Sunday, July 26, 2009

Boring Irises


Did that title draw you in? Did you think to yourself, "Irises, boring?? How can that be?" Well, it's not what you think. I love Irises and to me, they're anything but boring. I do like some better than others, but they each have their endearing qualities, not the least of which is their colors and they way they're dispersed on the blooms.

But I'm not the only one who loves Irises.

This year, I'm waging all-out war on a not-so-little pest called Macronoctua onusta - Iris borer. I suspected them last year, but hadn't actually found one. This year, a couple of my Irises needed dividing, so I dug them up and it was then that I came face-to-face with the worm.

In years past, I recalled pulling center leaves out of the fans because they'd turned yellow. They came out easily and I did suspect that something was causing this, but it didn't happen often and it didn't seem to be harming the Iris a whole lot, so I didn't do anything. Therein lies my grave mistake.


The borer lays eggs in the leaves, where they hibernate all winter. In the spring, they hatch and the caterpillars (much too nice of a word for these disgusting things) work their way down the leaves into the rhizomes, where they gorge themselves on the heart of your Irises. The result is a mushy rhizome and usually death of that particular part of an Iris clump.
And what's worse, they like Siberian and Japanese Irises too, as well as Blackberry Lilies (Belamcanda chinensis). Ask me how I know.

That's the Reader's Digest version of the Iris borer story. For a great detailed tutorial of what to do about this problem, visit
The Renegade Gardener's page, Iris Borer Alert!



Tonight, I found yet another Iris that's been attacked by the borer. My 'Edith Wolford' had a fan lying on the ground, so I investigated and found a mushy rhizome. I dug it up and there it was - the Queen Mother of all borers:


It was two inches long and a disgusting shade of flesh-colored pink. The previous ones I'd found were smaller and white. I suspect the rest of the plant is infected, so when I have more time this week, I'll dig the entire thing up (as I did the others that were infected) and check them.


I called Romie out to the driveway to see what I'd found and he took one look at it and sighed, "It's always something..." Yes, it is, and while this shows the unpleasant side of gardening, I like to remember its better side:

'Edith Wolford'


'Princess Caroline de Monaco'


Unknown cultivar


'Red at Night'


'Immortality'



Helen's Iris


20 comments:

Lisa at Greenbow said...

I've seen the damage but never the culprit. I know they are here too. I guess I ought to get out there and get after them. Sigh...

Kylee from Our Little Acre said...

Lisa ~ We put it off because we'd rather stay oblivious to the obvious. There's nothing pleasant about dealing with Iris borers. I lost 'Enchanted One' to borers last year. I'm certain that's what did it in and I fear 'Edith Wolford' is going to go that way this year. Luckily, that one is easy to come by and I would definitely replace it if it comes to that. If I'd only known better earlier, I probably wouldn't have the infestation I have now. :-(

patientgardener said...

Goodness, I havent heard of the Iris borer. I do hope it doesnt appear here in the UK

GardenJoy4Me said...

Hi Kylee .. I was hoping Siberian iris might escape this bad guy .. I just put some in this year .. but now I have to face reality like I had to with the dreaded thug Japanese beetle .. eeuuuwww !

Janet said...

Oh Kylee, I hope you don't lose more! I think I lost a whole bed of purple pass-a-long irises from a friend. Seemed like it happened over night. Maybe I wasn't paying attention. Most disappointing.

Tatyana said...

How could he?!!! Kill him!
Kylee, the images of your garden are just charming. I love all of them, but especially the one with the bird feeder. Would make a gorgeous card.

Phillip said...

I love the clump of Princess Caroline de Monaco next to the bird feeder. Beautiful shots!

Kim and Victoria said...

Ick!!!!!!!!!!
It IS always something, isn't it? I love our iris and would hate, hate, hate to see some worm eating them to death.
Your irises are just lovely by they way.

Monica the Garden Faerie said...

Actually, I knew what the title was leading to... my friend had those borers, too. Thankfully (knock wood) I haven't had them. I too love irises!

Autumn Belle said...

It is very heartbreaking to see beautiful blooms eaten up by disgusting worms. The irises are so lovely, especially the blue and white ones and what interesting names they have.

jodi (bloomingwriter) said...

Oh, Kylee, I'm sorry you're being 'bored' with irises! I have had them here and consequently don't bother much with irises anymore. As Romey says, 'it's always something!' This is the year of much wet here in Nova Scotia so any borers would have to be able to swim, I think.

Patsy Bell said...

Well as I scrolled down the page, every Iris, I said That's a beautiful Iris and that's my favorite." It would be hard to have too many iris.

What really stands out is your beautiful landscape design in the Red At Night photo.

Sylvana said...

I love your irises. I think I have the same problem and will have to check out the info that you linked. I have all the variety that they like!

Carri Stokes said...

Yuck! I don't think I've ever come across one of those- but if I do, I will be sure to smash it with a shovel!

Connie said...

Eeeeewwww...gross is right. Love that Princess iris next to your birdhouse, what a lovely scene.

Muum said...

yurrgh, that was a gross borer. I'll check my irises, I thought there would be more signs in the foliage. :(

Cindy, My Corner of Katy said...

What an ugly and insidious creature! A pox upon them all! Those iris are just gorgeous. I do wish we could grow Bearded Iris here but we don't get enough cold weather for them to bloom.

Kara said...

I blogged about the same thing a week or so ago!

http://karaveihl.blogspot.com/2009/07/its-that-time-of-year-again-sort-of.html

I have just about had it with irises here. One website I read said to get the Bayer season long grub control and in the spring sprinkle a teaspoon over the iris clump. So.... I hate to use chemicals, but that will be my last ditch effort come spring.

PrairieGarden-Liane said...

I had to dig up my iris tubers last weekend for the same reason....have to wonder if they got my blackberry lilies because they did not do well this year. Totally depressing!

VW said...

I have read up on these pests before, and it sounds like they are currently confined to the eastern parts of the US. Hopefully they'll move slowly so my garden in Washington won't be afflicted for a few decades!
But it's always something here, too.

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