79 Robyn Shephard – Hybrid Vegetable Seed Pollination


Speaker 1: From the Oregon State University Extension Service, this is Pollination, a podcast that tells the stories of researchers, land managers, and concerned citizens making bold strides to improve the health of pollinators. I'm your host, Dr. Adoni Melopoulos, assistant professor in pollinator health in the Department of Horticulture. When we think about crops that are benefited by insect pollination, we often think about things that grow above ground, like berries, fruits, or nuts. We rarely think about things that are really delicious at this time of year, the things that grow below ground like carrots and turnips, and radishes. While honeybees play a really important role in the creation of the seed for all of those crops in Oregon, as you heard on a previous episode with Garth Mulkey, Oregon is a seed-producing state where we're really good at making seeds. As you may also have picked up in that episode, there's a special relationship between bees and these seed crops, in particular, in producing hybrid varieties of vegetable seeds. To learn more about how these hybrid systems work, I caught up with Robin Shepherd, who's an agronomist with Lakeside Ag Ventures outside of Albany, Oregon.

We met up in a red-radish seed field. In this episode, you're going to hear lots of bees buzzing around, but you'll also hear how these hybrid systems work and how seed growers are making extra efforts to make sure that bees stay healthy while they're pollinating these crops. So grab a radish, lean back, and enjoy the episode. Okay, so we're standing in front of a hybrid-radish field. It's a beautiful field. We were just walking over there and there's lots of bees. Tell us a little bit about how a hybrid-radish system works.

Speaker 2: All right, so a hybrid-radish system. Not in huge detail.

Speaker 1: I was going to say, how do we want to start? Because we could start with a transplanted system or a direct-seeded system. Let's just say, that when it comes to hybrid-radish, you have a male line and a female line, where the male line essentially provides the pollen for the female line. So those cross and then create the variety of radishes that the next grower will take and plant and that'll become the fresh market radish. And it's a process that you could say the planting starts in early in the year, in January or February, and you can get seed in the greenhouse if you're doing a transplanted system in March or with a direct-seeded system that could be planted in, say, April, end of March, April, and starts blooming maybe around

Speaker 2: end of May, which in that case, hybrid-radish, it's a pretty high-maintenance system because you also have to make sure your seed lines are clean. You don't want to have any what we call off types or fertile females or the female line might have pollen, and you don't want that pollen to contaminate what you are going to be harvesting. You just want the pollen from the male system or the male line.

Speaker 1: Okay, so let me just get this straight. So you've got, we're looking at the field there. There's a row of plants that are male plants, and then there's a row of plants that are female plants. And I guess the bees have got to cross it over, and you've got, if I understood correctly, there are these two. Some of these are, you know, sowed in the ground early in the season, and some of them are...

Speaker 2: They're planted in trays in the greenhouse. Okay. And then they come back into the field, or they come to the field, and they transplant the plants into the field.

Speaker 1: So somebody had to put those in the ground.

Speaker 2: Yep, it's a labor-intensive crop. If you're doing it transplanted, especially, you'll have a bunch of people sitting on the back of a tractor, essentially, on a bench, and they'll be throwing plants into the chute, and it gets transplanted through this boot, and it's a labor-intensive crop.

Speaker 1: Okay. So the other thing that you said was contamination and hybrid. I mean, maybe those two terms for some of the listeners are unfamiliar, like, why are you trying to cross these specific plants? Like, what's the point of doing that?

Speaker 2: Sure. Well, it seems like the female line has desirable traits, and the male line has desirable traits. So that's why you'd want to cross them both. Like, For say, the male line, might have more of a rounder shape for that radish bulb, whereas the female, in terms of seed production, might be a really vigorous grower and be able to produce a lot of seed.

So you can get some of those quality traits out of that male and cross it with the female so you can get good quality, quantity seed out of that female.

Speaker 1: Okay. And so, backing up, there's been a lot of decisions made before this field ever came. Oh, yeah. Breeders have been thinking carefully about these crosses. Oh, yeah.

Speaker 2: But that's for sure. We grow a lot of different varieties of radishes, and some of them are preferable for different times of year to grow them. And also, these are varieties that are grown around the world. So say, if production in New Zealand didn't go well, they're going to bring it up here, and we're going to plan for planting a, I don't know, 30 whatever acre field up here to compensate for what might have been poor production in another area.

Yeah. There are a lot of different varieties and different traits that are desirable. I've heard that in Europe, the radish that's desired there is more of a, I believe, more of an orangy reddish color.

Oh. Whereas in Mexico or South America, more desirable is a darker red color. I may have those switched, actually. But anyway, it's just interesting how a certain shade of red could be more desirable in one production area versus another. Okay.

Speaker 1: And so the other thing, just a few feet from us, there are two pallets of honeybees. The honeybees are really important for making these crosses. Tell us a little bit about when these honeybees showed up and the bloom is starting. You've got a lot of pods setting. When are these bees going to take off? Sure.

Speaker 2: So the bees are usually placed when the crop is flowering at plus 10%, which we look at flowering in terms of a bell curve. So you have the females starting to flower, and we look at it in terms of like plus 10%, plus 20%, all the way up to plus 50%, and then it drops down from there and it can drop off pretty quick. So down to negative 40%, negative 30%, and whatnot. So the bees will be in the field all the way through until the end of bloom and we'll take the bees out of the field once the crop's completely done.

We don't want to worry about any contamination with wild radishes in the area, which is a huge issue. Oh. It's just, yeah. Essentially, it's just a weed that most people don't think it's a big deal, but when it comes to red radish production, it's a massive deal. So we're always scouting around the area for this radish weed just to make sure it's taken out so it's not contaminating this high-quality radish seed crop.

Speaker 1: Okay. And so your bees come in about 10% ... Why not bring them in earlier than that? Why? 10%?

Speaker 2: I guess we feel like when at least there's 10% of them, it's just a big deal. 10% bloom out here. At least when you're putting the bees in the field, they know there's flowers out here. I'm gonna stay here. I'm not gonna get put out here when there are no flowers and go search for bloom or pollen somewhere else.

Speaker 1: Okay, okay, got that. All right, so, and then when are they gonna leave? Are they getting ready to go? They seem really happy today.

Speaker 2: Yeah, at least right now. I don't know when it gets hotter if they're gonna be too happy, but this field looks like it's getting towards the end of bloom. So I'd imagine they'll be out here another, maybe another couple of weeks. It kinda depends too on the heat. If it's gonna shut down Bloom, it should be here for a little bit longer.

Speaker 1: How do you know you have a good honeybee colony? How can you tell that these ones look like they've got a lot of traffic at the front entrance?

Speaker 2: That's a good question. I am still in the process of learning more about bees. I'm not even really sure. I'm gonna have to ask you what's the signs of a good, healthy colony. But they do look active to me and they're active in the field and I mean, for my lack of knowledge about bees, I feel like that's a pretty good sign. The bees that are here.

Speaker 1: Yeah, I think oftentimes, and we have a nice OSU publication, just looking at the rate of at a certain temperature. Obviously, when it gets really hot, they'll be really, really hot. They won't be as active, but at a certain temperature, they should be coming out at a hundred bees per. I have to look it up. Okay.

Speaker 2: You can look it up together. I should know that.

Speaker 1: Yeah, well, let's after the show. Okay. Is there anything else about bees and radish seed production that we should know about?

Speaker 2: Well, as we were speaking earlier, radish can be a bit of a sponge when it comes to pesticides. It can get disease rather easily, like white rust and mildew. And so we got to make sure that the fields are sprayed and clean because we want to have good quality seed that's harvested towards the end or even just ensure that there is seed towards the end. And insect pests can be an issue. So trying to keep the fields clean being responsible with our sprays and not being negatively impacting bees is a question that we all have right now and trying to figure out how to work really well with bees. I mean, without bees, we don't have radish. We need bees to make sure that this crop is getting pollinated. So without bees, yeah.

Speaker 1: And I think that we, you know, one thing we were talking about is how valuable this crop is. This is a high-value crop. Damage is really expensive. And especially when you're like getting people to plant them by hand. It's a very, very, you've got a lot of investment tied up in here. So tell us about some of the pest problems and disease problems that you can have during bloom. What are some of the things that people really worry about?

Speaker 2: So during bloom, you could have white rust, which can really affect things. It can just deform the flower development and the pods and basically make it to where if a flowering structure has white rust, you can just guarantee you're not harvesting anything out of that infected area.

Speaker 1: So even if it had been pollinated, that would be lost.

Speaker 2: Oh yeah, it'd be lost for sure. I mean, unless you could maybe get a spray on it, then there's a glimmer of hope. But I don't know, usually when I see white rust is in the field, then I'm like, all right, that's that.

Let's move on. Let's move forward to the next pods and hopefully, those will be healthy. Another disease would be mildew, which can affect the stems. Usually, it doesn't get into the seed. It's just more so on the stems. When the stems have it, it can girdle the stem, which affects the development of the seeds further along the stem, which just doesn't get that translocation that it needs to get that quality development.

And then after that, let's see, in terms of insect pests, you can have flea beetles out here, which are just annoying. They can just really ding the crop a little bit. I mean, I don't feel like it can just destroy the crop, but you just wanna have your crop as healthy as possible. And so, yeah, flea beetles, pod borer weevils, which can affect the actual seed. It just kind of digs into the pods and development is poor.

Speaker 1: I've seen this before on Canola, where you've just got like a pod, it looks okay, but then there's a little exit hole and you look inside, all the seeds have been wrecked.

Speaker 2: Yeah, yeah, just destroys the quality of it. So, yeah, those are probably the biggest things. Aphids can also affect it too, just sucking the life out of the stems. So, good stuff.

Speaker 1: You know, and especially seed growers of Western Oregon have been really progressive in working with the beekeepers to come up with the bee protection protocol. What are some of the things that can be done to control the pests and help the bees?

Speaker 2: This is where your help comes in. I feel like further research of just figuring out, all right, what kind of intervals can we use are the best intervals between sprays, fungicides, insecticides, how can we help ensure that bee health is top notch? How do we ensure that we're actually controlling disease or insect issues? So, just more research, more research, more research.

Speaker 1: And that's something a lot of seed growers and people who do consulting have pointed out is really knowing those intervals better, knowing when, how many days after, or how many hours after something has been used and at what rate will it no longer be active against the bees or really the activity drops off?

Speaker 2: Yep, definitely. You won't, also understand like, if you're spraying a field, how long are bees gonna be out of the field? Or if you're irrigating or bees gonna be out of the field, which can affect the amount of hours or time needed for those plants to be pollinated.

Speaker 1: It's almost like you've got a lot of trade-offs. Like, you know, we've got the sprinkler going on the back there and, you know, the plants need, it's so hot, they need that irrigation, but it's possible that the bees are just not gonna go to those flowers.

Speaker 2: Yeah, I know. Oh, it's always a battle. It's like, which poison do you pick? I don't envy your job. It keeps it interesting, right? I mean, people gotta eat too, so it's job security as well. So, it's fun growing vegetables for seed.

Speaker 1: Well, thanks for taking time in your busy day to tell us a little bit about hybrid radish production.

Speaker 2: Yeah, thanks for coming out. It's been fun.

Speaker 1: Thanks so much for listening. Show notes with information discussed in each episode can be found at pollinationpodcast.oregonstate.edu. We'd also love to hear from you, and there are several ways to connect. For one, you can visit our website to post an episode-specific comment, suggest a future guest or topic, or ask a question that can be featured in a future episode. You can also email us at [email protected]. Finally, you can tweet questions or comments or join our Facebook or Instagram communities. Just look us up at OSU Pollinator Health. If you like the show, consider letting iTunes know by leaving us a review or rating.

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Oregon is one of the biggest vegetable seed producing states in the US. In this episode, we catch up with Robyn Shephard, an agronomist with Lakeside Ag-Ventures, in a red radish seed field to learn how hybrid systems work and the steps vegetable seed growers are taking to keep bees healthy during pollination.

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“In a hybrid system you have a male line and a female line, that cross and create the next variety that a farmer will plant to create something like a fresh market radish.” – Robyn Shephard

Show Notes:

  • The science behind the hybrid radish system
  • Why hybridize these specific radish plants
  • What types of radish are desired around the world
  • The role bees play in this industry
  • What diseases there are that can affect this crop
  • What can be done to control pests and help the bees

“During bloom you can have serious diseases of radish, like white rust, which would result in severe loss in seed yield even if flowers were properly pollinated.” – Robyn Shephard

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