Dreaded Iris Borer

I have been out in the gardens digging and dividing iris for the last two days. I have iris borer and I'm trying to get them under control and out of the gardens before they eat their way back into the ground. I'm bagging up the bad stuff and sending it off to the landfill, and I'm bleaching the good stuff. Now, is there something I should do to the soil they came out of? Is it safe to replant there or should I move everything to new iris beds? Thanks!

Diann

ps. There is this strange satisfaction I get out of watching the borer go pop... gross, but pleasing to the thought.

Short of sifting your soil to try to remove any migrating or pupating larvae, there's really nothing you can do to eliminate borers that may be in the soil. You can replant in new beds as far away from the infested beds as possible, but that still won't prevent borer moths from flying over to the new beds and laying eggs when they emerge later this summer or early fall.

Laurie

Laurie, thanks, that is kind of what I was thinking, too.

Hopefully, I've gotten the majority of borers now, before they've moved back into the soil. Every rhizome that I've dug up that was rotten had a borer in it. So, maybe I'll catch a break with this.

Has anyone tried the parasitic nematodes? I also understand that Iris Borers are some what cannibalistic. So, there really shouldn't be more than one per rhizome??

I have three more spots with Iris that I have to dig, and those will happen tomorrow, and then hopefully once I get things bleached and dried, we can replant. Thanks.

Diann

I think it is impossible to correct the situation by getting all the borers out. Even if you did this, from somewhere else, not your property, a borer moth can fly to your iris beds and start over again.
The best way to 'control' the borer is to clean well all the debris and dead leaves around the iris either in the late Fall or early Spring. Use an application of Merit in the early Spring if you want. Some people even burn away dead leaves from the rhizomes in early Spring. Point is: get those eggs out before they hatch. If you do these things, even one of them, you should reduce the borer population dramatically.
Laetitia

It may be impossible to correct the situration by getting all the borers out, but it's better than letting them feed their full and then go on and pupate. Beside, I'm not silly enough to think I'll get them all, I'm just shooting for the majority.

I was just wondering if there is something I can treat the soil with to help my odds. I think it's too late for Merit, correct?

I live in the middle of 10 acres so, if I can get this under control now, I'm hoping that I have a better year next year. I've had Iris for 14 years and the last two years have been the only times I've noticed this problem, and trust me, you notice it if you have it. :)

It rained last night so digging today in my last bed should be a bit easier...

Thanks!

Applying Merit now would be a waste of money and time. Merit is only effective against hatchling borer larvae. The larvae are far too large by this time in the season to be affected by Merit.

Thanks Laurie, that's what I figured. The last bed is now done. I saved only the pristine ones and everything else is bagged and ready to go to the landfill. The really nasty part is over. Now, to bleach and figure out where I want to replant. I have a couple spots in mind, dryer areas, more air circulation.

Thanks Laurie and Laetitia for all the advice. I really do appreciate it. :)

Diann

Ticker, Funny you should ask about the nematodes. I was just reading up on these, some are good and some are bad. Apparently the good ones do help in getting rid of borers. We don't get borers here so I haven't tried it myself. I was also reading that you could sprinkle your irises with a powder cleanser like ajax for any bacteria problems. I'm wondering why it , or would it help get rid of borers also. I can't imagine anything wanting to bite into ajax.

I think the Ajax and Comet are supposed help with the bacterial rot bearded Iris can get. I believe you are supposed to cut out the effected area and then sprinkle the cleanser on the open wound of the plant. This is all done while the plant is still in the ground, if it's out of the ground you might as well use the bleach solution. I don't think it will have any effect on borers, but I don't know that for sure.

Nematodes still fascinate me. I will have to do some more reading on them.

Just to be clear, no one here is saying to sprinkle your whole bed with Ajax. I haven't researched this, but of hand it sounds like a very bad thing to do.

Ajax does not kill borers (unfortunately). Nothing does once they start chewing and you notice them. All you can do is hunt them down and kill them by hand. Don't sprinkle your bed with Ajax for any reason. That is just a waste of good Ajax. Just use it on open wounds of the iris.
Laetitia

Iowa must be God's Country for Iris Borers! I am also in the middle of a battle to the death. Like you, I dug all of my iris that looked infested early, to get rid of the worms before they got to the ground. They are drying in my garage now, and I am going to pot them up and store in a window in the garage until after egg laying season is over. Then store the pots with straw in a corral outdoors over winter. Some I will also plant outdoors close together, to be divided in the spring, and enclose in insect barrier mesh - to keep the moths off of the plants.
The ones that were free of borers are planted in their own bed, in regimented rows, further apart so that I can keep everything clean and inspected. I am hoping that once I get rid of most of the borers I can maintain control with inspection and removal of dead leaves. Merit is supposed to be bad for borers, but I couldn't get myself to buy any. Might also be bad for other things, you know? So far my garden is totally organic and I would like to keep it that way.
Oh, I also dug up and threw away several clumps of not-bearded yellow flags that have been here from who knows how many centuries. They reseed terribly if they aren't deadheaded, and never seemed to be bothered by borers, but after digging I found evidence that the borers do have a community there; probably migrating to the tastier beardeds.
Now I just have my siberian iris to deal with......

Caitlinsgarden, From what I understand (from this forum and reading the bag) the active ingredient in Merit is the same stuff a person uses for fleas on your cat of dog... I'm don't have a prohibition against using chemicals in my gardens, I just don't seem to remember to use them in a timely fashion.. I'm creating a new bed and I'm thinking that most of the iris will go there...

Good luck fighting your Iris Borer battles! :)

Diann

Good grief, I found three more patches of Iris I didn't realize I had... and both were in plain site... I'll be digging them and hunting down borers that they might have...

I know what you mean, Ticker. From now on all of my iris are going in their own clean bed where I can keep an eye on them!

Ticker, my chickens eat them. I know it isn't a solution for everyone, but you did mention living on ten acres. When I lift iris to renovate a bed, I scatter some feed in the bed to lure the girls there, and they'll spend a hour or so digging and munching on......something. (I have given a chicken a rhizome with a borer peeking out, and it went right for it, so I'm pretty sure they're on the menu. I've also seen them catch the moths in flight in the spring.) I'm in an area where borers are a problem, I have thousands of iris, and I have only the most minimal damage; maybe one or two clumps a year. BC (before chickens) I would have extensive problems. I don't use any chemicals.

katie

That's very interesting, but I had chickens once, and not again!
I don't believe the iris borer moths fly in spring - only in late fall?

No, chickens aren't an option for me. I like my chicken fried or bbq'd. There were three wild chickens at the acreage when we bought it. The use to root in the trees at night. The rooster would start crowing about 4:30 in the morning right out side the bedroom window. I contemplated blowing him out of the tree with the 12 gauge, but I never did. They were old and just kind of died off one by one.

Caitlensgarde:
You are right. The iris borer moth is only around in the Fall. It has a short life. I think it only hatches to breed then lay more eggs then die.
Foul creatures!
Laetitia

Do we know when in the fall it is active?

Yes, I will look it up. I think Sept / Oct

They found me!!
This is my very first year with iris and I'm already haunted by the iris borer. I don't think I'm going to be buying more. Yesterday, I discovered that all of the beds I have planted iris in have been infiltrated!
So now I'm on a mission and came here to learn more. I already scared! :-)

I'm going out now to start digging them up.
First, I dig them. and inspect them. Is this right?
Then I cut off the damaged part. Right?
Then soak them in bleach water. For how long?
Then rinse and let dry.

Since I don't have a new bed to plant them in, I don't really know how to proceed.
Ticker, did you discover anything else about treating the soil?

Please let me know what else I can do.
THanks,
LoraB.

Nope, all I learned is that it won't do any good to treat the soil till next spring. I was over at my in-laws yesterday weeding and cleaning up her gardens and I dug all her Iris and yeah, there are Iris borer there too. However, with hers the worst infestation was in the Siberian Iris. So, I just trashed all of it. I put back smaller amounts of iris in the beds and put in more daylily.

I've come to the conclusion that Iris Borer is a serious nuisance, but won't take out all the iris. One just must be vigilant about watching the signs for them, digging them out and trashing the bad stuff in a garbage bag and sending it off to the land fill. Next year I will be treating my grounds for grub control.

My father in law kept a couple iris borer to see if they make good fishing bait... yuck. LOL

Diann

This message was edited Jul 22, 2007 9:55 PM

What would you use to treat the soil? I've not had borers before but any info is good to have. I've got to dig up my old iris bed full of NOIDS so I can plant all my new named iris so who knows what I might find:)

Next spring I'll use the Bayer grub control for lawns..... I don't know the proper name of it off the top of my head...

Ticker:
Make sure the product has the chemical imidacloprid in it. Also called Merit. Sometimes they come out with products called 'grub control' but it has a different chemical in it.
Laetitia

Thanks Laetitia, that's the stuff I'm after. :)

Diann