
Succulents & Pesticide Modes of Action
Season 12 Episode 42 | 27m 6sVideo has Closed Captions
Dale Skaggs talks about succulents and Mr. D. discusses pesticide modes of action.
This week on The Family Plot: Gardening in the Mid-South, Dale Skaggs, Director of Horticulture at the Dixon Gallery and Gardens, discusses succulents. Also, Mike Dennison, Retired UT Extension Agent talks about pesticide and fungicide modes of action and how to avoid pesticide resistance in insects.
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Succulents & Pesticide Modes of Action
Season 12 Episode 42 | 27m 6sVideo has Closed Captions
This week on The Family Plot: Gardening in the Mid-South, Dale Skaggs, Director of Horticulture at the Dixon Gallery and Gardens, discusses succulents. Also, Mike Dennison, Retired UT Extension Agent talks about pesticide and fungicide modes of action and how to avoid pesticide resistance in insects.
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Learn Moreabout PBS online sponsorship- Hi, thanks for joining us for the Family Plot: Gardening in the Mid-South, I'm Chris Cooper.
Today we're going to talk about growing succulents.
Also Mr. D is going to talk about the different ways insecticides kill bugs.
That's just ahead on The Family Plot: Gardening in the Mid-South.
- (female announcer) Production funding for The Family Plot: Gardening in the Mid-South is provided by The WKNO Production Fund, the WKNO Endowment Fund, and by viewers like you, thank you.
[upbeat country music] - Welcome to The Family Plot, I'm Chris Cooper.
Joining me today is Dale Scaggs.
Dale is a Director of Horticulture at the Dixon Gardens, and Mr. D is here today.
- Howdy.
- Thanks for joining us.
- Thanks for having me.
- Alright, Dale, let's talk about succulents.
So what do we mean when we say succulents?
- Well, succulent plants are typically thought of as, well I like to call them fat lazy plants.
Because their tissues are soft of swollen and very fleshy and that's how you identify them as succulent plants.
A lot of people think succulents are cacti.
And it's true, all cacti are succulents, - But?
- But not all succulents are cacti.
- Alright.
- They're soft of defined by these little spiny cushions that they have where the spines are emerge.
You know, because some succulents have spines, but they're not coming from that spiny cushion.
And so that's the distinguishing characteristic.
I happen to like the succulents that don't have spines because when you're a gardener you hate dealing with them.
- (Chris) Right, exactly.
- But it's pretty amazing, these plants have evolved these defense mechanisms and traits for survival because they store water in really water tight conditions.
So everything wants to eat them, everything wants to, you know from herbivorey to just surviving just the heat and everything else, they're pretty amazing how they adapted to survive.
- What kills more succulents than anything else?
- Probably over watering, over watering.
We have a succulent exhibition right now at the Dixon and one of the things that we have are some living rocks, some lithops, I don't know if you've ever heard of lithops, they're from South Africa.
And they look like stones, they use mimicry as their defense mechanism.
We have a plant that's euphorbi that looks like sticks.
So, the leaves are modified so it looks like dead sticks.
And the lithops look like living rocks is what they call them, they look like rocks.
So, nothing eats them because they just, sort of, they're disguised, I guess, in hiding.
So anyway, they're from South Africa.
What I was gonna tell you, I have killed lithops more times than, you never water them, that's the key.
If you ever water them they're just gone.
So occasionally you see them at box stores and stuff they'll have these living stones and they have a pretty heft price tag, but I think they're real slow to grow and really difficult.
- So they don't have to be watered, pretty much, not at all?
- They grow in South Africa in conditions that are really, really arid and hospitable so it's really dry west-facing conditions.
But anyway, if you think about it, there's all these different mechanisms.
You know, some plants actually separate, there's sort of a day, night separation in their photosynthetic process where they're splitting CO2 to build, you know, basic photosynthesis that you learn in elementary school, but CAM plants, as they're called, which it's long term is crassulacean acid metabolism, but CAM is what you need, CAM plants.
They actually open their stomates, the little pores under the leaves at night so they can take in the CO2 at night, they hold it in, and then when the sun's shining during the day they do photosynthesis.
That way if they were to open those pours when it's so hot outside, all the water would just instantly desiccate.
- Especially here, yeah.
- But these succulents are really, really popular.
You know, you go to, I was at a local grocery store and I walk in and they have this succulent display.
Everybody just loves them because they're easy to care for, you know.
Because of these adaptive advantages, they're used-- You know, a lot of these are hardy outdoors and they're being used as, sort of, the back bones or the work horses of everything from green roofs, you know.
There's a couple green roofs in Memphis, but they haven't really caught on.
More urban areas like Chicago and New York and stuff, these green roofs are a really big deal.
I think there's acres and acres of green roofs in Chicago and there's tax incentives for businesses that incorporate this into their thing.
So anyway-- We need somebody to introduce those practices here, though.
To get involved with it.
- I think Trezvant Manor here has a green roof and there's a doctors office out in Bartlett I think that has a green roof.
But, certainly the technology's there.
- Oh, sure it is.
- Just like, you know, all the questions you get, everything's so localized and in Memphis it works one way and somewhere else it might not work the same way.
So, really a lot of research needs to be done on which plants work best.
We've put in a little green roof at the Dixon which was kind of fun, it's just a small space, but it's kind of neat to see.
And then living walls, do you know about these living walls?
- (Chris) I do.
- Sort of vertical gardening.
They're real easy to build, we just sort of used recycled materials, they're repurposed.
Susy Askew had kept these big long troughs that were used for something horticulturaly, I don't know if it was hydroponic thing or something, but, big galvanized troughs and we made a media that's real lightweight and filled these troughs with succulents and so now they're sort of louvers and it's a vertical garden at the Dixon, it's really neat.
- Tell me what it is, what type of media do you need for succulents?
- Well, fast draining sharp media, as you would suspect.
Fast draining, you don't want anything that holds a lot of moisture.
And they're not big nutrient hogs so they don't need a lot of high nutrients.
So, if you had potting soil that you wanted to use for succulents, I would just mix in some sand, a little gravel or something.
There used to be a product made across the river that's this clay that they heat up real hot and expand it.
You ever here of arcilite?
- Arcilite?
- Arcilite.
It used to be sold over in Arkansas, now I think the nearest supplier's down in Alabama, but I'm not sure what the product was originally used for, but it's like clay that's been expanded, it was a lot of pore space.
You know Paul Little.
- I do, of course.
- He's, anybody's-- - The sedum guy.
- Talking succulents in Memphis, you gotta know Paul.
But Paul said he used to drive over to Arkansas and get it and the first time he went over there in his little Toyota pickup truck, he said by the time he made it back to his nursery his truck was empty because the stuff flew out.
- Oh, wow, okay!
So it's real light.
- It's real lightweight.
- Bitnite.
- It may be heated bitnite, I'm not sure exactly the product.
But that works really well for green roofs because it's lightweight.
- Okay.
- Different considerations when you're going vertical or covering a rooftop, you know.
- Let me ask you about sedums for a second 'cause folks grow a lot of sedums.
Again, what type of care do you need for them?
'Cause we actually got a couple calls at the office about people growing sedums, but the sedums were rotten, rotting for some reason or the other.
- Yeah, you know, first of all you need to buy good quality plants from a good nursery that know what they're doing.
I've seen plants where slugs or snails get in there and can cause some damage.
I've seen sow bugs, and I think they're actually eating some of the root, they may be secondary.
What are your thoughts on?
They can, sow bugs and pill bugs can actually eat foliage.
- So I've seen that.
- Plant material.
- In general, you put them in, you water them in initially when you plant them to settle the soil and get everything done and then they're really, really low maintenance.
- That's what I thought.
- Cut the water down to a third of what you would normally do, I'd say, something like that.
So, I imagine over watering is probably the best way to kill them if you're trying to get rid of them.
- I imagine you have good drainage, but we've gotten that question a lot here lately.
So just wanted to run it past you.
- They're beautiful, a lot of - They are, they are.
- different colors and there's a lot of, from small to large, there's a lot of sedums.
A lot of succulents.
- Alright, we appreciate that and we can tell that you like talking about succulents, too.
Thanks for that information.
[upbeat country music] Sidedress is our next term.
And of course, we hear that all the time... - Yeah, yeah.
- in vegetable gardening.
- And that's a term to describe a type of fertilization.
- Okay.
- You know, you how you do that.
You know, we can broadcast, just get out there and just throw it every which way.
That's called broadcast.
And then, we have sidedress, and there's other terms as well for other types, but we're gonna talk about sidedress.
And, that's usually in vegetable gardening.
And, you do that at a certain stage of growth when the plant is needing another big boost of fertilizer particularly nitrogen, to help them keep growing through the growing season.
And to sidedress, you just open a trench right beside the row away from where the seeds are, but close.
You know, you don't want to burn the roots, and you just pull a trench and then just put your fertilizer there.
Hence, sidedress, yeah right.
[chuckles] And, some of the other crops that we sidedress are, typically, are the vining crops, vegetable vining crops, like cucumbers, some of the squash that we have that vine, watermelons, cantaloupes.
And, we usually do that when they just begin to, what we call, run, you know, when they start vining.
[upbeat country music] Alright, Mr. D, let's talk about pesticide mode of action.
Very important, especially when you're talking about dealing with those pests that are out there.
- Right, insecticides, insect mode of actions and a little bit of fungicides, there are -- Important to understand that there are different modes of action of these different products.
And my first introduction to insect resistance was in was in 1978, '79 when I was doing some work looking at a new product called insecticidal ear tags on cattle to try to prevent, to kill horn flies and face flies and things like that in cattle.
And we learned very quickly that the ear tags were impregnated with a new, relatively new class of product called a synthetic pyrethrin, or a pyrethral.
Which is, and it worked real well for a year or two and then we started noticing that it didn't do as good a job.
And I can remember that some of the folks denying that there was such a thing as insect resistance.
And then after a very short while they had to admit, there is.
And I also, as an extension agent, I can remember recommending Seven to kill fleas.
And I remember that the dosage went up and after a while the dosage was like ten times what it used to be and that's because the fleas were becoming resistant to carbaryl which is not as common, a carbamate insecticide is not as common for resistance to develop, but that does happen.
Some of the classes of insecticides or resistance happens quicker than others.
But, I can give you a list of some of the different modes of action that are out there.
And there's over 20.
- Well is it because these insects are reproducing so quickly and there's so many generations?
Is that sort of the key-- - Of course.
- To why resistance happens so quickly?
- That and, you know, if you kill 98% of the populations you think, well that's pretty good, but that two percent reproduces-- - Pretty quick.
- And probably most of their offspring are also resistant and then you can see how over a period of-- - Doesn't take long.
- Short period of time you can have all sorts of problems and many of these insects have multiple generations per year.
So that can really create a problem.
But, you know, a acetycholinesterase inhibitor is one, it inhibits, you know, causes of, basically a nerve gas.
It's a nerve gas that kills insects.
And that actually, these insecticides were developed from nerve gases that were developed back in the '30s and '40s or '20s and '30s for other uses, you know?
Back then.
But there's acetylcholine receptor antagonists, there's nicotine acetycholine receptor agonist.
- That's would be the nicatoids we're hearing about now?
- Right.
- That's what that is.
It targets the central nervous system.
- They're insect growth regulators that inhibit chitin and synthesis and there are-- - So that keep them young or something.
- They're too young to reproduce, you can't reproduce.
And so, it may not kill you, but it keeps you from reproducing which is important.
- That's pretty neat stuff.
- Molting disruptors, there are electron transport inhibitors, there's a lot of different products out there.
And the take home point from this is, don't continue to use the same insecticide.
I know when I was in the cattle business we would, for years and years and years cattle producers have used a back rub, the cows can go under and it rubs an insecticide on their back and it kills the critters.
But, very, very quickly I learned to use one type of product this year.
Next year, I completely switch to another.
I might use an organophosphate this year and then a pyrethrin next year.
- Rotate.
- You know rotate your classes to prevent resistance.
It's resistance management, trying to prevent creating a super critter.
- Shift totally your mode of action is what you're doing?
- Right.
You can do that, there are products out there that you'll notice on the shelf that have two different products in them.
They have two different modes of action in them.
You know, kind of be careful using those both out at the same time because the critter that survives that is resistant to two modes of action.
But fortunately we've got over 20, you know, we've got a lot that we can deal with.
- That's a lot to choose from.
- I don't think we're gonna have super bugs.
- I hope not.
- Any time soon.
- Now what about fungicides?
- Fungicides, the same thing, we found that, and that was probably the last organism that I've seen that's developed a resistance.
But even it's been out there for a while.
I remember even back in the '80s we were using benlate.
We were using a real common benomyl, a real common fungicide and it was starting not to work as well as it used to.
So they've switched the classes.
But there are strobilurins which is several of the real common heritage signas compus, are strobilurins which we have seen some fungal diseases develop a resistance to in the agricultural community.
Frogeye leaf spot in soybeans is an example.
But, so, you can add another class, a triazole with that and in the agricultural community, you usually don't completely switch to another because some of these fungicides have a lot of strength on several diseases, some of them have strength on other disease.
Then if you completely stop, you'll control this disease then you'll have another disease that'll wipe you out.
But in the agricultural community when fungal resistance is encountered, most of the time the farmers will have to use a product that's got multiple modes of action.
But, in your backyard for black spot control in roses, you know, you can go with Daconil, but there are several things that I-- Chlorothalonil.
- Chlorothalonil.
(indistinct conversation) - And that's a strobilurin, but Daconil is not.
Strobilurin, where's Daconil?
Chlorothalonil, it's a chloronitrile.
So it's a totally different.
Same thing with blight on tomatoes, Mancozeb and chlorothalonil are two fungicides and they're totally different classes.
Mancozeb is a dithane four junction pentatholon, or Mancozeb and they're in the M3 class.
Dithiocarbamate's and relatives.
And then Captan is another product, it stands alone.
It's in the M4 phthalimide group and-- But keep in mind, if it has, strobilurins, if it has strobin on the end of it's active ingredient, pyraclostrobin, azoxystrobin, or whatever, it's a strobi.
And just keep in mind, don't just stick with the same fungicide, mix it up if you can.
And that's why I read off all of those when I list a bunch of products that'll control the disease.
- That's your take home message so we appreciate that, Mr. D. [gentle country music] - When you clean your garden spot of all the old plant debris, and the soil gets fairly clear Well, you go back out there in a little while, a day or two, or even a week or two, and you've got thousands of tiny, little weed seedlings, like all of these right in here.
Thousands and thousands.
So, the easy way to do the weed control like, to take care of those, is just to rake your rake across the soil lightly, and it pulls hose little dudes up when they're really small.
This only works when they're really small.
And then, you can do that periodically through the winter, and what you're doing is you're forcing all these weed seeds to come up and destroying 'em.
So, you're gonna have less weed seed the next spring that's gonna come up in your soil.
And, to show you the difference this makes, this of course was raked.
This was not.
[gentle country music] Here's our Q&A session, and Dale you jump in there with us, alright?
- Yeah.
- Here's our first letter.
People are still writing letters and we have a picture that actually came with the letter.
It says, "Dear Chris, I planted these blackberries "in September of last year, the vines have really grown.
Should I let the canes grow or should I prune them back?"
This is Mr. Vonn in Lewisburg, Tennessee.
- That's a menacing question.
- Yes, it is.
- Well you know, blackberries are interesting critters.
Okay, they planted them this past spring?
- They planted them September of last year.
- September of last year.
So all of the canes produced this year were primocanes?
- Right.
- Called primocanes and they're strictly vegetative and so I'm sure he didn't have a lot of blackberries this year.
Now, the canes that come off the primocanes are floricanes, are the second year.
So canes are biannual, the roots are perennial on blackberries.
And so canes live two years.
First year the primocanes, second year the floricanes and the fruit are produced on the floricanes.
Yes, you can prune back.
- ]Yes.
- Probably a good idea to prune them back.
Most of the fruit are produced back toward the base of where the floricane comes out anyway.
So I would prune the floricanes back to 18, 20 inches.
And get 'em back and if you have erect types, erect blackberries, probably bring them down to 38 to 40 inches in height.
And you won't adversely effect your fruit production at all.
- Alright, Vonn, there you have it from Mr. D himself.
Will not effect your production.
Alright here's out next letter.
This is pretty neat, Dale, writing letters.
"Mr. Chris Cooper, my crape myrtle is at least 50 years old "and very large.
"It had a lot of dead limbs in it this spring.
"The winter must have been hard on it.
"It still bloomed this year on new limbs.
How and when should I prune my crape myrtle?"
This is Ms. Marian Blytheville, Arkansas.
So, Dale, what say you about that?
So when is the best time to prune your crape myrtle and how would you go about doing that?
- Well if you're, the nice thing about crape myrtles is they flower on new wood.
You can cut them all the way back to the ground and you still get flowers.
They're really tough.
You know, there's a whole movement Jason Reeves is part of.
- Yeah, "Stop the Chop!"
- And so, you know, crape myrtles do have wonderful forms and shapes, too.
So I like to prune a plant, if you plant a plant in the right place, you should be able to prune it to it's natural form.
And, so, I think prune a crape myrtle anytime your shears are sharp would be a good answer.
In the winter you can see the structure better.
But horticulturally I don't think there is a wrong time to prune a crape myrtle.
And, you know, I like to cut back anything that's bigger than, say, the size of a number two pencil.
Like when you were a kid, those big fat pencils.
I don't think they do anymore.
- Mechanical pencils.
- That's right, mechanical.
- So, anyway, or digital, I'm not sure.
So anyway, I hope that answered the question.
- Yeah, that answered the question.
And I'll tell you something else, anything that's crossed, anything that's diseased.
- Absolutely.
Dead, crossed, diseased, always.
- Get those out of there, you know, back to the nearest large branch of limb or back to the trunk itself.
- A lot of people like people like to limb 'em up too, take the suckers of the bottom, limb them up so you can see that beautiful trunk.
But we're having all the issues with the scale here.
Have to see what that's gonna do.
- We're gonna find out a lot more about crape myrtles here coming up real soon.
So I hope that answers your question.
Here's out next letter.
- All three, letters?
- All three, letters!
Look at that, college ruled paper, how about that?
"We have several nandina bushes, the tallest is six feet "and the shortest is about four and a half feet.
"How far back can we prune nandina bushes and when is the best time to do so?"
And this is Bill in Rossville, Tennessee.
Mr. Bill, we have Dale.
I think Dale can help us out with this one.
Prune back those nandina bushes.
- Do you want to?
- No, have at it.
- Nandina bushes tend to, they're natural habit is sort of very long and leggy and then they have this horizontal branching at the top.
The best way to prune a nandina is to go all the way down to the base and take out some of the canes.
- All the way down to the base?
- All the way down to the base.
You don't really hack them in the back, then they get real bushy at the top.
You want to keep that structure where they're very vertical and then horizontal.
That's kind of how large nandinas grow.
I would say late winter would be the best time to prune them.
You know, a lot of people are concerned if you cut something back hard now, that it won't have enough time to harden off good before it freezes.
And so that makes sense.
But I like to reach in and sort of thin those canes as well.
So reaching in and going down low is the best way to prune a nandina.
- Wow, down to the base.
- Kind of like blueberries, right?
Prune 'em at the back.
- Alright, so I hope that answers your question.
Alright, so here's our next viewer email.
"My tomatoes would not ripen this summer."
How about that?
"Now that we have had some cooler weather, "they are putting out lush green leaves and tons "of clusters that are just staying green.
"This is the first time this has happened.
"I grow them in pots every year.
Has this been a bad year for tomatoes?"
And this is Ms. Elizabeth in Pleasant View.
I thought this has been a pretty good year for tomatoes.
- It's been pretty tough.
- I think pollination when it's real hot, isn't that a problem?
- Well, you know, they will abort the buds when it's real hot, but you know, once we get to the temperatures that we have now, which are cooler, then they're gonna start reproducing like crazy.
But, I thought the tomato season's been pretty good.
Earlier on we had a lot of rain.
- Yeah, that was a big problem.
- Early on, but then you know, we kind of got, it was a little straight there with the weather and everybody I know, most of the farmers that are producing tomatoes was like, "Hey, it's been good, no problems."
- The optimal temperature for tomatoes to ripen is between 66 and 78 degrees.
That's the optimal temperature.
If temperature is above 85 degrees, tomatoes are not able to produce the pigments that will let it get ripe.
The lycopene, there's two of three different pigments that will cause it to change color.
So if you have sustained temperatures above 85 degrees, and we did.
- Night temperatures above 85!
- I mean sustained temperatures above 85 degrees, and we did even in my area, up in Lauderdale and Dyer County we had tomatoes that didn't get ripe.
- Wow.
- They just sat there on the plant and they stayed green and they didn't get ripe.
But, in the middle of the summer, yes.
And up until just a few weeks ago, tomatoes have really struggled in my area.
- In your area?
Okay and they've been fine here from what I heard from the farmers.
- I know Chris spent some time in Corvallis, Oregon.
- Yeah, I did.
- And it was the exception when you had a ripe tomato.
The year of the green tomato was pretty common.
- That's right.
- I guess it wasn't hot enough.
- That's right.
Alright, Dale, Mr. D, we're out of time.
- Good deal.
- Great, thanks for having us.
Fun.
- Remember, we love to hear from you.
Send us a email or letter.
The email address is familyplot@wkno.org And the mailing address is Family Plot, 7151 Cherry Farms Road, Cordova, Tennessee, 38016.
Or you can go online to FamilyPlotGarden.com.
That's all we have time for today, thanks for watching.
I'm Chris Cooper, be sure to join us next time for The Family Plot: Gardening in the Mid-South.
Be safe.
[upbeat country music] [acoustic guitar chords]
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