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. Today's episode is in protecting pollinators and urban landscapes and I'm so excited that we were able to get Dr. Dave Smitley from Michigan State University. Dr. Smitley has worked closely with the turfgrass, nursery, and floriculture industries on developing ways of dealing with emerging pest problems including things like gypsy moth and Japanese beetle.
But a couple years ago, he started to turn his attention to working with the greenhouse and nursery industry to develop strategies and tactics for growing annuals, perennials, trees, and shrubs in ways that's safe around pollinators. The conversation is really wonderful. We cover a lot of real specific practical things.
Also some national initiatives to protecting pollinators and urban landscapes including a conference that's going to be taking place in October in Michigan, specifically on protecting pollinators and urban landscapes. There's a lot in this podcast. I hope you enjoy it as much as I did. Here's Dr. Dave Smitley. It's my real pleasure to have Dave Smitley here from Michigan State University. Welcome Dave to Pollination. Thanks, Anthony.
I'm glad to be here. Out here in Oregon, as you're aware, pollinators and horticultures are a big issue. But there are really not that many resources out there for how to effectively manage pests in horticulture industries that minimizes impacts to pollinators. I was really excited to discover your work and those of your colleagues. How did you find yourself addressing this challenge?
Speaker 2: Well about three years ago, it really hit the national news about the neonicotinoids and their impact on pollinators. The question came up by Friends of the Earth and others. Are the plants that we're selling at garden centers safe for pollinators? And we were really caught by surprise because nobody had asked that question before. And we had to go back and start from the beginning and see, okay, what information do we have? What are the gaps and what can we provide right now? So you're not the only one who didn't know how to answer some of those questions, but we've come a long ways in the last couple years.
Speaker 1: You know, a lot of our episodes focus on agricultural landscapes. We don't deal with horticulture. I think most of our listeners are really interested to learn a little bit about how we think about pollinator protection in horticultural industries as different from agricultural industries. What are some of the issues that sort of arise when we enter that sector?
Speaker 2: Well, we really have three ways to look at this. There's the homeowner in the yard and garden. That's one view. There's the professional landscaper, which is a different perspective. And then there's the nursery grower and greenhouse grower. So that's where all of our flowers are coming from. And they have to have good pest control.
And some of the challenges are extreme. I mean, there's white fly and thrips and they will ruin plants if they're not managed in the greenhouse and nursery. And in the past, we haven't worried too much about insecticide residue on those plants because they are perfectly safe for people and we weren't really thinking about pollinators. And now we are.
Speaker 1: Of course, I guess that's this scrutiny that has been on looking at environmental hazards in egg sectors because of their consumption. But there is this additional issue where in horticultural industries, you don't eat the food. But it seems to me another big challenge is that you're growing a lot of different species. You don't have the luxury as you do in agriculture, really thinking about pest management with two or three species. You often will be thinking about a whole myriad of different pest complexes and plants.
Speaker 2: Yeah, that's a unique challenge. A lot of people aren't aware of how difficult that can be. Just as one example, a lot of the insecticides and fungicides that we use can cause plant damage. And so they're labeled for you some particular plants. And when you're growing 250 different species of plants and you might have 20 or 30 cultivars of each, it's really difficult to avoid those phytotoxicity problems. So our growers have to be pretty careful. They have to produce really high quality plants because people won't buy them at the garden center if they have insects on them or insect damage. And at the same time, now we have to do this without leaving residues that are harmful to pollinators.
Speaker 1: And it strikes me as well. Another difference from some agricultural sectors is that pollination service is not that important. So there is a way in which traditionally our extension around agriculture and pollinators has really focused on that. There's probably not a lot of extension resources for people in the horticultural sector who are looking for solutions to working with pollinators.
Speaker 2: Well, right, right. There's a good reason that we we didn't worry about pollinators too much because all the flowers that you buy, including the trees and shrubs, are still going to look great without, let's say, bringing in honeybees to pollinate them. There's always been adequate pollination naturally and we've never had to worry about that as far as what the plants are going to look like. The only exception might be is if you're growing some vegetables in your in your garden. You know, otherwise all the trees and shrubs are just fine. And then the other reason we haven't worried about it too much is the plants that we have around the home are not really impacting professional beekeepers. So, you know, for example, 90% of all the bee colonies in michigan get shipped out to california to pollinate the almond crop. They they might one beekeeper might have 5,000 hives and they're not going to keep it in in an urban area. So, when people were starting to become more concerned about honeybee health, we really didn't worry about that too much for ornamentals.
And, you know, now now I think everybody wants to do what we can. Not just to protect honeybees, but native bees and monarchs and we have we have some really good strategies and our growers are doing a really good job.
Speaker 1: I guess the flip side of this as well is horticultural industries have the capacity to generate a lot of plants, especially in urban areas that have good nectar and pollen resources. So they, you know, at the same time that they have these pest challenges, they have this unique opportunity in being able to supply plants that are really good for a whole range of pollinator species.
Speaker 2: Yeah, you're exactly right. A matter of fact, they've done a couple studies in the UK where the urban areas were better food resources for wild bees than the agricultural areas. So it's an important resource and we we're certainly growing a lot of plants, especially the perennials and the shrubs that are really highly attractive to bees. They're really good food sources. So we want to get the information out to people so they know when they go to the garden center, they can pick up something like herbs, for example, which are just fantastic resources for bees. Yeah, and then some of the flowering trees are really important too.
Speaker 1: And you know, one thing that we'll talk about an extension publication that you really fantastic one that you published a couple years ago. The other issue is for some of the butterfly species having host plants.
Speaker 2: Yeah, yeah, and and we can provide those. So, you know, butterfly bush, some of the milkweeds, they're great for butterflies and that bulletin has a list of some of the best plants or butterflies, about 25 of them. So yeah, there's we can definitely do that. Welcome back, Dave.
Speaker 1: Well, thank you. I want to talk a little bit about strategies that people can take and I want to begin with this publication that Michigan State University has produced, Protecting and Enhancing Pollinators in the Urban Landscape. Can you walk us through the pieces of that publication and maybe from there go into, you know, how using a publication like that one can figure out what to do around their garden, their backyard or in doing landscaping?
Speaker 2: Sure, sure. Well, that this is a good resource for anybody that wants to protect pollinators around the home landscape. So it starts out explaining what are the threats to bees, why are honeybees, why are beekeepers having trouble keeping their hives healthy? And then it talks about how to make your home landscape a good place for bees to be. How you can have the right food plants there and how you can manage plants around the garden.
So it goes through all the basics. What are the best plants to have? How to avoid using insecticides. So you want to avoid putting in certain plants that you almost are required to use an insecticide to keep it healthy like the European white birch. That is going to require an insecticide. So you want to avoid those types of plants. You don't want to spray any open flowers with insecticide. Just about every insecticide that we have is toxic to bees. And then the bulletin provides some alternative management strategies. So how to use soaps, oils, and other products that are safe for honeybees when you do have a pest problem. And of course the best thing is not to use any insecticide at all. So it walks through all those steps.
Speaker 1: I really appreciate especially the kind of way it's broken up into plant choices for pollinators. But there's a really great section in there that I think is lacking and really requires someone with a horticulture background on how to establish plants in the first place. I think one thing that I sort of got from the publication is when selecting plants make sure they're healthy when they come home and then being able to consider that a plant can become under stress and be more prone to pest problems. It seems like all those features fill in a gap where you're considering it from the point that you buy the plant all the way through to enjoying the plant.
Speaker 2: Well that is one of the major reasons why people end up with pest problems. It's when they have stressed trees and shrubs. And it's because they maybe they didn't have the right hardiness zone or maybe they're drought stressed or maybe they're not planted correctly or maybe not at the right site. Some plants have some pretty strict pH requirements. So yeah if you do those things right then you won't need to use any insecticide. Especially after one year which gives the trees and shrubs long enough to grow a healthy root system.
Speaker 1: Can you talk a little bit about some of the different insecticide options? I know in the publication it really goes through in detail things like low impact and reduced risk pesticides. What do those categories mean?
Speaker 2: Yeah so there are some products we can use if we have a pest problem like let's say caterpillars are defoliating when your trees and shrubs that won't have a major impact on pollinators. So one of the best tools is BT, the Solsteringiensis. It will work on all caterpillars and it has no impact on honey bees and other bees at all.
So that's a really good tool for caterpillars. For soft-bodied insects like aphids and leafhoppers and plant bugs a pretty wide range we can use insecticidal soaps. The advantage of the insecticidal soap is that there is no residue problem for pollinators. So if you sprayed over the top of honey bees while they're on a flower that's probably not too good for the honey bees but once that spray dries it has no impact on them at all. The only thing is people need to be careful with the insecticidal soaps don't use too high a concentration or it can damage some of the plants. And then the horticultural oils which is could be used similar to how the soaps are used. Again there's no residue problem for honey bees and they work on a fairly broad range of pests.
Speaker 1: That's great and I think these kinds of specific guidelines are outlined in the publication which is really helpful. I just wonder are there some pest problems seem really difficult to control and I know there's been a lot of attention on neonicotinoids. Is there a role for neonicotinoids in horticulture or is it completely sort of avoidable?
Speaker 2: Well that's one of the things that we've had to do some research to answer those questions. There's been a lot of good work that's been done over the last five years and it's pretty clear that if a metacloprid or one of the other neonicotinoids appears in the pollin or nectar at a concentration of 20 parts per billion or higher it's going to be damaging to pollinators. We can use let's say a metacloprid as a basal soil dranch or as a trunk injection after trees are done flowering. Once they're done flowering bees won't be visiting them until the next year and we've done a study with linden trees which because they're so attractive to pollinators and we found that one year later the concentration of a metacloprid in the nectar of container-grown trees, linden trees was less than two parts per billion one year after application. So particularly in the nursery industry where you're growing in a high bark medium I think if you treat after the trees and shrubs are done blooming there's not, I mean at this point it looks like it should be pretty safe for the next year but you can't do it that spring though for sure.
Speaker 1: And I imagine that's been an issue is that there hasn't been a lot of work looking at residue carryover. That must, you know, in Oregon, we were, you know, we had this issue where an off-label application was made, but there wasn't a lot of work. Is this true? There wasn't a lot of work looking at the residue carryover and a lot of shade trees.
Speaker 2: Right, right. Okay. Yeah, yeah, that was definitely a gap in information there. So, we're doing a lot of research right now. We have an SCRI grant with about 10 entomologists, and we're doing a whole series of tests to find out what is safe. Are there any systemic insecticides that we can use in the greenhouse and nursery industry that will be safe? And what concentration can we use and how long do we have to wait? At this point, you know, what you can say is don't use any of them in the spring before you're selling plants.
So, and you could probably even back that up to say, in the last 10 or 11 months before you ship plants to the garden center, don't use the systemic insecticide as a soil application. It's just, it's too risky at this point.
Speaker 1: You know, given these, we're building this knowledge, and it's really great to hear about the work that's being done in your collaboration to work out some of these details. But given, you know, what we know, I know there's been a lot of calls and pressure on plant centers on some of the plants they're producing. Can you talk a little bit about that chain and sort of ways that plant centers could improve their practices or things that we really don't know about that the pressure may, the pressure on the plant centers may not be altogether kind of flushed out? Yeah.
Speaker 2: So, so what, what has happened that's had the biggest impact on our greenhouse and nursery growers is the pressure put on by the public and by friends of the earth. And, and I think they are doing us a service by bringing this issue to everyone's attention. He has led a couple of our largest buyers nationwide, Home Depot and Lowe's, to require their growers don't use neonicotinoid insecticides. So, that has really changed the way some of our largest growers are producing plants now. So, they're not using a neonex. But that alone doesn't guarantee that plants are going to be safe for pollinators because there's another systemic insecticide available to growers now called mainspring. And there is no, no requirement not to use mainspring, but yet that could be toxic to pollinators as well. And there's no mention about avoiding spraying open flowers, which is probably the single most important thing not to do. You know, don't spray open flowers. So that's, that's the first thing we tell all of our growers is the last two weeks before shipping, you can't use an insecticide over the top of the open flowers because that is going to be toxic to pollinators. Unless you use something like a BT or a soap or oil or one of the products and listed in the bulletin as being safe for pollinators.
But most of the insecticides would be toxic. And that the same thing applies at the garden center. They should not be spraying their flowers at the garden center with insecticide. Now, there's no legal requirement and Lowe's and Home Depot are not requiring them not to do that, which they should, I suppose. But that's the other thing, you know, we don't want the garden center spraying open flowers in the homeowners after they buy the flowers shouldn't be spraying open flowers.
Speaker 1: I suppose that's something I hadn't considered is when if a plant is and this comes up right in in the in the extension publication, if the plant is coming with some degree of past pressure already that may prompt the homeowner to start treating the plant. And that might be a high risk situation, even though a systemic isn't being used.
It may be a high risk, you know, spraying close to bloom kind of application. And that in the kind of that may not be conveyed at this point. No, we're thinking about it.
Speaker 2: No, right. We have a lot of education to do for protecting pollinators. We did a large national survey two years ago. Over 5000 homeowners were surveyed nationwide and asked questions about what they're looking for when they buy plants at the garden center.
And almost number. Well, I guess number one is they want the type of flower that they're looking for. And number two is they want it to be perfect. They don't want they don't want insects or damage on it.
And then somewhere down the line, three or four is, oh, it would be nice if there's if they're safe for pollinators. It's there, but it's it's down their list of priorities. But the interesting thing we found out is they are willing to pay more if we can guarantee that.
Speaker 1: Can you tell us a little bit about how how that a bit of an opportunity for a message of both that there's a bit of a market there might help the public and motivate them to become more educated, but also provide incentives back to the nurseries?
Speaker 2: Yeah, so one thing that's happened is a number of different growers around the country have developed pollinator friendly plant lines. And they put a big tag on the plant that says be friendly or good for pollinators. And there are types of plants that produce a lot of nectar and pollen.
So they're good food sources. And people see that when they go to the garden center and then they start to ask questions. And really, when people hear about the issue, we almost always get a positive response. You know, maybe 95 percent of the customers think, yes, we want we, you know, we need honey bees and we want to protect them. There is a small group that really don't want bees around their home, but they're in the minority.
Speaker 1: Tell us a little bit about the Grow Wise Be Smart initiative. There seems to be a coming back to the horticulture industry itself developing best management practices. How did that initiative come together and what is it designed to do?
Speaker 2: Well, the Horticultural Research Institute started working on this because they they do research that supports nursery and greenhouse growers. And they put together all the most recent research and asked some of the researchers that come together and apply this to what would help growers produce bee friendly plants. And some of the things we've already mentioned, the guidelines are don't use any systemic insecticides in the last 10 months before sale. Don't spray open flowers the last two to three weeks before shipping. They also have guidelines for landscapers.
Pretty much the same type of thing. Don't use the systemic insecticides on plants that are attractive to bees. So if you wanted to treat a juniper, for example, or a pine tree, bees don't visit junipers and pines. They don't visit any of the conifers, so we're not worried about it. But if you have a nice flowering almond or crab apple, something that bees like, you should not be using systemic insecticides.
And the one exception would be to wait until they're done flowering. So out here in the Eastern states, we have a big problem with emerald ash borer. And it's so bad that the trees will die if they're not treated with insecticide. And the recommendation is to wait until the ash is done flowering, which is early May. Then do your trunk injection. And that's going to be pretty safe for pollinators.
Speaker 1: So this the these best management practices allow landscapers and nursery growers to be able to deal with some very simple steps with their pest problems in a way that can reduce exposure hazards to pollinators. Right.
Speaker 2: Right. For example, a lot of people didn't think about lawn care. So there's different areas around the country where there's a problem with grubs eating the turf roots and causing some damage.
And a lot of the lawn care companies have been using a systemic insecticide. It's usually a metacloprid or one of the neon next for grub control. So it was just a matter of thinking this through. So if you have dandelions or clover in the lawn, you don't want to apply those insecticides when they're blooming. So there's a real simple remedy to that. You mow first. So there's no flowers present when you spray and that minimizes any impact on pollinators. And then also there's an alternative product, a celapren, which is pretty good for grub control that is safe for pollinators.
Speaker 1: So you get good grub. You're able to get good grub control. And just by mowing out the flowers, you're able to reduce the risk is the pollinators won't be visiting that turf.
Speaker 2: Right. And by the time the clover blooms again, let's say three or four weeks later, there's not enough amid a cloprid to make it into the nectar to harm them. And there's been a couple of good experiments done to show that.
Speaker 1: That's great. I guess one last question before we take a break here. Can you walk us through some of the pest prone plants? What are, if we were to go across the country and look at the real, the points where exposure, pesticide exposure of pollinators might be most acute because there's a pest problem that's very close to bloom. What are some of those really, what are the ones that we should keep our eye out for?
Speaker 2: Well, here in the, in the Eastern U.S. ash is a problem because of emerald ash borer. And then the linden trees, if you have an outbreak of Japanese beetle and you're not going to have that problem in Washington, but here we can have linden trees defoliated.
So that's, that's a problem. And again, the, the, the remedy is this is to wait until after the trees are done flowering before you apply any insecticide. Crab apples, which is one of the most popular landscape trees anywhere, Washington or Michigan. People have used fungicides, uh, we, that can also be a problem for bees. If you apply the fungicide when they're in full bloom, so it's better to, to use a fungicide before and after flowering.
Speaker 1: And one that we worry about out here is azaleas. We have azalea lace bug as a, right, right.
Speaker 2: And that didn't, uh, I didn't think of that right away because we don't have much in, in Michigan. It's just too, too cold. But yeah. Yeah. Azalea is a very popular, um, shrub, and it's very attractive. So you would want to wait until they're done flowering. And, and unfortunately there's a nice window there with azalea.
If you just wait until they're done flowering, and then if you, if you need to care of your pest problem, you can, and it should be safe for the next year.
Speaker 1: Okay. Welcome back. And hi, Dave. I want to end the interview off by looking to the future. And I know one thing that horticultural industries, you know, really under threat from are invasive pests. Can you talk a little bit about invasive pests and how they may, you know, change the game with, uh, or make it a lot more difficult to work around pollinators and horticultural industries?
Speaker 2: Well, 90% of our pest problems are now invasive species. And the reason why is we don't have the right natural enemies here. We don't have the predators and heresitoids and diseases that keep them under control, like where they came from.
And so the populations just go out of control. And so things like Japanese beetle, gypsy moth, hemlock, willy-a-dell, jid and a whole host of other invasive species now occupy most of our pest management efforts. If it, if it wasn't for the invasive species, we would have to use very little insecticide. We could rely almost completely on natural control, but because we're not getting good natural control at the invasives, then we have to use insecticides on some of those. And then the nursery industry is, is particularly, um, susceptible because they have to be inspected and their nursery stock has to be certified as free of pests before they can ship out of state. And we have federal quarantines on some of these pests, like a Japanese beetle.
So they cannot have even one Japanese beetle and any of the nursery stock coming out of the East. Yeah. Yeah. Out of the Eastern States, if they're shipping West. So, yeah, they're under tremendous pressure to produce high quality plants without any invasive present. And that's, that's really tough to do.
Speaker 1: Well, I want to end the show. We ask all our guests three questions, uh, all the same questions. And I want to start off by asking you if there's a, you know, if you've come across a bee book that you'd recommend or, um, that's been really important to you as you tried to deal with this, uh, issue of, uh, pests in the urban landscape. Yeah.
Speaker 2: I think one that I just, uh, found out about a few months ago, it's really a fun book and very informative is the bees of Toronto. It's a really entertaining and it gives some great information on bees and including all the most common ones in the Toronto area. Take a look at it. That's a fun book.
Speaker 1: It's a great book. And thanks for plugging it. Scott McIver is going to be on in a few weeks to talk about, talk about the book. It's really, Oh, great.
Speaker 2: He, he, he's also our keynote speaker for our pollinator conference next October. And I'm going to say to Michigan,
Speaker 1: can you tell us a little bit about the conference I'm going to be there? I'm really excited that Scott's going to be there, but what's the conference about?
Speaker 2: Protecting pollinators in urban habitats. That's the, the focus of the conference and we'll have about 25 of the top speakers from around the US and around the world. Um, let me see. Let me give you the dates for that.
So it's going to be October 9th to the 11th in Traverse City, Michigan, which is a beautiful part of the state at the Park Place Hotel. So we only have about 200 slots open for this conference. So register early if you want to, and you can just go to the, protecting pollinators website. So if you Google that, you should, protecting pollinators conference that should pop right up.
Speaker 1: And we're going to link, um, the notice to the conference on the show notes for guests. So, uh, in case you didn't catch it, just visit the show notes and we'll have it there. Great.
Great. Now here, another question is, uh, is, is there a tool that you use for doing B research that is indispensable? Really important to you or you'd like to let people know about? Yeah.
Speaker 2: One of the most valuable tools that, that we've used are bumblebee colonies. So we get bombas and patients from bio best. They, they produce these in large numbers for greenhouse growers that are growing tomatoes and cucumbers under glass because they have to be pollinated. So they put the bumblebee colonies in there and they're also used for strawberries and other outdoor, some outdoor crops as well. So we get the bumblebee colonies and then we can do things like, uh, do a basal soil drench around a tree after it's done blooming and save that tree until the next year and then put the bumblebees in screen cages and see if it has any impact on them. So that, that's been a nice tool for us.
Speaker 1: That's great. And I just remember earlier in the interview, you talking about this kind of research, uh, helping us figure out how to use some of these compounds safely around trees, shade trees and other plants. Right.
Speaker 2: Right. And that, that's one good way to do it. I mean, I, you, you can also collect a nectar and find out, you know, how much insecticide is there, but you also need the biological part of the test with the live bumblebees.
Speaker 1: That's terrific. And just, uh, I'm wondering, are bumblebees your favorite, uh, species of bees? Is there a species that you're just really drawn to when you see it fly by?
Speaker 2: Well, I, I really like the sweat bees because they're so brightly colored. So these are small native bees are only about a quarter of an inch long, but they're often, uh, bright fluorescent green and blue. And that's probably my favorite group.
Speaker 1: I noticed that, uh, the city of Toronto has now named, uh, uh, uh, elected as its, uh, uh, bee of the city. So, uh, you're, you're not alone. There you go. Well, Dave, thanks so much for taking the time to talk with us today. And, uh, any of the information that Dave's talked about, we're going to link below in the show notes. And, um, we're really looking forward to, uh, I'm looking forward to attending the national, uh, conference, the horticulture conference on pollinators.
Speaker 2: Yeah, great. I'll see you up there in Traverseater. It is a beautiful area. So I think you'll enjoy the visit. Awesome. Thanks so much, Dave. Okay. Thank you.
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 could 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.
It makes us more visible, which helps others discover pollination. See you next week.
Dr. Dave Smitley is a professor and researcher at Michigan State University.
He works with the turf grass and nursery industries to deal with emerging pest problems, and the greenhouse industry to grow plants in ways that are safe around pollinators.
In this episode we talk about practical tips as well as national initiatives to protect pollinators in urban landscapes.
And be sure to leave us a Rating and Review!
“You want to avoid putting in certain plants that you almost are required to use an insecticide on to keep it healthy.” -Dave Smitley
- How Dave began to research the safety of plants at garden centers for pollinators
- How pollinator health is different in horticultural industries than in agricultural industries
- How butterfly species are also part of the research into nursery plant health
- Strategies that people can take around their garden to protect pollinators
- What the modern threats to bees are
- Why people end up with pest problems in their gardens
- The products you can use to get rid of pests that won’t bother bees
- How the largest plant centers have been pressured to change how they get their plants
- What to look for when you are buying plants at the garden center
- How nurseries have developed pollinator friendly plant lines
- About the GrowWise BeeSmart initiative
- Why lawn care effects bees as well
- Some of the most pest-prone plants to keep your eye out for
- How invasive pests change the game
“We have a lot of education to do for protecting pollinators.” – Dave Smitley