Plants, People, Science

Dr. Kirk Pomper: Journey into the World of Pawpaw Cultivation

• American Society for Horticultural Science (ASHS) • Season 3 • Episode 1

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Dr. Kirk Pomper, a Professor of Horticulture at Kentucky State University, is an expert on the pawpaw. He takes us on a journey through the lush history and remarkable qualities of this native North American fruit. With its unique tropical notes the pawpaw stands out as both a horticultural gem and a culinary curiosity.

Together, we unravel the complexities of cultivating pawpaws, exploring everything from grafting techniques to the challenges of pollination. Learn how these trees rely on less-than-common pollinators like flies and beetles, and the surprising tricks enthusiasts use to attract them. Dr. Pomper shares insights into breeding strategies aimed at overcoming obstacles like disease and perishability, all while striving to enhance yield and fruit quality. It's a fascinating look at how innovation and passion intersect in the world of plant science.

Finally, we glimpse into the future of pawpaw commercialization, as breeders work tirelessly to refine this fruit for broader appeal and distribution. From improving storage methods to refining sweetness and flavor, the path to making pawpaws a household name is filled with excitement and opportunity. As consumer interest in local and exotic foods grows, the pawpaw might just find its place in gardens and kitchens across America. Join us for a lively conversation bridging the past, present, and potential future of this captivating fruit!

To learn more, read the article "Comparison of Grafting and Budding Propagation Techniques for Cultivars of the North American Pawpaw" published in HortTechnology https://doi.org/10.21273/HORTTECH05463-24.

Visit the Kentucky State University Pawpaw Facebook page at https://www.facebook.com/ksu.pawpaw.

View "All ABout Pawpaws" at https://youtu.be/VCU4yktHvik?si=RFXMaS6e8DeQa2tV.

Learn more about the American Society for Horticultural Science (ASHS) at https://ashs.org/.
HortTechnology, HortScience and the Journal of the American Society for Horticultural Science are all open-access and peer-reviewed journals, published by the American Society of Horticultural Science (ASHS). Find them at journals.ashs.org.

Consider becoming an ASHS member at https://ashs.org/page/Becomeamember!

You can also find the official webpage for Plants, People, Science at ashs.org/plantspeoplesciencepodcast, and we encourage you to send us feedback or suggestions at https://ashs.org/webinarpodcastsuggestion.

Podcast transcripts are available at https://plantspeoplescience.buzzsprout.com.

On LinkedIn find Sam Humphrey at linkedin.com/in/samson-humphrey. Curt Rom is at https://www.linkedin.com/in/curt-rom-611085134/. Lena Wilson is at https://www.linkedin.com/in/lena-wilson-2531a5141/.

Thank you for listening!


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Samson Humphrey:

Welcome to Plants People Science, a podcast by the American Society for Horticultural Science where we talk about all things horticulture. I'm your co-host, Samson Humphrey, a PhD student researcher at the University of Tennessee, Knoxville, along with my co-host, Curt Rom. Curt, how are you doing?

Curt Rom:

Hi, Sam, I'm doing real well. Yeah, I'm a university professor of horticulture, really emphasizing pomology, fruit crops, but kind of a generalist here at the University of Arkansas. But I'm doing well. You know, it's the last three weeks of the semester and there's always a lot of excitement with the first three weeks of the semester, and then there's a new level of excitement, bordering on anxiety, with the last three weeks of the semester. But I promise you, professors look forward to the end of the semester every bit as much as the students do. And of course we're in the holiday season just upon us.

Samson Humphrey:

I'm surprised to hear that you're excited for it. Curt Gardener, Curt Rom.

Curt Rom:

Oh well, you know, I should tell you that, since I was talking about my gardens, we haven't had a frost yet. So in my garden, my hostas are still growing, I still have pansies, I have impatiens, I have lantana, and I'm maintaining them, I'm still cultivating them. I have marigolds still growing, I have coreopsis still growing.

Curt Rom:

What's even more exciting, every holiday season I buy poinsettias, then at the end of the holiday season, I kind of prune them back and I kind of spoil them a little bit. I take them, put them in my greenhouse and then, as soon as we get past the first frost, I plant them in my garden. I plant them in what I call outside of the fence garden, which I don't give as much care to, and there's deer pressure. Well, poinsettias are a deer resistant plant and for the first time ever since we've not hit frost, we're at about 230 days, 240 days. My poinsettias in my garden are starting to turn color because of the day length. I've never, ever had that they always have gotten. Usually our first frost is October 10th, so we're a full month late on our frost.

Samson Humphrey:

We're going to have to get a picture of you in front of those plants, like as the as the picture for this for today's episode. That's hilarious.

Curt Rom:

Well, it's fun. Actually, part of the reason I grow them is because they're a fun plant to propagate in my classes, and so I always take cuttings and then we'll propagate them and we'll try a couple different methods of propagation. But they do root pretty easily, especially in various forms of synthetic substrates and media. So it's fun. I have a dozen little six inch poinsettias. Since I don't do that till September, they're only going to be six or eight inches tall and spread. So I have potted poinsettias I'll bring into my office. They're also starting to turn color because of daylight poinsettias I'll bring into my office.

Samson Humphrey:

They're also starting to turn color because of daylight. Oh, that's exciting. I have an exciting gardening news flash for you too, kurt. As you know, I am not a gardener in my personal life, but during my master's I did strawberry research and I had this extra research plant that I totally abused. I didn't water it for two weeks. I like increased the temperature to like 30 degrees and then I decreased the temperature for like two weeks to 18 degrees. I think it was very. It was a cold temperature for this plant that wasn't getting water and should have died. It's it's peers. The other plants did die, but this plant survived all ons and it now has its first flower. So I have, I think, the strongest strawberry plant in the world. I'll keep you updated on how it goes.

Curt Rom:

Yeah, plants are amazingly resilient. You know, talk about plants we probably ought to get into today's content. You know I go to the farmer's market in my family orchard. I used to farmer's market and a couple of weeks ago, starting in about the second week of September, it's a big time at our farmer's market because we have a farmer that sells pawpaws and it's kind of exciting, you know, and so it's going to be fun today to talk about pawpaws.

Samson Humphrey:

Fantastic Curt. Let's give the episode a listen. Good morning, Dr Pomper. Thank you so much for joining us.

Kirk Pomper:

I'm happy to be here.

Samson Humphrey:

Could you please take a second to introduce yourself? What is it that you do?

Kirk Pomper:

So I'm Kirk Pomper. I'm a professor of horticulture here at Kentucky State University, and so I'm conducting research and extension work, mainly in Pawpaw, and I'm also teaching plant science and horticultural classes.

Curt Rom:

Hello, dr Pomper. It's good to see you again. Another pomological colleague and friend, yep, good to see you. So you know, we've known each other a long, long time and in my mind I kind of think of you as the pawpaw scientist. You know you're the pawpaw guy, but you know for our listeners, you know, although I grew up in the South and we live in the South, we know about pawpaws. But let's start with some basics.

Kirk Pomper:

What is a pawpaw? Sure, so a pawpaw, it's a native tree fruit. It's actually the largest native tree fruit in North America and kind of looks like a green potato and when you cut into it when it's ripe, it has somewhere between an orange and a yellow flesh, has a very strong tropical-like aroma and flavor and that's due to its being in the same family, actually, as Soursop and Cherimoya. It's in the Ananasia family. So it's unique in that it's the only temperate member that at least grows all the way up into Kentucky and further north of that family. So people have probably walked by it or driven by it if they've come to this part of the country and they don't even realize it, but it's out there.

Curt Rom:

You know, I see it when I go hiking in the Ozarks. I often see it. It's a native plant here. But what's its natural range biologically? Where does it exist and where has it evolved?

Kirk Pomper:

So the native range for pawpaw right now it's basically as far west as kind of eastern Texas, eastern Nebraska, eastern Iowa and as far north as southern Ontario actually, and I guess as far south as right along Florida, louisiana, toward the coast where there's still some chilling, and so it covers quite a large range of eastern United States. And you know, I guess through the last ice age it probably pushed down into the more southern states and then as the ice receded it kind of came back up and repopulated and it may be there are some other Asimina species that grow in southern Georgia and Florida. Asimina parviflora is one of those. So it may have intergraced a little bit with some of those other ones, but it is truly the only member of that family that has large fruit and flavorful fruit.

Samson Humphrey:

You described how it has these large fruits. How large are these fruits exactly and what do they taste like?

Kirk Pomper:

Sure, we're usually seeing a fruit that's maybe about 100 grams or so At least that's what we're hoping for I mean on a tree and in a cluster. So they'll flower in April here in Kentucky and the same tree will flower over maybe several weeks, and so then you're going to get clusters that ripen in, say, late August and through September, even early October, depending on the variety or where it was originally from, and you'll have a range of fruit sizes, but on average we're looking for something that's over 120 grams. We find a lot of those superior varieties being 250, 300 gram average. And so it's, you know, definitely has a lot of different kind of flavors, just like an apple.

Kirk Pomper:

There's many pawpaw varieties out there that have different flavor profiles and some are better than others. If you ever see a pawpaw in the wild, if you see a very long pawpaw, a long, narrow pawpaw, that probably isn't very good. That probably means it's mostly seed right and not much pulp. But if it's kind of egg-shaped and very round, that usually means there's a higher pulp-to-seed ratio, and that's what we're looking for in our varieties. We're looking for maybe 5% or 6% seed by weight.

Samson Humphrey:

I've also heard that bruised pawpaws are something I should look for. What does it look like when one of these pawpaws is good to eat, aside from being egg-shaped?

Kirk Pomper:

Sure, yeah, basically, when they start to ripen they're softening, and that's the real key. Then you'll start having this aroma of kind of tropical-like aroma. Now they will bruise pretty easily. So it's best if you can go up and actually pick them, just about like a ripe peach right. You'll reach up and it'll just kind of easily pull off the tree, and that's probably the best time. If they're on the ground, if they start just like a pop, like a banana, they will start to over ripen and they'll get kind of brown. And when they bruise they'll also get this kind of brown and you'll start getting caramelization flavors. But then if they're bruised, it'll especially create some off flavors.

Kirk Pomper:

Now there's a real range of flavors out in the wild. You'll find turpentine flavors even in the wild, and that's the genetics of papa. And so then when that over-ripens, that can even be worse than turpentine. Then when that over ripens, that can even be worse than turpentine. So anyways, yeah, it's best to actually harvest off the tree and kind of ripen them up. That's the best thing that you'd want to look for.

Curt Rom:

So you were mentioning its native range and it's been here for quite a time. I'd like to ask a little bit about the pattern of consumption and development of this. I assume that this fruit was a, since it is a fruit that's native here and you said it's our largest fruiting plant, was this a food source for indigenous peoples here and for early settlers during the westward expansion, as they're moving across the Appalachians and over here into the central part of the United States? Was it a pioneer fruit and has it kind of been more domesticated now?

Kirk Pomper:

So if you can kind of give us a little bit of its consumption history, Sure, there's several articles out there and basically what is thought is that Native Americans especially were probably harvesting and bringing the fruit further north as the ice age started to recede and it was a favorite food of Native Americans in the area. So they were definitely eating pawpaw and using the bark of the tree for different things. And there was actually an original paper 1905, by Little, who talked about the great potential of the pawpaw. And in about 1917, there was actually a contest by the American Genetics Association to try and find the best pawpaw, and so they put out a request for folks to send fruit. And people did send fruit and there was, you know, there were some winners and actually in that paper it was quoted with intelligent breeding, you know, pawpaw would become a really large commercial fruit in the United States, but it just didn't happen, and that's mainly because of that perishability factor. They're only really able to kind of maintain a good eating quality for about a week unless they're refrigerated, and so there wasn't a lot of refrigeration.

Kirk Pomper:

Back then Blueberry was a native fruit that was also catching on but didn't require refrigeration, so that kind of came on as the native fruit that folks were wanting to grow. But so that's. You know. Pawpaw has a history. Through the years now it's had a lot of folks just kind of producing the fruit Enthusiasts in the Northern Nut Grower Association and NAFEX and some other organizations that kind of kept alive NAFEX and some other organizations that kind of kept alive. And then around the 1980s someone named Neil Peterson became very interested in breeding pawpaw and some really good varieties came out of that. And then of course at K-State a number of folks have been here, but I've been here since 1998, and we've been breeding pawpaws now too and had some good releases.

Curt Rom:

So it then has been domesticated and there is cultivation now, and can you kind of tell us where it is being cultivated, Sure?

Kirk Pomper:

Sure, yeah, and in fact we have a little better idea now what's really going on, because there's enough people actually growing pawpaw now. That was included in the last 2022 ag census and that was the first time it was included 100 farmers in many states. There's just under 100 farmers in Kentucky commercially growing pawpaw. Ohio is probably the largest. They have 165 growers. North Carolina, indiana, tennessee, west Virginia there's kind of a whole stretch of folks growing pawpaws in those areas, and probably the largest commercial use right now for pawpaw, besides farmer's markets and gourmet markets and organic groceries, is the fermentation industry. A lot of people are making pawpaw wine, pawpaw beer. Of course, here in Kentucky we're the home of bourbon and so there are folks also distilling and making pawpaw brandy and you can buy that at several different distilleries, so that's probably the largest commercial market right now for pawpaw.

Curt Rom:

Oh, thanks, that's pretty interesting. I enjoyed hearing that.

Samson Humphrey:

That's fascinating too. If I were to find a pawpaw farm and visit and walk onto that farm, what would I see around me?

Kirk Pomper:

Sure You'd see something. Visit and walk onto that farm. What would I see around me? Sure You'd see something, you know? If so, there's basically two pop-up production methods kind of going on right now. And one is the classic horticultural orchard system. Right, and we've worked on that quite a bit, and there are folks out there basically we don't. We don't have rootstocks, so these are more kind of traditionally spaced trees, maybe 8 to 10 feet apart, in alleyways maybe 15 to 20 feet across, and so you'll see maybe just lines of trees being planted right now. And then there are some who are trying to grow it in patches in native settings, and so there's folks who found really good patches with pretty good genetics and so they're removing the overhanging trees because it is a native understory tree, even though it can survive really well out in full sun after it's about a year old, and so those folks are trying to coax along those fruit to produce and going out.

Samson Humphrey:

And you see a lot of that kind of wild production in Ohio as a major area. Wow, so you mentioned a year old just now. I assume it takes a lot longer for them to grow big enough to produce fruit. How long does it take, and is anything done to shorten the production cycle?

Kirk Pomper:

We've definitely been interested in trying to find a way to kind of bring on the fruit production faster. And so right now mainly we have grafted trees on rootstock. So that's just seedling rootstock and the grafted trees will actually produce flowers and fruit. Maybe at three years You'll see flowers even maybe at two years, because that's a mature bud, so it's grown out and so it's going to flower and fruit faster. And really when they get to about 10 feet they're going to hold the most fruit, or 10, 15 feet tall. And then we've got seedling trees. A lot of people are trying to grow seedling trees. Of course you don't know what the, just as I say, just like your kids or other things, you know they're never this, they're not quite duplicates, and so in the horticulture world we've got a lot of diversity in the seeds. So folks are planting seedlings, but they don't always get the best quality. You know that tree has to go through a period of juvenility before it'll flower, so that can be maybe even six, seven years before you'll get your first fruit.

Curt Rom:

What's the form of grafting that's typically used on pawpaws?

Kirk Pomper:

We spend quite a bit of time on that. Really, the best methods are either chip budding or whip and tongue. Whip and tongue is mostly used across the nursery industry right now, along with chip budding or whip and tongue. Whip and tongue is mostly used across the nursery industry right now, along with chip budding. The only thing that doesn't really work well with pawpaw is inverted T budding. That failed, actually, but other than that, most other forms of crafting or budding work very well with pawpaw, and there's been a lot of work done with propagation, a lot of interest in propagation, because the trees are very highly sought after and so nurseries are selling out of trees very quickly. Grafted trees usually sell from anywhere from about $25 to $100, depending on the variety each, and so they're very sought after right now. So folks are really interested in trying to graft their own trees if possible.

Curt Rom:

Yeah, correct me if I'm wrong on this, but it was my kind of understanding biologically that pawpaw almost has kind of a dimorphic life cycle, that in the juvenile stage it's a shade-loving plant and then when it passes juvenility, enters its maturity stage, it is a full sun plant. Is that correct? And if that's true, do we skip that shade-requiring stage by grafting mature material?

Kirk Pomper:

So it really only comes down to when the seedlings first germinate, until they reach about a foot and a half, about 18 inches. That's when they really require shade, or they can be in a greenhouse. They're more sensitive to UV light at that time and so after they get to that size, even if they're established in the field, even if they're established in the field, you will be able to graft and not have to shade. Now, that said, they will benefit from tree tubes or tree shelters at the first year, and our experience has also been that if you have maybe some wind protection, if you've got maybe trees nearby or a windbreak, that also benefits the establishment of the trees. At K-State we have no windbreaks. It's a strong wind. As I say, it's like we're selecting for the fittest at this point.

Curt Rom:

Survival of the fittest in the research field? Pretty much, yes, well, but you do, by grafting or budding that mature material, you do increase the precocity of it compared to a seedling.

Kirk Pomper:

Yeah, very much so. Yeah, After you know I've got a little over-release. That's a variety of pop at home and you know it's only about three and a half feet tall and it has flower buds all over it. So yeah, it doesn't. It's really about just a two-year, one-year delay, and they already put out flower buds. You don't necessarily want them to set that fruit then, you want them to keep building the architecture of the tree, but you will have fruit maybe within three to four years with a grafted tree where it's six to seven, with the seedling.

Curt Rom:

Okay, so, following my interest in the biology of it, tell me about the pollination requirements for this. Does it require cross-pollination, is it self-fertile, and what is the pollinator that's needed for pawpaw Sure?

Kirk Pomper:

That's a good question. Actually I've had several graduate students in the last few years trying to look at some of those questions. Trying to look at some of those questions and right now, I guess, going to the self-fertility or whether they are self-compatible first. So I did have a student who made a number of crosses and then we grew out the seedlings, we did DNA fingerprinting to really kind of understand whether some of those fruit and with the seeds inside were actually the result of some selfing or crossing. And we do find maybe 5%, 10% of the fruit on the tree was the result of a self and then the rest are crosses. And so I think, even though we tend to say pawpaw is self-incompatible, and there may be some trees that very much are, you know, and some varieties, but I'd say they're of self-unfruitful they just don't set as many fruit, nearly as many fruit, if they aren't cross-pollinating. So that said, pollen transfer with pollinators, you know they.

Kirk Pomper:

I've worked with papayas, I said almost like 27, 28 years. I've seen bees in the orchard several times. I think they were lost trying to get back to their hives. But honeybees do not pollinate pawpaws, it really comes down to flies and beetles. And I actually had a student over the last two years putting out cages with tanglefoot around the flowers and then around just branches trying to see what insects we gather that are coming and visiting. And you know, basically we're seeing a lot of flies but we're also seeing lady beetles and we're seeing a number of other insects. We do see ants too, so all these could be carrying pollen.

Kirk Pomper:

You know, probably the flies and the lady beetles are the most active of the pollinators probably, and so we think at this point we've got pretty good data that those are the most prevalent pollinators. So there are some other insects too. He has a whole range of insects that he's been studiously taking out of Tanglefoot, off these traps and trying to ID, and so he will have an anesthesis done pretty soon. But basically, you know, we're trying to attract non-bee pollinators, we're attracting flies, and so they do have kind of a meaty, kind of maroon flower kind of reminds you of something that would attract flies and kind of a fetid odor. So you can kind of see where maybe flies would be attracted. And so we always kind of kid about if you don't have a lot of pawpaws, you might want to put out something to attract them and people will honestly put roadkill out in the patches or chicken parts or other things to attract the flies.

Curt Rom:

So that's an interesting intercropping system, yes, but the bottom line is really a commercial pawpaw grower would benefit from a multi-cultivar block, not only to spread production risk, but also to enhance pollination and cropping.

Kirk Pomper:

Absolutely. We recommend at least three varieties and unfortunately I can't really tell you which three are the best to cross right now. I've worked with hazelnut self-incompatibility for a while and that's really well documented. But we've been struggling along, trying to really figure that out in pawpaw yet.

Samson Humphrey:

That's fascinating. What are some of the challenges? You see pawpaw yet. That's fascinating. What are the? What are some of the challenges you see pawpaw growers facing?

Kirk Pomper:

Well, I think I think, like any new crop, especially a perennial crop, you know, people need to be willing to wait to get that first fruit and so, especially with our small, we have a lot of small farmers in Kentucky, about 65,000 farms and about 80% of them are, you know, under 200 acres. Many, many folks we work with are making, you know, 25,000 a year and they just have 10 acres and some of them are really dependent upon that income from a small crop and so come from a small crop and so you know a lot of interest in pawpaw in that way. So yeah, I think that's, you know, the major thrust right now is kind of our small growers but they're not only growing pawpaw, you know, and that's the other thing is try a few trees, understand it, realize it will take maybe five years to really come into production and then on to the in those markets as you build up your understanding of the trees, and that's what we recommend to growers how many cultivars, how many varieties exist of pawpaw?

Samson Humphrey:

you've mentioned some already, but how many are there?

Kirk Pomper:

well, there's, there's many, many and you, and there's probably over 50 right now commercially available, and some of them, as I said, there's several major kind of groups of pawpaws that are out there. Carwin Davis was breeding pawpaw in Michigan a while back, and so there's quite a few releases like Tattoo and Taylor from his program. And then Neil Peterson has some really good varieties that are exceptional, like Shenandoah, susquehanna. His naming system is naming after Native American rivers, and so Tallahatchie, wabash, shenandoah, and then K-State's released three. Now we have KSU Atwood, ksu Benson and then KSU Chappelle, and they're really good varieties. They ripen at slightly different times KSU Benson earlier, ksu Atwood later, ksu Chappelle, kind of in the middle, and so we're going to have two more released next year, and then we are breeding. Right now we have lots of seedlings out there from the result of crosses that we're looking at.

Samson Humphrey:

That's so cool. Is there any differentiation between pawpaws that are meant for eating and pawpaws that are meant for making alcohol, like you mentioned earlier?

Kirk Pomper:

That's a good question, you know. I do think unfortunately poorer quality or poor tasting pawpaws actually that bad flavor comes through sometimes in the wine. You know I had some pawpaw wine that someone had made and I could definitely taste the bitterness right that you sometimes get with wild pawpaws and it came through in the wine. So I think we're going to have to be careful, as we, you know, develop as an industry, to realize that you know, some of the wild selections or wild trees are producing some fruit that really shouldn't probably be used even in processing breeding program.

Curt Rom:

What's your strategy on that? Is it kind of a typical recurrent mass selection, where you're identifying parents with unique characteristics and trying to create offspring that would be selected for those traits that you're interested in? What's your strategy and how do you do your breeding?

Kirk Pomper:

Yeah, that's a good question, and you know we've got several parents that we really are using heavily, and one of them is sunflower and it originally was selected in Kansas. It's a very productive tree. You know very kind of, I would say, mid-sized fruit of a good quality but not the best flavor, but it's very productive. And then another one that we like using is Susco Hannah, which is from Neil Peterson's program, probably the most liked pawpaw in taste tests that we do, just that. It has such a good flavor and unfortunately it's one of the lightest producing varieties that's out there, and so we are using those two in quite a few of our crosses. But there's some others too Chappelle and Atwood we've used and some others. There's some other material too that we are looking at that has less problems with disease. Now we really only have one disease that really is a problem with pom-pom and that's a black spot and it's a phyllosticta organism, and sometimes there's two other fungal organisms that will be together with that, but they have black spots and are chronic spots then on the leaves and they will get black spots on the fruit and then when you have a rainstorm right, the fruit expands, cracks and ruins the fruit. So there are some varieties that are definitely more susceptible to the black spot and then some that are a little more tolerant.

Kirk Pomper:

I had one I really thought was resistant, but over time it started, its resistance broke down. But so that's one thing we're really interested in, also the yield. So that's the main reasons why we're looking at some of those parents. So right now we're just doing direct crosses, we're not doing any kind of back crossing. At this point we're not quite that far along. So we're just looking at progeny and right now some of the best crosses are about year five, and so we're starting to see already some precocity differences. I'm seeing fruit on some of those trees this year. Next year should be a really good year for us to look at some of that material and hopefully it won't be a drought year. I hope it'll be a good, nice rainy year Not too rainy, but that we'll be able to look for yield fruit quality.

Curt Rom:

If I will stick to incidents, so I understand you know yield and quality of course stick to incidence. So, yeah, I understand. Yeah, yield and quality, of course, are always primary characteristics. Are there other characteristics that you would also hope? I mean, it's such a fragile fruit. I would assume that you're probably also evaluating for things that are a little less fragile and from a commercial standpoint, is it good to have the fruit all ripen at once? You know, as a former apple breeder, you know we wanted one harvest apples, right, but in peaches it was a little bit the opposite. You know, for commercial fresh market peaches, you know you wanted to spread that harvest window over seven to 15 days and have multiple pigs. Yeah, what's the strategy? That? The other characteristics that you might be looking at.

Kirk Pomper:

We really haven't seen any concentrated ripening on any material I've been looking at, and so everything is pretty much you know. It's flowering over several weeks and then it's ripening over several weeks and worse than that. You know a cluster right. They'll often come in clusters that one cluster will ripen, fruit will ripen on the same cluster at different times, and so it's you know. It's just a real problem.

Kirk Pomper:

We've tried doing some things to maybe concentrate ripening with ethafon applications. It didn't work very well, so that's a problem. I would love to find a more concentrated ripening, but we haven't seen it. Other things we're looking at yes, we'd like a firm pawpaw that would ship better, and sescohand is probably the firmest pawpaw that we have right now. That's also why we're using that, but it's still not firm enough to really not bruise, and we were talking about bruising earlier. You know, if we're trying to ship at any distance at all and it's soft, you're going to get bruising, you're going to get off flavors, and so we're looking for a firmer pawpaw.

Kirk Pomper:

Another thing would be with a color break. I really like to have a color break, and so right now you'll have pawpaws and some varieties especially. They're green and they're soft and they're ready to be picked. But you're going to, you have to go feel through the tree to figure out if they're actually ripe. So I would love to have a yellow color break. There are some varieties that have a little bit of a yellowing on the skin but it's not real reliable. Like Pia, golden is one that does get a little yellow. But we've also looked and the softness correlation with the color is not real great. You know, it's there a little bit but not great. So I'm always telling people if you see a very yellow pawpaw fruit, let us know, because we'd be very interested in that material.

Kirk Pomper:

So, those are some other things. We also don't want it real sweet. We run around 20 to 25 bricks. We don't want a 27 or 30-brick pawpaw. It's so sweet people will not like it right. So that's also sometimes kind of a cloying, just too sweet of fruit and no aftertaste. Of course that's the other thing. We don't maybe a melon aftertaste, which we have in some, but we don't want a bitter aftertaste in any way.

Curt Rom:

That makes a lot of sense to me and that would lead to increased consumer acceptance etc. Going back to kind of an early part of our conversation, you were saying now the USDA is keeping statistics on it, which means that it's expanding in production. What do you see as the forefront or the next steps for commercialization and expanding of production systems?

Kirk Pomper:

Sure. So you know, I think right now, based on the varieties we have, we definitely have a nice niche commercial market for fresh market pawpaws at farmer's markets and local groceries. If we're going to make that next step to ship, we're going to need different varieties that are firmer, don't bruise as easily. But if we don't have that, the next step would also be processing, and so we've actually spent quite a bit of time on that. Right now and this is similar with cherimoya and some of the other sour sop that you'll find in the tropics we don't really have a good method to remove the skin, and so what we'll do is we're going to end up having people cut the fruit in half, or they'll just kind of rip the fruit in half and they'll squeeze out the pulp and the seed. And then we have a number of different devices that are either mechanized or hand cranked that you know, basically like a saucer or a RoboCoop if you've ever seen something like that which will separate the pulp and the seed very effectively. And so you know, that's kind of our stopping area right now. We can't get the skin off. If I could find a really great food I guess technology person and also find the right variety. If I had a little tougher skin, I think that would actually help me with trying to get that skin off right too.

Kirk Pomper:

Right now the skin is not real thick, it kind of doesn't come off, and if you leave any skin in it will kind of get bitter and it's really not a. It will ruin the pulp, so that's, but that's where we're at right now. I know a lot of'll ruin the pulp, so that's, but that's where we're at right now. I know a lot of people like the pulp and so there's definitely a market out there for processed pulp. And the question is how much faster can we make that right now? Because we do have a lot of people processing pulp right now in smaller quantities or 5,000 pounds, I've heard, and things like that. But if we want to get beyond that, we need to have a little more mechanization.

Curt Rom:

You mentioned you need some technological advances. So along kind of that line, I mean we're both pomologists, we're fruit scientists. What are the really big questions you see out there? Horticultural, the horticulture research questions, scientific questions. That's kind of one part of this question I'm asking you. The other part is is what's the science and the research questions that really have you excited as a scientist?

Kirk Pomper:

Well, you know, I think the major problem that we have across horticulture and maybe all areas of ag right now is labor and aging farmers and growers Right, and so we do need ways to mechanize or or reduce labor in terms of the production or or any step right now, and so I think that's that's something we need to be aware of and thinking about. And so for me, with pawpaw, that's kind of going into trying to maybe do high density systems and trying to trellis more and make the labor probably is highest for harvest in pawpaw right now. So if I can reduce the labor on harvesting, that's going to be a significant step. So I forgot what the second part of your question was. What's?

Curt Rom:

got you excited. I mean, are there physiological questions? You know we're facing incredibly variable weather. What's the response to environment, you know? Are there questions about the primary transport, carbohydrates light response, temperature response, chill. You know what are the questions that just have you like man, I'm ready to go to work tomorrow.

Kirk Pomper:

Well, I think the biggest things are actually trying to understand the pollination mechanisms and then doing some more breeding. I really would like to be able to figure out what, what varieties should be planted with which varieties to be able to optimize pollination. So that's. We're going to keep working on that. I'm also looking at at a controlled atmosphere, storage of pawpaw. That's something that a student working on right now, trying to keep the fruit longer so it can be sold longer. So that's another area of interest. You know, I do think you know, I know that I guess I will say breeders always have all the fun, right?

Curt Rom:

But you're creating new things. I mean, it's very entrepreneurial.

Kirk Pomper:

Right. So that's where a lot of my interest is, too, on what we have out there, what we're going to be seeing in those selections that we've made, and then trying to go through and see if we see some with some of these better characteristics that we think of. So that I really do like a lot. But there's many things about pop-up that I find interesting, and I do think that it's a crop that will continue to grow in this space right now as people care about local foods and want to try new things, because who would have thought people would like kiwis and mangoes as much as they do now? Right, it shows that folks are more accepting of things that they haven't been eating. They're willing to try different things.

Curt Rom:

Well, you know that makes sense. That always makes me remember an oft-quoted quote from Thomas Jefferson that the greatest service which can be rendered to a country is to add a useful plant or crop to its culture, crop to its culture. So, maya can see how that would get you excited to know. I mean, you're really kind of like living the dream of adding a new fruit, a new crop, both to the farm enterprise but also to our plates. It sounds very exciting.

Samson Humphrey:

Yeah, I was going to say the same thing. It sounds like you're doing a lot of really exciting work and that you've been studying this fruit for a couple decades now. You've had a really rich pawpaw career, and so I'm curious. Maybe I'm making a hasty assumption here, but I assume that when you were a little plant science student figuring out what you wanted to do someday, I'm assuming that you didn't see pawpaws in your future. I'm curious as someone who's had such a rich and exciting career. What would you recommend students keep in mind as they emerge?

Kirk Pomper:

Sure. Well, you know I look at my path to where I am and you know I've worked on a lot of different crops. I've worked on everything from orchids to beans, to strawberries, to hazelnuts and pawpaw, and I've been around a lot of other students who are working with a lot of different things. And that's what I always tell my students Make sure you know what you're going to, know your project, but also make sure you know what other students are doing too.

Kirk Pomper:

You cannot accumulate enough knowledge. The more breadth of knowledge you have of all horticulture, that's going to serve you really well down the line, because you never know what path you might take. You may end up all of a sudden with an opportunity to go and work in a totally different crop, and yet you know something about it, or at least you can reason out and do the critical thinking that you need to do, because you have talked to somebody already. So that's why I do tell people to be the sponge. Try to learn as much as you can about the other folks around you, because I was lucky enough to be around a number of different crops and projects too folks growing grapes and hazelnuts when I was a PhD student, and that really helped.

Curt Rom:

Well, and here you are. You are the guy that picked up pawpaws and put them in your basket and have made a career out of that. Well, Dr Pomper, I want to thank you. This was a really enjoyable conversation. I know I learned a lot. I'm sure our listeners learned a lot. Also, thank you for working on pawpaw. You know it's a lot of us work on other crops that are real popular, but if we don't have scientists that are working on these new crops, yeah, we don't live to the challenge that Thomas Jefferson gave us. So thank you for doing that work, Really appreciate it. It was a great conversation. I enjoyed it. What did you think, Samson?

Samson Humphrey:

I love it. I knew nothing, next to nothing, about pawpaw before this conversation and I'm about to go out and find one and maybe multiple. I'll have to try multiple of them and eat them this weekend and let you know what I think, kurt.

Kirk Pomper:

Absolutely.

Curt Rom:

Yeah, we have a pawpaw farmer locally sells at our farmer's market, and actually one of my horticulture classmates. So it's always kind of fun and to me it's one of those crops that it's only at the farmer's market for about three weeks and so people kind of wait for it and, talking to the one or two farmers that sell it, they don't keep them very long because people know it's here today and gone tomorrow. Well, this was lots of fun. I really enjoyed it. Dr Popper, thanks for joining us today. Thank you I really enjoyed it.

Samson Humphrey:

Hey, Kurt, that was a fantastic episode, don't you think?

Curt Rom:

Yeah, I really enjoyed that. You know, I've known Dr Pomper for 30 years or something and I've heard him we were friends through the ASHS and I've heard him speak on elements of his research, but it was fascinating to me to hear about cropping and production.

Samson Humphrey:

Yeah, I had only ever heard of this plant as like just a wild. You know, I took my little botany course the first year of college and I could recognize the plant, like in a forest, but it was always in Florida. It was always very small and wasn't the big crop that it seems to be up a little bit farther north. I was really fascinated to hear how many growers there are for this plant. He was giving numbers like in the hundreds of growers throughout several states growing pawpaw and selling pawpaw. I was really surprised by that.

Curt Rom:

Yeah, and then the fact that it's now a USDA census crop I mean, it's a recognized, legitimate horticultural crop. It's something to pay attention to. And you know, I was also interested in his talking about the work that he does and I was fascinated by the breeding work and the research that supports his breeding work related to pollination, propagation, early cultivation.

Samson Humphrey:

Yeah, so many reasons to be excited and so many avenues for collaboration. He was talking about collaborating with people in different fields. Yeah it seems like a really exciting place to be. To learn more about this topic, visit the Facebook page KSU Pawpaw. That's KSU as in.

Samson Humphrey:

Kentucky State University. Additionally, there will be a Pawpaw conference next September, hosted by Kentucky State University and other science organizations, so keep an eye on the Facebook page for more news. You should also check out Dr Pomper's lecture on YouTube titled All About Pawpaw Growing, harvesting and Eating America's Forgotten Superfruit. He also has recently published a paper titled Comparison of Grafting and Budding Propagation Techniques for Cultivars of the North American Pawpaw. He published this in the journal Hort Technology, which is one of the open source peer-reviewed journals published by the American Society for Horticultural Science. You can reach out to him at kirkpomper at kysuedu and you can follow him on LinkedIn for more information.

Curt Rom:

If this podcast and interview resonates with you, I strongly recommend you renewing your membership or joining the American Society for Horticultural Science. If you'd like more information about the American Society for Horticultural Science in general, you can go to the website ashsorg.

Samson Humphrey:

Thank you, kurt, this has been fantastic.

Curt Rom:

Thank you, samson, I enjoyed it a lot. The ASHS podcast Plants, people and Science is made possible by member dues and volunteerism. Please go to ashsorg to learn more. If you're not already a member of the ASHS, we invite you to join. Ashs is a not-for-profit and your donations are tax-deductible.

Samson Humphrey:

This episode was hosted by Samson Humphrey and Kurt Rome. Special thanks to our audio engineer, andrew Sheldorf, our research specialists Lena Wilson and Andrew Sheldorf, our ASHS support team, sarah Powell and Sally Murphy, and our musician John Clark. Thanks for listening.