I had a borer war several years ago and ended up digging and dumpstering most of my irises. You can't imagine how many borers I found. I have some survivors however, and they have been doing good. Haven't seen any more borers. Do I dare to order more, or just keep what I have. What a question, huh?

caitlinsgarden said: I had a borer war several years ago and ended up digging and dumpstering most of my irises. You can't imagine how many borers I found. I have some survivors however, and they have been doing good. Haven't seen any more borers. Do I dare to order more, or just keep what I have. What a question, huh?

You just need to understand it's a war, not a battle.

Last year, my borer infestation was the worst I ever had. I had to dig up a lot. Soak rhizomes in bleach/water, sift the soil. Replant...

I threw each borer into the pond for the catfish. ... I'm not petty. Well. A little. But I can't see killing them when the fish can eat them.

I'm applying helpful nematodes. I've already done it before bloom season this year. I'll be doing it again soon.

Borers suck.
But don't give up. I thought I'd lose a few last year that survived. I'm impressed at how well these ladies survived with a little help.

Yeah, if you garden east of the Rockies, and have irises....you are gonna' have borers, sooner, or later! Some varieties seem a bit more resistant than others...or, at least can tolerate them a bit better, but *some* sort of "borer control' is going to be needed.

I wonder why borers have never spread west of the Rockies. I would think with people moving around some would get imported into the western states. Of course, I am very grateful that hasn't happened.

I have wondered that, too, Andrea. I think it's a good thing that when swapping, we examine the rhizomes carefully as well as giving them a bleach bath.

I sometimes wonder whether the soil west of the Rockies has something in it that their pupae can't tolerate. Volcanic ash from ages old eruptions? Nemotodes that we don't have in the east? Salts (gypsum etc.) eroding out of the Rockies Range.

DaisyDo said: I have wondered that, too, Andrea. I think it's a good thing that when swapping, we examine the rhizomes carefully as well as giving them a bleach bath.

I sometimes wonder whether the soil west of the Rockies has something in it that their pupae can't tolerate. Volcanic ash from ages old eruptions? Nemotodes that we don't have in the east? Salts (gypsum etc.) eroding out of the Rockies Range.

I wonder about this too. Going to look into this. What exactly is the cut off line for borer/non borer territory?

People who live just east and west of the Rockies should tell us whether you have borer or not. Maybe with this kind of input we can find the dividing line, which actually might or might not be the actual continenal divide.

DaisyDo said: People who live just east and west of the Rockies should tell us whether you have borer or not. Maybe with this kind of input we can find the dividing line, which actually might or might not be the actual continenal divide.

The "common wisdom" or "folk wisdom" as I've understood it, was the Rockies. I don't know if I've seen any WC folks talking about borer problems on the forums.

But here in the midwest, in southern Ohio, we definitely do.

DaisyDo said: People who live just east and west of the Rockies should tell us whether you have borer or not. Maybe with this kind of input we can find the dividing line, which actually might or might not be the actual continenal divide.

Yes please post! East of the Rockies would be Denver and Boulder . I would be interested in hearing from these folks!

I second everything said here. It's a war requiring constant vigilance. I too use nematodes but nematodes are a control not a nuclear bomb - some may escape so you'll have to keep a watchful eye. I know exactly what you went through - 2 years ago I had to dig up every iris in my garden, all 150 or so.

MamaFan said: You just need to understand it's a war, not a battle.

Last year, my borer infestation was the worst I ever had. I had to dig up a lot. Soak rhizomes in bleach/water, sift the soil. Replant...

I threw each borer into the pond for the catfish. ... I'm not petty. Well. A little. But I can't see killing them when the fish can eat them.

I'm applying helpful nematodes. I've already done it before bloom season this year. I'll be doing it again soon.

Borers suck.
But don't give up. I thought I'd lose a few last year that survived. I'm impressed at how well these ladies survived with a little help.

Moths fly from one garden to the next. So in the East you are never really rid of them.

But how far can they fly ? Our neighbors are not near us and they don't grow irises. I think my borers were here when we moved in - 50 years ago! I didn't know what they were at first but my fans kept falling over.

Are you absolutely certain you've gotten every single borer? And none will fly in from other areas? I've read that a single female iris borer can lay 1000 eggs.

I think that's why we can feel like we've won the battle, but not the war.

That sounds like a terrible curse for anyone who grows irises!

It is, Evelyn, especially here in the Chesapeake area where we are not allowed to use the pesticides that are effective against borers.
I must remember to apply nematodes again about the time the boreres return to he soil to pupate. Probably in August. Does anyone know for certain when that would be in the area between 7a and 6b. We are right on the margin between those two zones. I'm afraid that if I put out the nematodes too early they will die for lack of borers in the soil to feed upon. The borers would still be inaccessible, hidden away deep in the rhizomes. On the other hand, once they form their pupal cases, can the nematodes easily penetrate those shells?

It seems there are many kinds of Nematodes, some eat bacteria, some plant matter, and some feed on animal matter such as fly larvae or I assume the baby borers. So I guess one needs to be careful that you don't get the wrong kind. I don't think that they would starve waiting just for the iris borers. Here's an interesting article if you're interested.
https://www.ecologycenter.us/m...

Thanks, Tom.