The Ruminant: Audio Candy for Farmers, Gardeners and Food Lovers - e.07 Pest Management with Entomologist Tamara Richardson

Episode Date: August 14, 2015

This episode: I speak with entomologist Tamara Richardson about strategies for insect pest control in the garden. We discuss the merits of crop rotation, the importance of knowing your pests' overwintering habits, and what to do with plant debris that's infested with insect pests.

This is the Ruminant Podcast. I'm Jordan Marr. TheRuminant.ca is a website dedicated to sharing good ideas for farmers and gardeners. At The Ruminant, you can find past episodes of this podcast, essays I've written, a few book reviews, and a whole lot of photo-based blog posts, some of which were made by me and some of which were submitted by you. So I hope you'll check it out, TheRuminant.ca. And if you want to get a hold of me, editor at theruminant.ca or at ruminantblog on Twitter. Okay, let's do this show. Hey everyone, it's Jordan, the host of The Ruminant, and I just want to give you a brief new message before the episode gets started. This is a rerun, it's episode 7 with Tamara

Richardson. Tamara is a friend of mine who lives a couple valleys over here in the interior of BC, and she is an entomologist who came on the podcast a couple years ago to share some information about managing insect pests on your farm. And I think you're going to like that. But before we get started, I just want to mention that there's light at the end of the tunnel. I think it won't be too long before I can start offering new content again. It has gotten pretty tricky to manage the podcast with my full-time farming this season, but we're almost through the real peak part of the season and more importantly I had an offer from well a former guest on the

program and a fan of the show to to help me a little bit with the podcast and since then we've spoken a little bit and I think he is indeed going to help and I think that is going to be really great for the show. I won't mention his name yet because we're just kind of at this point just going to work together a bit and see how it goes and I don't want to make too big of a deal out of it yet because well I'll let Elaine Bennis explain why. I'm trying to get a little squirrel to come over to me here. I don't want to make any big sudden movements. I'm fighting it away. I'm just kidding around. The point is, it looks like I'm going to have a bit of help with the

show, at least for the next few episodes. I'm thrilled about that. And I'll just talk a bit more about that probably next episode, which will be in the next one to two weeks. All right, so here is episode seven, Entomology with Tamara Richardson. I hope you enjoy it. Today's guest is entomologist Tamara Richardson. In our conversation, we discussed three strategies for controlling insect pests in the garden, including crop rotation, knowledge about pests overwintering behavior, and proper management of crop residues that contain unwanted insects. So let's get right to it. Tamara Richardson, thanks a lot for coming on the Ruminant Podcast. You're welcome. Tamara, you are a researcher and crop management consultant and you are an entomologist and beyond that terrible introduction I'm going to ask you to

describe a little bit about what you do and your background as it relates to agriculture. Sure. Thanks, Jordan. Well, I started off during my undergraduate degree working on greenhouse insect pests at a lab there and then I moved on to do a master's degree at UNBC looking at different ways of managing stink bug pests in conifer seed orchards. And following that, I got a short contract in the Similkameen Valley to work on pest management of aphids in organic apple orchards. And then fell in love with the area so much that I decided to move down here and start my own consulting company where my work consists of doing research

on organically acceptable methods of pest control for tree fruit pests. pest control for tree fruit pests. And I've been working a little bit in troubleshooting problems on a few organic veggie farms. But that's relatively new for me and not a system I'm totally familiar with, but I'm becoming more familiar with. Okay. And well, since I'm a veggie grower, I think I'm most interested in talking about ground crops and veggies and that sort of thing. I understand that you're pretty new to the ground crop pest management, but can you talk a little more specifically about what you're working on? Well, I've been helping this one grower try

and get a handle on his aphid problems. And not this past year, but the year previously was a particularly damaging year. And we experimented with a few things. These were aphids on tomatoes. We released a bunch of different biological controls and tried to remove the alternate host of that aphid from around the area. But most of the work involved basically trying to release biological controls to manage this particular aphid population, which wasn't... We were, because of the severity of the issues, we were unable to have a control to actually test the efficacy, but the problems did eventually get cleaned up, but we weren't really able

to tell if it was due to the release biological controls or the naturally occurring ones. And when you say release controls, do you mean ladybugs? Do you mean wasps? What are you guys releasing? Both. Ladybugs, wasps, and midges. But when I'm talking about a control, I'm talking about a control plot where we didn't release anything.

Which it's one thing that a lot of people do is they try these new method methods say you try and release the biological control you try a new product but you don't leave an area where you're testing the difference between the area where you're applying the particular control that you're using versus and then if something goes away people automatically jump to the the conclusion that whatever they did worked but but they haven't they haven't set up a proper uh but they haven't set up a proper control against which to test what you would test yeah right yeah okay what was what was actually going on.

I'm particularly interested in the topic of aphids because in our veggie garden this past season in the Okanagan Valley in BC, we had terrible aphid problems. And I'm quite certain it's the cabbage aphid. And it was mainly affecting our various brassica crops uh particularly our kale just got hammered yeah i'm really interested in in figuring out what i could be doing differently and you mentioned i heard you mention um you know overwintering uh where like um the alternate host for aphids when okay in the winter or that sort of thing so yeah i'm just maybe you could start by talking about that can you talk about alternate hosts and what's happening in the aphid life cycle? I'm really curious to know what, where are these aphids going over the winter? Because our kale plants, a lot of them, there's some, a couple of beds that are still standing out there that are basically

done and destroyed, but we didn't, we didn't do anything with the plants or any of the debris around them. And I'm wondering if that's going to be a problem. It very likely could be. I am not up to speed too much on the actual life cycle of the cabbage aphids have several generations in a year. And so typically there's an overwintered egg hatches in the spring, and they cycle through various several asexual generations, have a sexual generation late at some point in the late summer, early fall, that sexual generation. And then they lay the eggs. So during the summer, what happens is, or I'm speaking mostly about an apple aphid, but there's a lot of generalities that can be applied to these aphids.

So what's happening is that your aphids are building up in your crop, and they're also spreading out as they form winged forms, and they're going to spread through your crop system. And there's also related weed species in the area. Yellow mustard's a big one that the aphids can also survive on. So you might get rid of everything in your garden, but there's still going to be that species of aphid will still be out and about in your system. I don't know if there's been a lot of work done, but it is possible that you could help

by removing as much of the mustard, weed hosts that are related to your crop, and I think you're talking about brassicas now, that I've seen sort of anecdotally that work in other systems on a small scale. Right. And then also removing really infested plant materials and not just throwing them in the compost but but even putting them in a bag solarizing them and killing the okay okay so that's i was yeah i'm curious about two things you mentioned the first is i think i've noticed that the first time i see aphids in the

spring is not on the kale and by the way the kale is one of the first things that are out in the garden that we have in the garden i i think I think I've noticed that prior to the, the populations building up on the kale, um, they're building up on, uh, um, like a ragweed that, that grows is a common weed in the garden. And so one, one thing I've been curious about the first season, my instinct was to pull it all out. But then I was thinking like, well, if they if they have a you know a preference for that weed is it better to leave them in and allow those populations to the aphids to to go for those weeds rather than rather than the the main crop but you're suggesting the strategy is to remove them get them out of the garden remove them um i think the ragweed, as far as I know, the cabbage aphid will only feed on brassicas. And the ragweed, I think you might be seeing another type of aphid.

But there are early mustards out too yeah so um and actually just while i'm talking to you looking on the internet um i have i found some information that the the cabbage aphid overwinters is a as an egg in a host plant debris. So I think that it might be worthwhile clearing up your, your old plants and getting rid of that plant debris, because if you're leaving it out, then those eggs are going to hatch in that same area that you had the problem the previous year. Right. Okay. So so all right so so uh approach

number one or strategy one you're recommending is when i find weed hosts anytime during the year to remove them um i mean i'm removing weeds or regular like removing what you can but not just within your your plot but on the periphery, right? I know that's far easier said than done. But even regular mowing of those areas could have a beneficial effect, or early season mowing, or mowing in the fall, and then taking those plant materials. And if you're composting properly,

you could incorporate those into a compost and and kill those eggs too. And by properly you mean turning them enough to bring the temperatures really high? Yeah getting that getting that temperature up to between 45 and 65 degrees Celsius. Right okay. A couple of times. You're going to do yourself a huge amount of favours for not just aphids but probably other pests if you do use proper composting. Because you're going to be killing, you can kill if you've got say, culled vegetables or you've got, you know, you see through your, I mean, not that you should be throwing garlic infested with onion maggot just randomly in a pile, but if you manage your waste residues and properly compost, you can kill a lot of, you can kill pests that are overwinter or are in those residues by using a proper composting. Okay. Now, one thing I can say about our composting here on this farm is that for whatever reason I struggle to get my piles, and these are all veggie residues, there's rarely any manure in them, up to heat heat and earlier you mentioned

solarizing your debris that you know is infested and so i'm this is really good to know that was another question i had is inevitably during the season a lot of as we're just dealing because you can still harvest a lot of the crops with aphids you just we just end up having to wash them and stuff but inevitably there's a lot of debris involved yeah but you're recommending it's if you're if you're not confident confident about the temperature in your compost piles, to do something like solarize or, I would guess in a worst-case scenario, burn that residue. Yeah, you could burn it. I mean, you can also, I mean, if you don't, I mean, I know that when you're in the season,

you're incredibly busy. You can, if you have heavy-duty garbage bags, you you know throw the stuff in those garbage bags seal them put them in the sun leave them they're going to be nasty to deal with later but you can incorporate that material into a compost pile later and you can have the confidence that whatever is in those piles is dead right because you you know with the lack of oxygen and and the beginning of decomposition you're going to get the heat the heat's going to go up in there yeah plus with the additional heat of the sun that's a way to kill contain a beast contain insect pests that are on on plant waste materials that you're not actually able to deal with at the time

and would that apply would that apply to onion maggot? Because we have that problem here as well. That would apply to onion maggot too. Another, that definitely apply to onion maggot. But you want to make sure you seal your culls and leave them for a week or two, making sure that they're in the sun so that you can get those high heat.

And then that material can be incorporated into your compost pile. And again, if it's working properly, you're not going to have to worry about that. But if you're not sure you're reaching those temperatures, that's a way to make sure that you're not going to increase your problem i mean with with onion maggot the most important one of the most important things with onion maggot fly is rotating your garlic crop year to year okay well let's jump to the topic of um of crop rotation because that is a mainstay of organic growing and again it's not it's not considered mandatory by your certified organic inspector, but they are encouraging it or, or the very least, they want to see you have a pest and disease management plan. And one of the most endorsed

ways to have a plan is to do engaging crop rotation. But as an entomologist, you can, you can, I mean, I worry with certain aspects of the organic philosophy that they're more based in received wisdom than science. But as an entomologist, you can really endorse that notion of rotating those crop families to make the test. Yeah. And there's some science behind it, too. science behind it too. And we spoke earlier of overwintering. We were talking about where these aphids overwinter.

But some other pests, a lot of fly pests and certain moth and butterfly pests or larval pests, they spend the winter in the soil, and beetles as well, certain beetles as well, the pupa or the puparia. They overwinter in this dormant stage,

and then if you go back the next year and you have a crop in the same family and you plant it in that area you've already got you've already got a pest population right there they don't have to move very far to find uh what once they emerge and start feeding and go through the reproductive cycle they don't they don't they don't have to go anywhere the food their their preferred food system food is right there because a lot of these pests are at very least families family specific um right right but one thing i've wondered is that like

what if i mean how how far how far can pests move because um you know we have one main garden here that's only about between half and three quarters of an acre and in that in that section that we have eight different blocks and those are the blocks that get rotated right and each set of 12 beds gets moved to the next block over so if i move it so that essentially the same bed of the same block gets moved it ends up getting moved 60 feet right is that where they get moved 60 feet well not actually not even if you if you look at it this way in my rotation so yeah like there's 12 beds in each block and then but then the next block over i mean there's a bed so bed one of the next block is right beside bed 12 of the previous one so yeah if you assume that the brassicas are going to get shifted over to the next block um you know the first bed of brassicas the next year is right beside bed 12 of last

year's block. And so I'm just, yeah, I'm trying to get a sense of how far can pests move, you know, to what extent. It depends on the pest. It absolutely depends on the pest. Certain things don't move very far. Certain things don't fly as much as others. Certain things are good flyers.

Certain things are poor flyers. things are good flyers, certain things are poor flyers. And certainly, for some pests, the rotation isn't going to be as much of an issue or isn't going to solve as many problems, say, as another. However, it is often, not speaking about aphids at this point, but speaking about fly and larval pests, it's that young generation, the larval farm obviously, that are the biggest feeders, right? Yeah. And so if you've got... So and often, for the most part, the plant that an insect is feeding on is the plant that they reproduce on and lay eggs because these babies can't move very far. A larva isn't gonna move very far.

An adult fly, an adult aphid can fly and they can get picked up on the wind and they can get moved. But I mean, everything has sort of a finite energy budget and a lot of the adult forms of these insects aren't as big of feeders as the larvae. Basically, you've got something emerging. The first thing it wants to do is to go out and have sex and have babies, right? and they want their babies because their babies can't move around the babies need to have their particular host plant so if you're planting year after year the same thing in the same area you might not have any problems for a while but as the population starts to build up you're making life easy for them right so their host is there okay boom gonna have, going to have my babies.

Okay, look, my food's here. I'm not going to go anywhere. The babies are there. And so if this goes on year after year after year, you're going to have more. Population's going to build up. Obviously, you're going to have more natural enemies eventually coming in, but your population's building up. And then they're going to obviously be what's those that young generation matures, they're going to disperse, but you're still going to have a resident population in that patch too.

So year after year, if you don't move it, you're building it up in that area. Whereas if you move it to a completely different crop group, okay, so you had a pest problem one year. Then you say you had your cabbages. Well, and then the next year, okay, you're going to put some eggplants there. Well, your cabbage fly, it's going to wake up and it's going to be, there's an eggplant. It doesn't eat the eggplant. So it's not going to be successful. It's going to die because there's no food.

Right, okay. successful it's going to die because there's no food right okay the way it sounds with your rotation if you're moving if you can try and like set up your rotation so that maybe things aren't going direct one crop group isn't going directly adjacent to where it was the previous year if you can have a bit of a gap in there like maybe maybe moving everything, skip a block with each, so everything moves too. So everything, yeah. I mean, you can probably work this out on paper, but if you can skip a block, it's not going to be a cure-all for everything, but it's going to help. So I think with good rotation and cleaning up the plant residues that might harbor a pathogen and other, you know, eggs of other individuals of the population of that pest. It's going to help.

But overall, it really sounds like it's worth, with any given pest, going online or wherever and finding out how that insect overwinters, in what form of their life cycle, and where they are. Absolutely. Finding out the life cycle. You find of the life cycle you find out the life by figuring out the life cycle and then looking at that and seeing if there's any part of the behavior of that insect that you can exploit I mean where does it lay its eggs where does it overwinter does it overwinter in the soil well maybe once you've cleared out your area is in addition to doing these other these other uh things that we we talked about cultivating right because perhaps you can chop up at least some of the the puparia

or the overwintering individuals if that's where they happen to be right and do you know of any like what's what's your go-to or what should a farmer's go-to online resource be do you know of any, like, what's your go-to or what should a farmer's go-to online resource be? Do you know of any? Yeah, I go to the UC, University of California, IPM online site a lot. And they're quite, I mean, they have a different environment, but they have growing environment, temperature, climate, et cetera. But they've got a really, they've got great pest descriptions.

They've got great damage descriptions. They've got conventional management tools, but they also talk about different cultural control that you can possibly use as well. And on that site, are they going to talk about, are they going to lay out different stages of the life cycle and overwintering characteristics and stuff like that um not always they do have they do have some the unfortunately we don't have uh i find that there's a lot of really good information on the university extension websites in the U.S. University of Washington, University of California, University of Oregon, and the University of Minnesota. There are great, there are good agricultural integrated pest management resources.

And they talk about different insect pests by crop, and they provide a lot of information on... If you use a combination of a couple of these sites, you should be able to find out what you need. Okay. Yeah, I find these are really good resources that typically have, which is applicable to organic growers, sections on control, like cultural control methods and what the biological controls are. You mentioned that you used soap.

I'm not sure how much that would have helped you. I've found that it's not particularly effective. You might get a little bit of suppression, but I think cleaning up your area, cleaning up, using sanitation methods post-harvest and throughout your harvest, throughout your growing season, coupled with trying to manage your alternate hosts, and it's going to have the best effect.

Did I say crop rotation? Coupled with crop rotation. Tamara, thanks so much for coming on the podcast and sharing your very valuable insect knowledge with our listeners. No problem. So that's it. I hope you enjoyed that, folks. And before I sign off on the episode,

I do want to share the website that Tamara was talking about, the UC Davis site. The actual site is IPM, as in Integrated Pest Management, ipm.ucdavis.edu. I've taken a look at the site and it looks really cool. So do check that out sometime. Thanks for listening. And I hope to be publishing or broadcasting again in about a week or so.

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