: So storage is really useful as long as you still have good vase life.

Jim Faust: And so with zinnia, we're looking at how to store them better because you can't store them at below 50 degrees because you get chilling injury.

Jim Faust: And so what we've learned with zinnia actually has been kind of interesting is that if you actually look on a zinnia flower, if you turn it upside down, you'll notice it actually is green on the underside of the petals.

Jim Faust: Yeah.

Jim Faust: The top side of the petals is yellow or orange or red or something, but the underside is greenish.

Jim Faust: And those petals actually have stomata on the undersides.

Jim Faust: And so I assume the green is chlorophyll and the plants, the petals are actually doing

Jim Faust: some photosynthesis.

Jim Faust: And so what we've been able to show is you can harvest zinnia.

Jim Faust: And if you put them in buckets, like really high density buckets in an office somewhere in the low 60s would be ideal, like an air conditioned office.

Jim Faust: But if you put light on them, like with some cheap LEDs, you can light them.

Jim Faust: The light intensity would be like about 100 foot candles or 20 micromole per square meter per second.

Jim Faust: So it's not real bright.

Jim Faust: So it's very doable.

Jim Faust: But if you put light on those flowers while you're storing them, they actually still have a very good vase life.

Jim Faust: if you store them in the dark, they don't store well at all. Like you really, the vase life goes

Jim Faust: quite badly. But if you store them in light, they actually seem to continue to, I'm guessing,

Jim Faust: produce sugars and photosynthesize because they're doing photosynthesis. So they still manage to

Jim Faust: produce some food to survive. And so you can have a bucket, like a five-gallon bucket stuffed full of

Jim Faust: flowers and you don't really need the leaves per se because there aren't many leaves on them and you

Jim Faust: can't see the leaves in a bucket anyway it's just the flowers that are exposed to the light but those

Jim Faust: lights those flowers seem to be doing sufficient levels of photosynthesis to you know improve their

Jim Faust: their vase life. So that's been really cool.

Ping Yu: I want to thank James for taking time out of his busy schedule to talk with us today.

Ping Yu: And I have put all those resources and links in the show notes so that you can find more information.

Ping Yu: on all the work that he did.

Ping Yu: Besides that, I've also added the additional resources that AFE provides

Ping Yu: through the AFE Thrips and Botrytis Research Library.

Ping Yu: You can find more information on Thrips and Botrytis

Ping Yu: research control and other resources.

Ping Yu: So that I will add all those links through the show notes so you can

Ping Yu: find all the information and resources on this topic.

Ping Yu: This episode in our first season is made possible through an educational grant

Ping Yu: from the American Floral Endowment.

Ping Yu: whose research priorities helped shape the topics that are featured.

Ping Yu: To learn more about AFE and access their research and educational resources,

Ping Yu: visit their website at endowment.org.

Ping Yu: Conversation like this only happens when you support the show.

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Ping Yu: Thank you for listening. Till the next time, stay healthy and go plants.