Episode 5 - What Does it Take to Develop a Pecan Cultivar?

In this episode, Dr. Patrick Conner from the University of Georgia Department of Horticulture takes us inside the UGA Pecan Breeding Program. Dr. Conner discusses pollinating procedures, the breeding process and development of a pecan cultivar. How long does it take to develop a cultivar? How many crosses are made in a year? How are desired pecan traits determined?

The episode closes with a short discussion on the three released pecan varieties under the UGA Pecan Breeding Program.

Transcript

SPEAKER_02 0:09

Whether it's pecan or pecan, we cover it all. Orchard management, growth and development, test management, economics, from extended specialists, scientists, county agents, industry representatives, and growers. Brought to you by the University of Georgia Pecan Team. In a nutshell, the Pecan Podcast. This is episode 5 in a nutshell, the Pecan Podcast. I'm Andrew Sawyer, Area Agent in Southeast Georgia. I'm Lenny Wells, Extension Horticulturist for Pecans at University of Georgia. I'm really glad to be together on this episode. We uh get to be with another one of our team members, Dr. Patrick Connor. He's gonna be with us today as we're gonna talk about cultivars. So, Patrick, we're diving right in. Dr. Connor is through the University Department of Horticulture. Uh, Patrick, can you tell us your role and how long you've been in your position?

SPEAKER_00 1:21

Hi, Andrew. Yeah, I'm a professor in the horticulture department at the University of Georgia, and I'm located on the Tifton campus. And I was hired in 1998, so it's been it's been a while now, 26, 27 years.

SPEAKER_02 1:35

One thing we know, you know, is to get a new cultivar. And we want to talk to you as we go about the process that you take to develop a new cultivar, but to get one, it's not a short period, it takes a while.

SPEAKER_00 1:49

No, it's definitely a long-term process. It was especially frustrating, I guess you'd say, early on, because it was a new program, so we had to start making crosses from scratch. And of course, it takes a long time from a seed to produce nuts in the in the in that tree, seedling tree, and then you have to test them for a long period of time. So it did take a long time to come out. Um started in 1998, and our first release, Avalon, was in let's see 2016, I think, when it came out.

SPEAKER_02 2:28

Yeah, Dr. Connor, where do new cultivars come from? Can you just plant a nut, or has it got to come from the branch of a tree in terms of grafting? How does that work?

SPEAKER_00 2:40

Yeah, it it can't come from a nut once you if you want to have a cultivar be true to type. So pecans are not a uh a plant that comes true to type from seed, they are what is called heterozygous, which means pecan has in most genes two different forms of the gene. And so when you go undergo each new generation, all those genes get reassorted into a new combination in each nut. And so the way I tell people pecans are very genetically very similar to people. People are also very heterozygous. So when you have a son or daughter, that son or daughter will have characteristics of both you and your wife, but they will be different from you or your wife, and they'll be different from each other. No matter how many you have, you won't have any two children which are uh identical to each other. And pecan's the same way. When you plant out a hundred desirable nuts, even if they all had the same pollen parent, each of those nuts will produce a different tree with different characteristics. Some will be big, some will be small, some will have um light color, some will have be darker color, the trees will grow different, they'll have different levels of scab resistance. And so that was the one of the problems when early on in pecan uh culture was that they were planting seedling orchards, and those orchards would produce all different kinds of nuts with different shapes and sizes and quality, and it really wasn't producing a uniform mixture and wasn't as valuable. And then they discovered that you could graft the trees. And so, what you're doing when you're grafting is you're taking a seedling rootstock and you're grafting on a piece of branch from the cultivar that you want to propagate. And so, if you have an orchard of desirable trees, all the trops of the trees will all be desirable and they'll all be genetically the same and have the same characteristics. But the seedling rootstocks are all coming from seed, and so those rootstocks are actually all different from each other within the orchard. And so that's why we are we're grafting. And so, in some ways, in a breeding program, that's advantageous because as soon as we find a selection that we want to use as a new cultivar, we can then clonally propagate it as many trees as we want relatively quickly and have it all be the same. Other plants where they're not grafting, they would maybe have to breed that to be true to type. And so you'd have to go several generations to produce a uniform seed lot that then you could release that would have the characteristics you want. But because we're grafting, we don't have to do that.

SPEAKER_01 5:26

So um a lot of the cult older cultivars that we have, when pecans first started to really kind of become a crop as opposed to just a wild native tree growing out there somewhere. A lot of those early varieties came from just sealing trees that someone found and liked and started to propagate those. And even for a long time, uh that's how new varieties were sort of developed is that that someone would just find a variety with or a tree with characteristics they liked and then propagated that. And now it's much different. So Patrick, can you just explain to folks why this process is so long, exactly kind of how you do it and what what the what the process is basically?

SPEAKER_00 6:14

All right. Uh yeah, so the the start of the process is making the cross. So you will go out. Uh, we just finished up crossing for this year. You'll go out in the spring as the trees get ready to bloom. And of course, they're wind pollinated. So if you want to control both parents, so you get a certain combination of parents to produce the combination of traits you want in your seedling progeny, you have to bag the female flowers before the pollen that's blowing on the wind gets on them. So you'll go out in April, you'll look at the trees when you can just start to see the female flowers, but before they're receptive. We'll get in a tree lift and we'll go up along the tree and we'll bag those clusters with a paper bag that keeps the stray pollen out. Then you'll monitor the tree. Usually you'll be putting on the bags about a week ahead of receptivity. Uh, when you when you monitor the tree and see that it's receptive to pollen, we'll come in, we'll open the bag up, puff some pollen from the male parent that we want to use in onto the female flowers to pollinate them, and then reseal the bag and keep it on until pollination season is done. And then you'll come in and you'll they'll get too hot if you leave the bag on through the summer. So you take the bags off, you put some flagging tape on the chute to mark the cross, and then you'll come back in the fall and collect those nuts from the flag chutes, and you'll have your cross, which has the two parents that you wanted to use. And so we're doing that every year. So you have different crosses every year producing different seedling progenies. You will then take those nuts, and what we're doing now is we will stratify the nuts through the winter, get them ready to plant in the spring. Usually we'll plant them in the greenhouse in the early spring, grow them for a month or two in the greenhouse, and then we'll put them in pots, and we'll grow them in pots for the first year. We do that for two reasons. One, it avoids having to dig them out of the ground and kind of mess up the roots that way. They seem to take off better when we plant from potted trees. And the second thing we like to do is we have them on a pot lot all together. We have the ability to water overhead, and so we'll come in in the summer and we'll go out into our orchards and collect scabbed leaves and nuts from a wide variety of trees. We'll wash off those leaves and nuts to produce a um water that has the candidia from the scab in it, and then we'll take that and we'll spray it onto those seedling trees a couple years and try and get them to scab. And so progenies in which we're primarily breeding for scab resistance, and when we screen them like that, things which have a lot of leaf scab and on those pot of trees, we'll oftentimes not bother planting those seedlings because we we figure they're gonna scab anyway, and there's no sense taking up our orchard space with the tree that's gonna scab. And so it allows us to pull out some of the worst scabbing seedlings before they get out into the orchard. So after we've done that screening and the the following winter, when those seedlings are year-old in the pots, we take them out and we put them in our seedling orchard, which is about 10 feet between trees within the row and 15 feet between the rows. And it's it's giving the trees just enough room to get big enough to flower and produce a few nuts, uh, but allows us to maximize the space we have. And then we pretty much will just grow them there for six to 12 years, and which time they will have started to produce nuts. Now, a a seedling tree has to go through a juvenile period before it'll produce uh nuts, and that's different from a grafted tree. When you plant a grafted tree, you've taken a mature branch which has already been flowering normally, or is close to flowering, and you're grafting it onto a seedling rootstock. And those are usually graph begin to flower in a few years. Uh a seedling tree is actually juvenile and it's actually growing different than a mature tree. So a seedling tree will have a strong, strongly apical dominance, so it'll usually have just a single trunk, it'll want to grow up tall pretty quick, uh, and then will only begin to flower. Usually, about the earliest we've seen something flower from seed has been about six years. It's more common for it to take eight to ten years, and so in those first few years, we usually don't pay much attention to them once they're in the seedling orchard until they begin to fruit. And then when they start fruiting, we'll come in in the fall of the year again in a tree lift because they're usually fruiting fairly high off the ground. And I'll just basically ride the tree lift up and down the seedling rows and looking for trees that have begun to fruit. And we'll record things like how much it's fruiting, you know, what is the productivity of the mother tree, whether it's scabbing, whether you've got a lot of black aphid damage or sooty mold on the tree, just general leaf health from minor diseases because these trees are not sprayed for with fungicides at all. Uh, and then we'll take a 10-nut sample from that tree and bring it into the lab and uh crack it out and get percent kernel and nut size and that kind of data. And so basically, what we're doing in that time period, you're giving the trees anywhere from one to five years to prove that they're worth testing further in a replicated trial orchard. So if you have thousands of seedling trees, you really can only keep just a few of those to put into yield trials because yield trials are space intensive. You've got to um get them grafted out. Usually you'll do five to six trees per selection. Uh, and so you really only want the best ones to put into the yield trials that have a potential of being a new cultivar. And so once we've seen something, we usually don't select it until it's fruited at least three to four years. And usually if they haven't um proved their worth by six years, uh you're you're you're probably done with them. So you can't wait forever for something to look good. Uh, and then once you've seen them for a few years, they're they're big and they're high quality and they have traits you want in a new cultivar. At that point, we usually get some graft wood from it, give it to a nursery to propagate for us, and they'll propagate, you know, somewhere around 50 trees, and we'll take those trees and we'll take some of the trees, we'll go into a replicated trial at our station here with the University of Georgia. Some of them will go into grower trials, and then some will go into scab screening trials where we're not spraying the trees uh in order to see the scab resistance. And then we start following them. And again, you're following them for from that time period, probably at least 10 years, somewhere between 10 and 15 years in that trial period to get an idea of see when you only have one tree and it's crowded in the seedling orchard, you really don't can't tell what the yield potential is there because it's just not in good enough conditions, and we're not coming in and we're not shaking the trees and and measuring actual yield. So when we replicate them into the yield trials, those trees, we take actual tree yield from each tree each year, so we really can see what is the pounds of nuts that they're producing per year. So we're getting that data along with uh what is their size and their percent kernel and their color and all these other traits. Uh, when you give them commercial level care, how do they perform? Uh, and so we follow them in there, and then like I said, you want to see the trees as they get to where they're producing full crops and are semi-mature. Uh, and so we'll do them, you know, at least up to year 10. Uh, and then if they're continuing to look good, we we try to keep measuring yield uh for around 15 years. And at that point, you kind of gotta fish or cut bait in terms of getting that cultivar out there to the growers. Because again, this is just a few locations and a few trees. And so you you you're throwing out the things that are obviously not worthwhile, the ones that look like they have potential, then you need to get out to the growers so they can trial them in their orchards. And because we don't have fully mature trees and we've only looked at a few locations, when we release, we try to make it, you know, so that we're telling growers that these cultivars are released for trial in their orchard. We don't know enough, even with this testing, to really say, yes, you should plant acres and acres of this cultivar. We really need to see it around the state uh in more locations, a little bit older trees before we can feel confident that a grower should make a get into this cultivar in a huge way. And so, but we also don't want to wait 30 years before we release a cultivar. So that's kind of the what we decided to do on the in-between and to get things out there quick enough to be useful, but also let the growers know that you know we haven't seen everything we need to see in this cultivar to fully recommend it. So that's kind of the process we're going through in the breeding program.

SPEAKER_01 15:57

So it's a it's a long, laborious uh process, obviously. So I guess that uh means being a pecan breeder comes with some pretty good job security because it takes so long.

SPEAKER_00 16:10

Yeah, you you have to have patience. I mean, nothing you do in science is ever done because you're always finding new problems. And so breeding's no different, you know, it's it's a process, and as you release one cultivar, you have the next one in the pipeline and and you're making new crosses. So every year you're looking at new things. Uh, and so I find it very enjoyable once once we especially now that we have the pipeline fully operational and that we have everything from new crosses in a year to to first time we've seen things fruit to trialing things in a replicated orchard to actually releasing cultivars. And so that that's kind of a seamless process at this point. And it's if you're a breeder, I mean that's always the enjoyment is to see new things coming in and getting things out to growers and seeing how it's performing in the grower orchards.

SPEAKER_01 17:04

And I guess part of the reason this takes so long is just because I mean you're dealing with a long-lived perennial tree. Uh so it's gonna take a lot longer than it would for, say, corn or something like that.

SPEAKER_00 17:19

Yeah, there's no getting around that you have a tree which has to go through a juvenile period and reach a certain size before it'll fruit the first time, but but it you also have a tree that, you know, cultivars change as they mature in an orchard, and so you can't look at a a seedling which are a small tree which is just beginning to fruit, and assume it's gonna look like that when it gets to be more mature and has a full crop load. Uh um, things can look good as a teenager and then not look good as a mature tree. We've all seen that. And so when you try, I found in Pican that when you try to bypass the the natural length of time that the tree takes, oftentimes you pay a price and you kind of wish you hadn't in the end. And so I I think yes, you you you there's just no getting around to it's a tree and it's gonna take its its time to get to where it needs to go.

SPEAKER_01 18:18

So how many crosses do you think you make a year?

SPEAKER_00 18:22

We make usually from 15 to 20 crosses a year. It depends a little bit on what orchard space we have in the seedling orchard. So if we have a lot of space, we'll make more crosses. If we if we're tight on space, uh we'll make fewer crosses, because that's really the limiting factor right now is those those seedling orchards where we're waiting on them to fruit for the first time. Uh, we only have a certain amount of space there. And so as that gets taken up and we're waiting on things to produce their first nuts, uh, we may scale back the amount of crosses we're doing that year. Uh there is a there is somewhat of a limit because pollination season is relatively short. It's just a couple weeks in the spring, and once it's over, it's over for the year. And so you're up there on a tree lift putting on the bags, you know, and it it takes a good bit of time to to put those on and also to pollinate. And so you you kind of get we're usually out there most of the day, every day, getting those bags on, and so you can only get so many on a year uh in terms of that timing-wise. So it's those are kind of the factors that limit how many we do. But we usually try to do 15 to 20 crosses a year, and we like to get 100 to 150 bags on per cross.

SPEAKER_01 19:42

Okay. And that's and obviously there's gonna be multiple, you know, you're putting them on terminals that have multiple clusters on them. So there's several chances for each one of those, I guess.

SPEAKER_00 19:54

Yeah.

SPEAKER_01 19:55

What percentage of of those that you pollinate uh do you think make it?

SPEAKER_00 20:01

Not as many as we would like. So and it varies a lot by the mother tree. We found over time that the younger the mother tree is, the more nuts per bag you usually get. And so we try to use relatively, you know, trees year six through twelve are usually pretty good. Mother trees, you get a fully mature tree, they get harder to use because you got to get up in the lift farther. Uh, the females are further apart, and they just don't tend to set as many nuts per cluster on the older trees. Cultivar makes a big difference. Obviously, you try to make your cross using the more prolific cultivar as the female parent. So if you were crossing desirable by Elliot, you'd want to use Elliot as the female parent because it tends to have more nuts per cluster than does a desirable, which thins its clusters down. So you kind of got to look at it that way a bit. But timing, you know, influences it too. Sometimes you can't, like Elliot is receptive real early. And if you have a lot of things that are receptive early, you may have to use the other parent as the female just to have the timing work out. But on average, we found that we get over all the trees and crosses about one nut per bag that we put on. And it we'd like it to be higher than that, but they just I think it's the heat in the bags or something. They just don't particularly care to be bagged, or the pollination timing's not just right. It's it's a little bit tricky, and I wish we could get more than we do uh per bag.

SPEAKER_01 21:38

Yeah, that's part of dealing with Mother Nature, I guess. So how do you det how do you select what parents to use and and what traits are you looking for? How do you know which one you want to be the pollen parent, which one is the you want to be the the female flower? Uh can you go through some of that?

SPEAKER_00 21:58

Yeah, so when you're When you're deciding, you know, I'll sit down in early spring each year and kind of decide what my crossing plan is. And it it changes, it's changed over the years in terms of what we've been looking for. But what you're doing in general is trying to find two parents which in combination have the traits you want to produce in your new seedling population. So, for instance, if we have some far northern varieties like Carlson Center and Lucas and Major, which they're ripening in early September, but they have a real small nut size. And some of them, like Carlson Center, are scab susceptible. So you you think, well, I want the early ripening, but I want a larger nut. And so you've got, and I also want it to be disease resistant. And so you've got to find a parent to cross to that, which would then bring in larger nuts and disease resistant, and hopefully also early um harvest. And so you got to kind of look through your germplasm and say, okay, what would be a good parent to cross to Carlson Center to get my nut size up? Well, Pawnee is one that comes to mind because Pawnee is a fairly large nut and it's also early. And so that might get you something which is early and bigger and earlier than pawnee, but pawnee does not have scab resistance. And so you might wind up with scab susceptible seedlings. And so there's there's other ones like we have a gardener by Kansas selection, which is as early as Pawnee now, but is more scab resistant. And so that might be a better parent because you again would have the scab resistance, the size, and the earliness. And so you might use that instead of pawnee. Or you might have to use make one cross with something which is also early and susceptible, and something else which is more resistant but not as early, and and look at both proteins. So you're just trying to fit together the traits you want to produce in your new seedlings. And then there's some there's some practical things that come into it. Like we're doing our crossing on the campus, and so you have to have a tree which is available, at least one of the two, uh, in order to have a mother tree. Uh, you can't cross things that you don't have germplasm of. Um we tend to um when we do our pollen and we dry the pollen down, we can store that in a freezer and use that over multiple years. So we have some of the parents can be pollen stocks that we have in the freezer, but of course the seed parent has to be out in our orchards. And then when you're trying to decide what the mother tree is and what the what the pollen tree would be, you look at a couple different things. Um, like I said earlier, the the more prolific the tree is, the number more nuts per cluster makes a better seed parent. Genetically, for most things, it doesn't matter which is the pollen parent and which is the seed parent. Most most traits are 50-50 from the pollen and the seed parent. And so you're not really looking at it that way. You're more looking at more practical aspects. What do I have the best tree in the orchard of? What is going to produce the most nuts per bag? Uh, and then timing. You know, you can only do so many bags and pollinations per year or per day. And so sometimes you got to switch what's a pollen parent, what's the seed parent, just to get the timing right of when you have labor to um to get to those trees. And then what do you have? I try to use fresh pollen. I think it gives a little better set than frozen pollen. And so uh sometimes I'll give priority to the seed parent to be that thing which has will work best, you know. So if you have a protandus tree where the pollen shed early, uh that would maybe make a better pollen parent. And then something which is protogenous, you might might use as your seed parent. And so getting the timing of the bloom workout also goes into it.

SPEAKER_01 26:11

And so you've got what, probably four or five traits that you're really looking for for your program for for the area you're producing cultivars for.

unknown 26:21

Okay.

SPEAKER_01 26:21

I mean, scat disease resistance is obviously a big one. Uh, what else would you say, at least at this at the current time that you're looking for? Because I know like you said, it changes.

SPEAKER_00 26:32

It's changed over year. Of course, there is another you the breeding program long standing from the USDA. And so we've tried to not redo what they've done, but try to do things which are a little bit different than they've done in the past, uh, to produce things which would be more useful. So I'm mostly focused on the southeastern region in our breeding program. So, of course, scab resistance has always come to the forefront. That was the basis of why this breeding program was created, was because newer cultivars, which had been developed in the central region, were put into our region and had too much scab susceptibility to be useful here. And so we needed to get things which would be adapted to our rainy summers and have higher levels of scab resistance. So that's always been something that we have selected for, and that's the number one thing that we throw out seedling trees for is just being too scab susceptible to, I feel, be global here in our region economically. And so that's been a strong feature of the breeding program throughout. Uh, we've been looking, other traits we look for, we would like to have more large cultivars which are coming off in September, and particularly early September. Things that would match Pawnee but have superior traits to Pawnee in terms of productivity and scab resistance. Uh, and that's been a little bit difficult. Pawnee is really kind of a unique cultivar in terms of coming off in early September and being the size that it is. We've we've got things that are earlier than pawnee, but we don't have things. Well, maybe we have some coming in trial, but it took us a long time to develop things which were as big as Pawnee that were as early as Pawnee. And so that's something we've been looking for for a while now. Uh, when we first started the breeding program, we were looking strongly at having things which were consistent yielding. So when I started, desirable was the big cultivar, and it was the big cultivar because it would produce a crop most years, things which were strongly alternating uh were difficult for the growers because you'd have an on-year with low quality followed by an off-year with low productivity, and a lot of cultivars washed out because of that that that production pattern. And so, but over time the industry has changed, and now we have a lot of growers which are crop load thinning, which helps you manage very productive cultivars like Creek, where hedging, and so it's a little less clear to me that uh the consistent bearing is of the same importance, you know. But we do have growers which do not want to crop thin and do not have the equipment or don't want to start start hedging, and so we're not stopping looking for consistent bearing, but we're also looking for cultivars now which are very productive that maybe would work in a hedging system. So the last five to ten years, we've been looking at trying to find things which maybe have more ability to fruit on interior shoots using things like Creek and Lakota and Western. It's very productive parents, which might fit in well with a hedging system. And when you control the crop load, we're also looking in the last few years at tree size control. Uh, we don't have anything which I would consider a true dwarf, which would be, you know, kind of a super short, stocky plant with short inner nodes. I haven't really seen that, but we're looking for trees which maybe aren't growing as strongly. So we've been crossing with things like Tom and Creek and Cheyenne and some selections that we have from our program, which have smaller trees. Uh, we've noticed that the far northern varieties, things like major and um Carlson Center Lucas, they all tend to have smaller trees. And so we're we're we're crossing those in to see if we can get larger nuts but smaller trees, and hopefully, you know, be able to grow those in a in a denser orchard system and get our productivity and our orchards up using those. So it has changed over the years, but you you kind of every five years you kind of are moving the breeding program forward, and it's what you have is germplasm determines what you can what traits you can go after. And so that as we're we're producing our own selections which have new combinations of traits, then we can add cross them into something else and bring in more traits. And so if you add spent your first generation getting early nuts with scab resistance, and you have those selections, then you can cross it to something which is maybe higher productivity or larger nut size and bring that trait in. And so over time you're just getting more and more favorable combinations of traits, and so your cultivars will look better and better over the years as they come out.

SPEAKER_01 31:41

Yeah, so it's just kind of builds on itself at some point. Yeah, that whole dwarfing trait is something that you know I hear I hear talked about a lot, but I'm just not I'm not convinced that it's really out there. It may be, but but uh you know, the pecans are pretty diverse, uh, and we and we have still have native populations of them out there. So maybe we'll see that one day, but I just feel like if you think about the natural history of the tree itself and where it's a well, you know, it's native habitat, where it's adapted to. I don't know that those conditions really support dwarfism, you know.

SPEAKER_00 32:24

I agree. I think a lot of dwarf trees that were found are trees which the their native range maybe includes uplands and mountains, and up there, you know, you don't have many other trees, and you might want to be smaller so that you're not blown around so much. And if you don't have something shading you out, you can be dwarf and be successful. But pecan, growing up in river bottoms where there's a lot of fertility and a lot of water, a lot of competition. Usually, if you're dwarf in that situation, you're shaded out and you're just not going to be successful in getting a canopy position and and having the next generation of nuts. So you probably have weeded out some dwarf traits. I think longer term it we may be able to develop dwarfness using some gene modification. They're finding a lot of genes now which influence tree size and things like that. And I think over time, as we get into more into gene editing, things like that, there may be some potential to develop smaller trees using those methods versus traditional breeding. But again, that's you know, that's coming down the road. And there's nothing in the pipeline right now, but as I see other tree crops and what they're working on, I it's easy to speculate that that eventually is going to get into pecan as well.

SPEAKER_01 33:46

Yeah, so what do you that brings up a good point? Um, what do you think? You know, the the use of molecular tools and molecular genetics in breeding programs like yours, you know, what do you think that looks like and what do you think the advantages and disadvantages of that are and and how that's gonna contribute going forward?

SPEAKER_00 34:06

Well, when you talk about molecular tools, I guess I would broadly delineate the two different um things. There's one where you're developing genetic markers and genetic tests, and that's that's a situation where you're not doing anything to change the tree genetically, but you're examining the genes within the tree and learning about them. And that's one system of tools, and that's a little further along in Pecan. That's work we're doing here, and we've cooperating with Jennifer Randall and her group in New Mexico, and we've had two large USDA grants that have been working on in this project and getting a genome and getting a sequence of the genomes of pecan, and that's been quite useful. And what you're doing in this situation is you're better understanding what genes trees have and what and may be able to test them for those genes before uh you're getting them out in the orchard. And so, for example, if you were to do this, if you were to find the genetic marker that's associated with, say, scab resistance, right now what we're doing is we're potting the trees and we're spraying them with scab and we're seeing if they if they produce scab and then we're throwing them out. But that's it's sometimes it's difficult. You want to do that usually in June when the trees have young leaves, but some years we don't have much field scab that we can find and we can't get a good spray on. And the last two years we really didn't get a very good screen of our seedlings. And I know we planted out seedlings which will wind up being scab susceptible, and so we've wasted that orchard space on a tree which is not going to be what we want it to be. If we had a genetic marker associated with scab resistance, we could take a small leaf from each of these seedling trees, probably while they're still in the greenhouse. We could run that DNA and look for that DNA marker associated with scab resistance. We could say, okay, this tree has not got that marker, it's not going to be scab resistant, it's not what we want. And we could throw it out within the first couple months and not deal with it. And so, what that is allowing you to do, it's allowing you to grow those trees which have the trait you want, so you're more likely to be successful. And usually what I tell growers is using genetic markers like that, it's like having a fish finder. Instead of going out on the lake and just looking in the best spot and hoping the fish are there. If you have a fish finder, you may be able to see where the fish are. And then you're more likely to be successful, but you still have to go fishing. And so you still have to do all the things you're doing in your breeding program. You're just more likely to be successful. Now, the second broad category of things you can do with genetics in molecular biology is actually change the tree itself genetically. And so that's what you're doing when you're creating Roundup ready crops. You're putting in a gene that makes them resistant to Roundup, so then you can use Roundup on them. There's newer techniques now called gene editing, where you can change specific things within a gene very precisely and create new uh traits. And so I think over time, we're not doing that currently in Pecan. There's it's not out there, but I think it will be in the future because it's getting more and more efficient to do these techniques, and they're getting more and more specific in the changes you can make. And so instead of selecting a new seedling tree that's scab resistant, you may be able to take a tree which is scab susceptible and change it so that it is scab resistant. And so maybe you could produce a desirable tree which is now resistant to scab, whereas before it was susceptible. I think that'll be coming down the road. It's it's going to be a little while, but it's clear to me that's where the science is going. And I think that's I think in the future there'll be a combination. I think you always want to have breeding programs because you're even with gene editing, you're only making a small change, and it's usually fairly complicated and expensive to do that process. And you'll want to take cultivars that exist and make those changes, but you also want to produce new cultivars which have a broader combination of favorable traits. And I think the two two processes will work hand in hand in the future.

SPEAKER_01 38:43

Uh, and so that you'll we'll be doing both to make even more changes in the in the yeah, and of course, you know, all that that step, of course, has to come with buy-in from the pecan industry and people who buy pecans and eat pecans. Yeah, yeah, yeah.

SPEAKER_00 39:07

Yeah, it's too long and expensive to do it. Uh, but the gene editing is a little bit different than the the traditional methods, and that you're not usually adding in additional genes, and so and you're making smaller changes, which and so you can wind up with plant which is only got a very small change at the end. Uh, and so it's there's less regulatory hurdles. I think over time there'll be less, there'll be more buy-in from the public as they see the advantages these crops can bring, both to the grower as well as to the consumer. They've recently released our a blackberry, which is basically seedless. And so instead of having all those those gritty seeds and having the difficulty of using them for things like jelly and things like that, where you have to remove the seed, uh, these would be eat it all. And so I think as we get traits like that, which are consumer-friendly, I think there will be more buy-in in terms of uh of what we see out there in the marketplace.

SPEAKER_02 40:12

Patrick, you've released uh a few varieties so far by three. And you know, you've explained to us a little bit about how they change over time. Can you share your experience with some of that through your releases?

SPEAKER_00 40:29

Yeah, so for starters, we'll talk about Avalon because that was my first release. That cultivar was released in 2016. We trialed that both in our sprayed orchards. And when I say sprayed orchards, our orchards, we tend to manage them so that they're getting a fair amount of scab on things which are susceptible. So we usually only spray, we usually start spraying in June when the rains start and stop in August. So they're getting somewhere between four to six fungicide sprays normally. So within those conditions, usually we'll get very bad scab on something like a desirable, and oftentimes we'll lose the crop, and we'll see scab commonly on things like Sumner and Creek. So when I talk about sprayed orchards, that's that's that's what I'm looking at in our trials. And so we we grafted Avalon into these yield trials and those sprayed orchards, and we also put it in our unsprayed trials uh where we're just looking at to see if we don't put any fungicides on, what level of scab do we get? And so Avalon was a it was a quick grower, it's a very vigorous tree uh in the sprayed trials, and it quickly started yielding very heavily, and it was very consistent year to year, which was what we were looking for in that cross. So the cross was Gloria Grand by Cado. And when we made that cross in um year 2000, when we had looked through the production records of those cultivars, those were two of the cultivars which were the most consistent and high-yielding year to year. And so we made that cross with the idea that we would hopefully get seedling selections out of that, which would be consistent in their cropping. And so when we looked at the mother tree and we we pulled the mother tree out of the progeny because it was not scabbing at all, and and the seedling mother trees are never sprayed with fungicide. Uh, it had a you know, about 47 nuts per pound and somewhere in the low 50s percent kernel, and it looked like a nice kernel. And so that's the reason we decided to pull it out for trialing. And then we put it into the into the yield trials, and it had very good yield. It continued, we never saw scab in the sprayed orchards and in the unsprayed orchards. We'd, you know, maybe you would see a speck of scab on one dot every third year. So it was, you know, virtually clean in those trials as well. And so with the good yield and productivity, the quality was what we were looking for. We decided to go ahead with the release of Avalon and put it out there, and it was picked up very strongly by the growers because it was good quality and not scabbing, and as well as having good productivity. So it met a lot of the needs we had for the growers. It was planted throughout the state fairly quickly in the first five to ten years. Uh, and it was looking good pretty much everywhere in terms of scab. And then I got a call last spring from orchard in northeast Georgia by Augusta where it was showing uh scab. And my hope was at first, you know, was maybe it was the wrong variety, but looking, we did a DNA test as well as looking at the previous year's nuts, and it it is indeed avalon, and it does have scab in that orchard, and so you know and The first question is okay, what's happening in terms of why is it scabbing now when it was not scabbing earlier in all our trials? And what is happening is that scab is not a single organism. Just like there are cultivars of pecan, there are races of pecan scab. And they vary uh in in their genetic makeup. And what is likely happening within this pathogen and tree combination is that you have a large number of resistance genes within the trees, and each of those genes confers resistance to a certain number of races of scab. And so if you have the right combination of resistance genes, you are going to be resistant to most combinations of scab. And that's probably what was happening in Avalon. And so in most orchards we plant it in, you are resistant to those races of scab. However, when you plant something widely throughout the state, you come into contact with more and more different races of scab. And to complicate it even further, we've found that scab likely has a sexual stage. And so there are likely new races of scab being produced all the time within our orchards. And so eventually what happens is you become into contact with a race of scab, which you do not have a resistance gene to match, and then you become susceptible to that race. And that's likely what happened in that orchard up by Augusta. And so now instead of saying it's resistant to everywhere, you know, you can always say it's resistant in most locations. And so then the question is well, where do you go in the future, you know, with that situation? I still think Avalon's a good culture, it's very productive, it has good quality, it's very consistent year to year in its productivity. It is resistant in most locations, and even within that orchard, I suspect that with when it developed scab, it was not that orchard was not being sprayed at all. It seems that after they started produce spraying a few times, they got the scab under control. I'm very interested to see how it looks this year. Uh, with a moderate level of fungicide sprays, you will it be under control? That'll tell us a lot, I think, about where we should go with this cultivar. But it's still more resistant than most things you're able to plant out in the orchard right now. Unfortunately, the situation is that most things which are resistant, it's not going to be yes, you're immune to scab everywhere, or or you're you're terrible. There's all different shades of gray in between. There are things which are like desirable, now susceptible pretty much everywhere, and that probably are too susceptible that you would want not want to plant them anywhere. You have a few things like Elliot, which are resistant nearly everywhere, and then you have everything in between. And so I think Avalon is still on the side of being very good resistance in most locations. Whereas, and so I think it's still a a valuable cultivar. Um, would I plant you know, acres and acres and acres of it? You might want to hold off and see what it does in this orchard, how easy it is to control. But I don't think you should I don't think you should plant any orchard into everything. I think you need the diversity to to keep your risk level manageable within the orchard. And so if you don't have any avalon, I think you maybe would want to plant some avalon. If you planted a whole bunch of avalon, you might want to look at some other cultivars before you get in too heavy in it and see where it goes. And this is part of why when we release cultivars, we release them for trial. We will know more in five to ten years about avalon and scab resistance than we know now, that's for sure. Uh, but it will likely change over time. They all change over time. And you know how how a cultivar can change. And there's just in a breeding program, there's really no way for us to get around this. We can't trial everything everywhere. We can only trial what we can trial with the with the with the resources we have, and then get it out to the growers and say, okay, this is what we know about it. Um, the next step is kind of going to be up to the growers, and then we need to, as growers find these things out, get this information to them so that they can continue to make those decisions in in the most informed manner possible, but with the knowledge that everything changes over time. So that was Avalon. That was our first release. Our second release was Kalos, which came out, I think, in 2020 during COVID. And that was a Sue by Desirable Cross that was trialed at the same time as Avalon. But we took a little bit longer to release it because it did not have the strong release resistance that Avalon had, and had good resistance, but not, you know, never scabbing like Avalon was. Um but it was larger, it was better quality, uh productivity is was close to Avalon, but not quite as good. But it was a better, higher quality nut and larger. And for those reasons, we decided to release it uh when we did. Uh and that one is it's been slower to be picked up by growers. I think because Avalon looked so good, uh, I think there was less interest in in Kalos. Uh, but I I I still think Kalos to me it's as resistant as probably somewhere around Creek or Sumner level resistance, which is which is pretty good for what we have out there. Uh it's not something you plant and not spray, but I think with the level of sprays we put on our orchards uh commonly you would have low levels of scab with kalos. And then our third release was a sister seedling, the kalos, but it was not grafted into the orchards at the same time. So its testing was about five years behind. We put it into the orchards as as grafted trees instead of topwork trees. Uh, it's something that the mother tree was a year or two behind in its first fruiting. And at the time I ranked it lower than kalos because it was a little bit smaller of a nut than kalos. And when kalos was coming out was when the Chinese market was so important and we wanted the very large nut. Currently, now that size is not as important in the market, and so this new variety, which is called golding, it's maybe this the size doesn't matter, and it's still you know around 50 nuts per pound. Uh, but the exciting thing about golding was that its percent kernel is so high. So we're averaging 60% kernel. It's not uncommon to have 64% kernel. I've never seen it lower than about 55 or 54 somewhere in there, so very high percent kernel. It's a pretty nut, reminds me a bit of Zinner in terms of having a bright color. And it's it's been a good producer, and it's scab resistance, it's it's been better than Kalos in the unsprayed trials. And like Kalos, it very seldom do we see much scab on it in the sprayed trials. And so that's that's where we are with our third release. Like I said, I really like the golding just because it is a consistently excellent quality. It shells out nice. It's just it's one of those, one of those nuts you you know, you go into the the barn when the guys are shelling out the samples, you go, wow, what is that? And it that's almost always it's it's it's golding that is the one that draws your eye like that. And I like the fact, you know, it's interesting, it'll be interesting to see over time how golding performs for scab resistance. Because whereas Avalon did not scab in the unsprayed tiles, golding scabs, but it's never bad scab, it's always just yeah, there's scab on there. I don't think it's hurting the quality in this unsprayed trial. It doesn't seem to be getting worse over years. There are some breeders who would tell you that when you're breeding for resistance, that's what you want. You want a cultivar which has a little bit of scab but doesn't ever get bad, so that you know it's it's the resistance might be more durable. You know, it's just it's just slowly getting scab, but it's it's not something. Whereas when you never see scab at all on it, and then it does become scab susceptible. Maybe that's not what you want because then you might see bad scab very quickly. And and then there's other there's other breeders that tell you the opposite. So it like I said, the this will be an interesting to see to see how this compares over time to something like Avalon uh and how the resistance holds up.

SPEAKER_01 53:03

Yeah, that's that's really interesting. Um that whole thing with Avalon brings up the point that we try to drive home to growers is to even for these low input varieties where you're not you know, where you where you've got decent scab resistance, you still need to spray those, you know, a few times. I think mo I think, you know, even the orchard there in Augusta, I think, you know, probably four sprays is enough to probably take care of that problem, at least at the moment, and that may change down the road, as you mentioned, at some point. But most places I think two, three, four sprays on on something like Avalon or Lakota's is is enough. But it's interesting that, you know, kind of what you just mentioned that you know we we may get to a point one day where Golding has better scab resistance than uh than Avalon or something.

SPEAKER_00 53:56

You know Yeah, I agree. I think those the small number of sprays are good insurance for the orchard. And it's also just because a cultivar is bred to be scab resistant doesn't mean that it's resistant to some of the minor diseases that that can come in there in August and and give you like downy spot, things like that can get severe in some years. And so having those those baseline fungicide sprays will also control those minor diseases as well within your orchard.

SPEAKER_01 54:25

Yeah, we've we've seen that uh powdery mildew seems to be the one that that stands out the most, and because we've got that unsprayed orchard there at the ponder farm where we've got a lot of these varieties in that we don't spray at all. And that's you know, we see on a lot of those varieties that have good scab resistance and do fine without fungicide sprays in that in that little trial. Uh, we do see powdery mildew jump on them a lot of years. So there's there's all kinds of things that can jump on them besides scab that that those fungicide sprays do help for.

SPEAKER_02 54:56

I'm attempting to do a low-input fungicide trial for, and we're actually doing it on Excel variety, uh, as of right now, is to look at, you know, a timing of that spray. Uh one treatment is four sprays, which I would assume to be plenty. And then the other two treatments are three sprays just at different times. Try to get it down to something practical. I think this leaves us where we could really take it, like you just said, where we could get on and just go talking about different varieties.

SPEAKER_01 55:29

Yeah, one thing I'd like to come back to in the next one is that uh about having multiple varieties in an orchard and is there an advantage to that related to scab, you know, and how to manage that whole thing. But uh we'll talk about that on the next one.

SPEAKER_00 55:43

I don't know whether I think there's gonna be or not. You know, the trees are so big. Although I, you know, I don't know. I can see it both ways. It's important to know.

SPEAKER_01 55:53

There's a lot that can go into it. Well, you want to, Andrew, you want to close it out?

SPEAKER_02 55:57

Gentlemen, that was a fantastic episode, and I'm gonna close it out here. Thanks for joining. Uh Patrick, you're coming back, so just we'll get it figured out. And thanks again.

SPEAKER_00 56:09

Enjoyed talking with you, and I look forward to coming back.

SPEAKER_02 56:13

Thanks, Patrick. Thank you all for listening. Stay tuned for the next episode. You can get more information on the University of Georgia PCAN blog in a nutshell, the PCAN Podcast.