Oh, I'm so sorry.

We don't have them here (yet) so I can't help you, but I recall reading something about a bleach water treatment that works.

Good luck, and someone will respond with a better answer soon.

Renee

I found the thread, here it is.

Here is a link that might be useful: Iris Forum Discussion on Borer Treatments

I'm another N. Illinois gardener who has iris borers - first time ever. Unfortunately, I had no previous knowledge about these things until this week and when I went out this morning to dig up the rhizomes to investigte, it was too late. I've had to dispose of all of mine.

I've read the other linked thread and have a question - about the soil. Can I plant something else (non-iris) in this spot NOW without treating the soil? If I want to replant iris, should I do the Merit treatment NOW and replant right away? Or should I do the Merit treatment from now into fall and then replant iris next spring?

This year's blooming iris were wonderful - best ever. I'd love to have iris again, but I want to make sure I'm doing it right.

Thanks in advance for your help.

WOW ... hosenemesis... I hope you see this big big THANK YOU for finding that old thread from 2006 and posting it.

"book smart" is good... but when you learn from everyones experiences shared, its so much better!

and of course, thanks westy1941 for posting the Q

today I'll be giving my 4 small iris beds a good examination to aviod this problem.

If you find borers just kill them and cut all the rot away. Then dip in a 10% bleach solution. The Merit will only work in early spring before or as soon as they hatch. The little hole on the bottom are where old roots have rotted off. Borers make hole 1/4 " in diameter. They should be over 1" long now.

Ther is no reason to throw everything away. If you do nothing most of your iris will survive. All except you favorite. :-) You can do things to control them. Good fall and spring clean up works better than any thing. Remove all dead leaves and weeds, anything dried out. That is what they lay their eggs on.
Photo of borers and their eggs.

Mike G

Here is a link that might be useful: Borer eggs

Thanks for posting the pics, Mike, but I nearly threw up. Seriously it's good to know what you're looking for. I can't find the darn things - only the mess they made. I think I found a spot where they've laid eggs but I thought this was only in the Spring...does this egg laying go on all year? I've cleaned up the beds and am in the process of digging ALL of them and will be soaking in bleach/water soon. Thanks to everyone....I will be saving a fortune in gorgeous iris.

Westy

Mine were a soggy rotten mess and the borers and iris are gone. Mom in law is going to split hers again and I'll get more of the same, saving a fortune, too. Thanks for all the info - I wish I hadn't needed it!

Eggs are laid only in the fall. However the nasty things do not all hatch at the same time. It has been a very bad year for borer in the Northeast. I am finding big fat borers and tiny little newborn borers all in the same iris patch. Unfortunately they are so hard to kill now except manually. I sprayed every rhizome with merit in the spring, and still I have a bumper crop of borer. The opened bottle of merit was 3 years old. I wonder if it has a shelf life, but I am disposing of what is left and buying new merit next year.
Anyone have that experience?
I have never seen a borer egg except in Mike's picture. What is it they are attached to? A dead leaf? Are they almost microscopic in size?

I, too, had a difficult time determining exactly what those eggs were stuck to. And I haven't been able to find an actual WHOLE borer - I saw the head of one (it moved) and freaked out so I threw the whole iris away! I don't have the intestinal fortitude to take care of them 'manually'. All the posts have been soooo helpful! Thank you so much and especially for the thread from the past, hosenemesis, and the pics from Mike!

Westy

Oh, westy1941, I wish I lived nearby. I'd enjoy crushing those little buggers with my bare fingers.

It looks like the eggs are laid in large numbers on the dead leaf, and they are big enough to be seen with the naked eye (unless you are my age and don't have your cheaters).

Renee

I just love to kill borer! and I am the kind of person who takes most insects out of the house and lets them go, because I cannot bear to kill things I findinside who should be outside. Even spiders!
However there are two exceptions:
1) mosquitoes - because they attack me and
2) borers - because they kill my iris
I am sure there are other things I would kill, such as Japanese beetles and deer ticks but there are not alot of these kinds of things around.
I just love to decapitate their little red heads when I catch them. hehehe!

I started on another bed today and this time when I saw the brown icky spots lower on the leaves I opened one (it wasn't a leaf, but the bottom of a stem I think because I could 'open' it - there was a space down the middle like it was a flat tube. And I split it open and there was a bunch of horrible-looking junk inside - I'm going to take a magnifying glass out there tomorrow (with my cheaters on) because I don't think it's eggs but what is it? Is it just the 'deposits' the borers make as they eat their way through? It can be scraped off...it's slimy but looks like wet sand plus slime all the way down - like six inches of it. But I didn't see the borer....is it inside the rhizome? And what is the squishy slimy rhizome about? The ends of some of them are orange like a sweet potato and gooey.

Westy

CHECK THIS OUT
http://www.irisgarden.org

The photo of the iris borer eggs were taken on a MTB leaf. I had about 10 iris borer pupa in an aquarium with a screen top. They turned into moths, then bred and laid the eggs. I had three sets of eggs. How do I know they bred? some of the eggs are white milky looking. These are bad the translucent one are viable. They are small #6 buckshot in size. Only laid in fall.

Mike G