From the studios of Lehigh Valley Public Media in Bethlehem, PA, it is time for another plant-killing episode, of chemical free horticultural hijinks You Bet Your Garden.

I'm your host, Mike McGrath.

Everybody knows that the roots of a black walnut tree are tomato kryptonite.

But did you know that sunflowers can have the same effect?

On today's show we'll discuss four bad actors in the plant vs plant survival struggle.

Otherwise, potential guests are busy burning their bird feeders.

So we will be helping with your telecommunicated questions, comments, tips, tricks, suggestions and impishly inappropriate implications.

So keep your eyes and ears right here, true believers, because it's all coming up faster than garlic mustard in your mushroom patch.

Right after this.

Support for You Bet Your Garden is provided by the Espoma company, offering a complete selection of natural organic plant foods and potting soils.

More information about Espoma and the Espoma natural gardening community can be found at...

Welcome back to another thrilling episode of You Bet Your Garden from the studios of Lehigh Valley Public Media in Bethlehem, PA.

I am still your host, Mike McGrath, probably because the people upstairs don't actually watch the show.

And we've got a bowl full of goodies for you guys today.

What does that mean?

We're going to talk about allelopathic plants.

There's more of them out there than you know.

And if your plants are dying, you could be finding out why.

Plus, of course, lots of your fabulous phone call questions, comments, tips, tricks, etc.

But first, I finally found as I was cleaning out my overcrowded office, a book that I've been claiming existed to you for years and years.

You probably didn't believe me, but now it's true.

The book is Microcosmos and it is a companion volume to a fabulous film that was released around 1996, and it has these amazing close-up photos of the most interesting insects.

So here's the cover.

I'm going to go to where I've got these ugly little pieces of paper in there, and I'm going to tell you the pictures that you'll see.

Oh, my goodness.

This is a close-up of a damsel fly, and what I like most about it is it slightly resembles the head of the fly in the classic '50s movie with Vincent Price, and the remake wasn't half as good.

Is that a shock to you?

It's not a shock to me.

Next up, we have very different eyes.

These look like the glasses people buy for New Year's Eve.

This is the eyes of a gadfly.

And they are just, I mean, there's so much more diversity in their world than in ours.

It's like, it's impossible.

Did I drop one out already.

Oh.

First, this is a double pager here, the first you've heard me talk about green lace wings, which are a marvelous beneficial insect.

Here are there eggs in the wild, dangling on thin strings, almost looking like party lights or street lights.

But if you see these, love them, because green lace wings are the ultimate eater of aphids, much more so than ladybugs.

The other picture is a dragonfly next to its molt, meaning that this is the final version of this metamorphosis next to the old casing like we see with cicadas.

And dragonflies are so cute to begin with.

It's amazing, it's amazing.

Chrysalis of the Peacock Butterfly.

Which opens up a whole bunch of questions.

Can we see a picture of the butterfly?

No, no, they don't have that.

But you can look it up.

But this is like something from Tutankhamen's tomb.

It's amazing, the diversity in the water.

Oh, all right.

Get the children out of the room right now, OK?

Because this is a photo of what looks like 100,000 buff tip caterpillars devouring a willow leaf.

And if this doesn't make you squirm, you've never yelled in fright at a scary movie.

And finally, a praying mantis in, quote, spectral position.

I imagine it's called spectral because the next thing the bug knows, it'll be saying hello to its maker.

That invites really interesting questions as well.

The book is called Microcosmos.

It was published by the fabulous art book company, Stewart, Tabori & Chang.

And if you can find a copy, grab it.

If you can find multiple copies, give them out as gifts.

I'm so glad to have found it.

I'm almost down, I'm almost down to the floor in my office.

So let's keep hoping that I will find even more treasures as opposed to old potato chip wrappers.

Phone calls, do we take phone calls on this show?

I was just going to pick... OK, OK, OK. Jim, welcome to You Bet Your Garden.

- I'm glad to be here.

Thank you for listening to me.

- Oh, well, we're glad to have you here, Jim, where are you?

- I'm in Lebanon, Tennessee, near Nashville.

- Very good.

Well, what can we do for Jim near Nashville?

- Well, I have a first year crop of asparagus and I'm getting mixed advice on what to do this fall, when to cut it back and how to cover it after I cut it back and just wanted to get some ideas on it.

- OK, did you harvest any of it this year?

- No, I did not.

- Good man.

- Planted the roots.

- Good man, - But the spears did come up?

- Yes, they're taller than I am.

- Yes, OK, so they have formed what we call their fronds.

Those beautiful fan-like things.

And how do the fronds look?

Are they still green?

Are they turning color?

- They're still green.

We haven't had a frost.

We're just now starting to get some cool days in the 40s.

- OK, great, because, you know, they absorb the solar energy that's going to give you a good crop, a little bit of a good crop beginning next year and then every year thereafter for 20 or 30 years.

So right now, again, the hardest thing for a gardener to do is do nothing.

So you're just going to let those fronds stand until you've had a couple of hard frosts.

Now, do you know what you planted?

Did you plant one of the all male varieties and old heirloom?

- I wish I remembered the two varieties, a purple variety, it's what was recommended.

- OK, let the fronds stick.

Did you have any asparagus beetles?

- No, I haven't seen the insects.

- OK, great.

They're very distinctive, they're very colorful.

All right.

Well, after you have a couple of good hard frosts, then you can cut them down.

Don't go too low.

You know, leave a good sized stub coming up out of the ground.

And then, you know, I would just chop the fronds up a little bit and use those to mulch the beds.

If you want to remove them, mulch the beds with an inch or two shredded leaves.

- OK. Is that in line...?

- Yeah, because, you know, because one of the things I had been told was to cover them with compost, but you said just cover them with mulch?

- Um, you know, compost wouldn't be a bad idea.

Do you have the compost available?

- I've got a pretty good bit of compost.

- OK, yeah, I'm going to yield to that other advice and say two inches of compost, that'll start feeding them as soon as the soil warms up in the spring.

- Mm hmm.

OK. - OK. -and I understand it's important to keep the beds weeded, right?

Oh, yeah.

Yeah.

Weeds are the biggest enemy of asparagus, which I think is maybe why some people like to remove the fronds because they can get in the bed once it freezes without damaging the new spears.

And then, yes, you want to pull any weeds you see.

But I like the idea of doing a little wait till the frost, wait till the freeze actually, cut down your fronds.

And if you're going to use them, put the compost down first and then lay the fronds on top.

- OK. - All right?

- OK. - All right, I'll be over for some cream of asparagus soup in three years.

- We'll be looking for you.

- All right, Jim, you take care, sir.

- Thank you.

Bye.

Ernie, welcome to You Bet Your Garden.

- Well, good morning and how are you today?

- I am just ducky, thanks for asking.

And where is Ernie?

- I am in northern California in a city called Redding, California.

- I've been up there.

So what's up in Redding?

- Well, when I moved into this house in 1998, there was a beautiful mimosa tree in the front yard about 20 feet from the house.

And the tree died in 2004.

But I've got roots that I can't kill.

- Suckers coming up out of the ground?

- Yes.

- Yeah.

It can look like Mickey's Beanstalk.

Not Mickey's Beanstalk - broom, in The Sorcerer's Apprentice.

You know, they just seem to replicate like mad.

How large of an area is being affected?

- Well, actually, my whole front area, which I would say is a half an acre.

- And you got suckers coming up all over it?

= I've got suckers coming up on both sides of the house and up against the house and my other flower beds.

- Flower beds are going to be tricky, I got to be honest with you there.

For the front yard, which I presume is grass?

- Yes.

- I think there we have to go rope a dope.

Because when you cut the grass, you'd cut these things down, right?

- Yeah, but they're back.

- Yeah, but... How long have they been coming up?

How many years?

- Since about 15 years.

But they never develop anything, they just keep being a wooden stake upside down?

- They grow into, they're trying to grow into trees and the areas in the yard.

- OK, so the most important thing is you do not allow them to grow a single leaf.

Make sure you cut them down.

There are advanced weed whackers that use chains or hard ♪plastic pieces instead of...

Instead of the spool of plastic wire and I think, well, they're not called brush cutters, but there is a hyped up lawnmower that is for cutting brush.

And as soon as you see these things, you want to keep knocking them down, because if they grow leaves, then they collect solar energy and, you know, then, you know, they'll continue to grow.

They'll continue to send up these, these suckers.

- That's what my problem is, is they have grown leaves.

- Yes.

Yes.

So we have to stop that.

You could also...

There is an organic herbicide whose active ingredient is iron.

And it is, yeah, it's a broadleaf herbicide, so if you wanted to try it... ..once the leaves are formed, you could spray it with this iron spray, doesn't hurt anything, it's actually good for your soil.

And see if you can make it unhappy by killing the leaves.

The plant expends a lot of energy to push those leaves out.

So if you spray them with iron, I think that would have a good effect, although nothing is going to be better than cutting them down as soon as you see them.

They're too tough for a regular lawnmower?

- Oh, yeah, they are.

- Yeah, so I think you're going to... - Or a trimmer.

I use a high wheel trimmer.

- High wheel trimmer.

I'm not sure what I know.

Those are like a regular weed eater, except they're on wheels.

- Oh, OK. - They have... - Just use regular trimmer line?

- Yes.

- I think you have to investigate getting a weed whacker that works with metal chains or... - OK, with chains.

- Or hard plastic blades.

- OK, thank you.

- Yeah, and the ones in the flower bed, I would protect the flowers, you know, lay down newspaper or tarp or something and spray those heavily as soon as they put on leaves with the iron solution.

And that way you won't be killing the flowers underneath.

To me, this, if it were I, I would be out there with my favorite gardening tool, a machete, and I would be taking out my anger on these beasts.

- Oh, yeah.

- But those plants are famous for it, but keep up with it for a season or two and I think you'll see really good results.

They'll start coming up soon.

- Well, thank you so much for your help.

- I hope it was helpful.

You'll let me know, right?

- Yes, it was.

Yes, I will.

Thank you so much.

- Thank you.

Bye-bye.

As promised, it is time for the Question of the Week, which we're calling... Helen in New River, Arizona writes...

I would dig a house in the ground.

Now before I lurch into attempting to answer this intriguing question, I should explain the concept of chilling hours.

Most fruit trees and cane fruits, like raspberries, require a certain amount of cold weather to flower and produce fruit.

The standard for this, quote, chilling is below 45 degrees Fahrenheit.

Doesn't have to freeze, just below 45.

Low chill fruits, which are specially bred for warm areas, can generally get by with around 300 hours of this kind of weather.

I would go into more detail, but I might not ever come up for air.

And that means it's bullet point time.

Begin with eucalyptus.

Research has shown that due to their allelopathic effect, eucalyptus trees quickly take over when they're introduced into an area with oak trees.

Experiments using an aqueous solution to plant parts showed that, quote, eucalyptus water inhibited the growth of many important crops, seeds as well, or just plain killed them outright.

Black walnut, the poster child for allelopathic plants.

Every single part of the tree - leaves, fruit bark, etc - inhibits or just kills a wide range of plants.

But the roots contain the most of the active ingredient, and these roots typically have a spread three times the size of the canopy.

As many gardeners know all too well, tomatoes and related crops are most severely affected.

We move on to garlic mustard.

The headline at nature.org tells it all - invasive, destructive and edible.

This common weed flies under most people's radar, but it is a very bad actor.

Also known as Poor Man's Garlic, hedge garlic, garlic root and Jack by the Hedge.

It has a garlic smell when the leaves are crushed.

Who's Jack?

It is a biennial, a plant that takes two years to produce flowers, with small white blooms appearing the second spring.

It takes down other plants in two ways.

One, it spreads its seed earlier than native plants.

It was brought here from Europe to be an erosion preventer, which turned out to be a really bad idea as it prevents the growth of the later blooming plants that actually do help prevent erosion.

And two, its root system interferes with the fungal network underground that helps native trees and other plants thrive.

Although technically edible, you must, as with pokeweed, harvest the young shoots before they build up toxins, in this case, cyanide.

What a charming plant!

Learn how to recognize it and pull it slowly out of wet ground before it flowers and sets seed.

Experts say you will see positive results of such pulling within a year as all of those good plants get to come back.

Sunflowers - got your attention there, didn't we?

Although people love feeding birds in the summer for human enjoyment, the result is a triple no-no.

One, feeding seeds to birds in the summer is unnecessary and potentially damaging to the birds as they lose interest in the abundant natural resources they have relied upon for centuries and lose the food-finding instinct and the exercise it provides.

Yeah, yeah.

You like to watch the cute little birdies, don't you?

Even if it leads to their extinction?

Your entertainment is not worth the loss of a single species.

End of sermon.

Two, spilled seat of any kind attracts mice, rats, voles, raccoons, rabbits, deer and anything else you lured to your landscape with the promise of endless food.

And to the point of today's topic, sunflower seed hulls are allelopathic.

Or haven't you noticed that nothing grows underneath your feeder?

Birds need fresh water from you in the summer and suet in cages in the winter.

That's it.

And that's just a small sample of a very long list.

Allelopathy is an adaption that leads to a species' success.

Inhibiting the growth or just plain killing other plants is an excellent way for that plant family to survive, and many plants have acquired this adaption.

Always remember that the world outside our windows is Darwin, not Disney.

It is a life and death struggle to survive every day.

And it is not for us to change the odds by human interventions like feeding birds in the summer.

Well, that sure was some good information about killer plants now, wasn't it?

Luckily, you can read this important article over at your leisure, because the question of the week appears in print at the Gardens Alive website.

Just click the link for the Question of the Week at our website, which is still and will forever be YouBetYourGarden.org Gardens Alive supports the Question of the Week and you will always, always find the latest Question of the Week at the Gardens Alive website unless something goes wrong.

You Bet Your Garden is a half-hour public television show, an hour-long public radio show and podcast, all produced and delivered to you weekly by Lehigh Valley Public Media in Bethlehem, PA. Our radio show is distributed by PRX, the Public Radio Exchange.

You Bet Your Garden was created by Mike McGrath.

Mike McGrath was created when he thought he had gained superpowers, challenged Dr Doom to do battle, woke up in the microverse and had to be rescued by Antman.

Yikes!

My producer is threatening to plant black walnuts in my tomato patch if I don't get out of the studio.

We must be out of time.

But you can call us any time at... Or send us your email, your tired, your poor, your wretched refuse teeming towards our garden shore.

Please include your location.

You'll find all of this contact information, plus answers to hundreds of your garden questions, audio of this show, video of this show, audio and video of recent shows and links to our internationally renowned podcast, It's all at our bursting at the seams website.

I'm your host, Mike McGrath.

And I'll be outside shredding the leaves and soaking up the wonderful weather of autumn until I see you again next week.