Dreaded iris borer

I see signs in the leaves just started a couple days back, first blooms opening a week ago.
The recommended preventative/killer is Cygon 2E-Dimethoate and I have some but the mixing label is gone.
I just hate those "booklets" on the containers that either stick together or fall off at the first sign of wet.

Anyway, I also have Borer-Miner Killer (Permethrin) which doesn't even list iris in its flower listing! figure that
Since I have 60 new rhizomes this year I want to get crackin on the pest.

So what do you all think?
Borer killer or Cygon 2E (and I need the "recipe"
Thanks much

Don't hve either of those as dreaded borer hasn't reached here yet. Don't know how many iris you have but try feeling down the leaf where you see a borer has gone in. You might find him still in the leaf and you can squash him inside if you feel him. If you can't find him, go right down to where the leaf joins the rhz. You can prob. find him and squash him there.

Just an idea.

Inanda

I'm so sorry that you are facing Iris Borer! We don't have them here thank goodness, but I'm sending you what looks like a pretty complete link.

http://ianrpubs.unl.edu/insects/g12.htm

I doubt if permethrin would have much effect against iris borers. For that matter, if you've already got bloom, it's probably too late for any of the systemic insecticides to work on borer larvae. Borers are only susceptible to systemic insecticides when they are small. Once they've been feeding for a while and gained some size, systemics won't kill them.

About all you can do at this point in the season is try to catch and kill as many borers as possible before they reach the rzs. Do this by squeezing each leaf between your thumb and forefinger, starting at the rhizome and working up toward the leaf tip. If you encounter a borer, you will feel the pop.

If the borers have already reached the rzs, your only option is to dig the affected plants and cut out the borers.

Early next spring, just as your irises are breaking dormancy and starting to grow, buy a bag of granular Bayer Season Long Advanced Lawn Grub Control with Merit and apply it to your irises. Water it in well. Merit is very effective against borers if it is applied early enough, and it is far less toxic to you, non-human animals, and the environment than Cygon.

Good luck!

Laurie

I have a question regarding iris borers. I'm in Vancouver, WA, and supposedly we don't have them here. What zones are they most common in? The reason I'm asking is that I had an iris this year that seemed to be getting a bloom, but then the bloom just stopped and the stalk became discolored. I cut the stalk off and looked inside where the bloom should have been. Inside a found a fat, white grub-like worm that was about 1 1/2 inches long. It had eaten most of the bloom and had started to chew into the stalk! I've never had this happen before and I don't know what to make of it. I checked the rhizome, and it seems to be unaffected. Can anyone give me some insight? Thanks!

This message was edited May 21, 2005 5:01 PM

I don't know if this was a borer. Hope you squashed it right away. The borer is on the east coast of both Canada and the US> Apparently it was found here in central Canada a few years ago but has not been seen since.

There is a great deal of info on the net.

http://www.irisgarden.org/borermain.html has good info and pictures.

Check the rest of your iris. Look at each leaf to see if you have damage on the edge of a leaf. Usually the borer enters the leaf, causing visible damage. Then it eats its way down the leaf to the rhz. growing larger and larger. It will enter the rhz. and eat away, till it exits into the soil and pupates.

If you see damage on a leaf, as if something was nibbling at it, feel the leaf and if a borer is in there, you can squash it inside the leaf, the way Laurie describes. above.
Cleanliness is VIP as the borer eggs overwinter on iris leaves. In the fall make sure all iris debris is cleaned up and garbaged - NEVER composted.

When receiving iris from anywhere, a good plan is to totally immerse the entire iris rhz and leaves in a mixture of Chlorox and water for at least 30 mins. Then rinse well before planting. I do this with lilium bulbs as well for the lily beetle. 2 parts chlorox to 8 parts water.

Another thing. If you find another grub in your iris, it might be a good idea to take it to your local Ag office so it can be identified.

Hopes this helps a bit.
Inanda

Actually, borers are a problem throughout the upper 2/3 of the Midwest and East in the U.S. You can see a map of their distribution here:

http://www.gardenshield.com/

That same site also links a pretty good article on borers at:

http://www.gardenshield.com/alert.htm

The bleach soak Inanda recommended is commonly used by iris gardeners to disinfect rzs before planting, but the mixture is typically 1 part bleach to 9 parts water. I'd be hesitant to use a stronger bleach solution on irises. Unfortunately, the bleach soak doesn't necessarily kill borer larvae, esp. those hiding deep within the plant tissues.

Laura, I don't know what sort of beastie was eating your iris stalk, but it doesn't sound like a borer to me. It is possible, though. Borer larvae start out as tiny whitish caterpillars with dark heads. As they feed and grow larger, they turn pinker and retain the dark heads. You can see pics of the various stages of borer development here:

http://www.worldiris.com/public_html/Borer_Sequence/Iris_Borer_seq.html

For your sake, I hope that's not what you're seeing in your garden.

Laurie

Thanks to both of you for your help! I don't think it was a borer that I found, because it was much whiter and didn't have a dark head. However, I do have something munching at my leaves and I did find that one grub, so maybe I have a problem of a different sort. I had really bad leaf spot this year (from massive amounts of rain!), so a good cleanup and spraying is in order anyway. Maybe it wouldn't hurt to use a bit of pesticide as well. If I find another grub, I'll take a picture of it and post it, as well as bring it in to be identified.

I've read of other folks in the rainy PNW having a lot of trouble with slugs and snails eating their irises. Perhaps some slug bait might help your situation.

Laurie

It's true. I have to put out TONS of slug bait every season, and they still eat at my plants!

I've dug out all of my iris in July - cut off the obviously infected parts and
soaked the rest in clorox water for several hours. The borer grubs float
out of the iris - eventually even the ones deep in the rhizomes start coming
out. My place had several beds of iris when I moved here - they were
seriously infected! I've been pretty good with the clean up and seem to
have kept the borer at bay. Those worms are really creapy though!
It kind of wigs me out to see them all floating around or tryng to get out of
the rhizomes.

Once they are all clear of borers, I rinse them off and set them to dry (outside)
for few hours or overnight. I've done this twice (once at my old house too)
and the iris came back just fine the next year.

Tam

After the bleach treatment you can leave them out for two days in hot sun to cure them. It's their dormant period in July anyhow. I moved 687 at one time, 2 years ago, and didn't get some replanted for a long time (shame on me) but they're ready to bloom now. The borers are disgusting! A different kind of disgusting than slugs and different from tomato hornworms! Yuk. The best part of the whole project is lily white nails and no compost thumbs anymore.

Flowerfrenzy (what a good name). Looking over my BC journal, found that weevils were really bad with my iris. I would go out at night anc catch them with a flashlight.

Finally did resort to spraying, some systemic but didn't write down the name. Maybe that is what you have.
Inanda

inanda~

Oh my gosh! We had a bug in WA last year that I'd never seen before. I looked up Weevils on the net, and guess what? That's the bug I saw a lot last year! The larvae look exactly like what I found inside my iris stalk as well! I think you've hit the nail on the head! Luckily, I have not seen that bug around anywhere this year, and I have found no more larvae. Thanks for your input!

Really happy it wasn't a borer. Glad it is finally IDed.

Now then. When you buy any lilum or iris from anywhere - particularly the east suppliers, please please soak in cholorox (javex so much easier to spell) before planting in yur garden. Just to be sure that you don't by mistake bring in the borer -- or the dread lily beetle.

Inanda who made up her first lily order of the year, to find that 5 yes FIVE that I wanted are already sold out.
!@#$%

I usually buy my irises from the NW because there are really great iris farms around here. However, I did buy a few harder to find ones from other places last year. I usually soak mine before planting, but I got lazy last year because I was pregnant. I guess I won't be lazy this year for sure!

So that's what those nasty, pink grubs are! I've been cutting them out of the rhizomes for about two years now. Have been doing what everyone and the books suggest and soaking in bleach, but they always come back. They only seem to affect the germans and versicolor, though, haven't seen any in the siberians.

Hi Cultivate weeds. If you check your iris religiously next spring, you can usually catch them before they hit the rhz. Depends of course on how many iris/how much time you have.

You want to try to get them before they reach the rhz., before they exit and pupate in the soil. You can get two batches per season. Ah me. Sibs do get them too. Pseudacorus in water seem to be the only ones safe from them. Guess they can't live under water.

Inanda

As soon as the weather calms down, I'll run out and start squeezing leaves! ("WHAT is she doing...?")

The most important part of any borer control program is a very thorough garden cleanup in late fall and again in early spring before temps reach 70 degrees (borer hatching temp). Borer eggs overwinter on old iris foliage and perhaps other plant debris, so getting it out of your garden (trash or burn, do NOT compost) will eliminate a large proportion of eggs before they have a chance to hatch in the spring.

Laurie

cultivateweeds: I dip them in clorox solution (10% or more) cutting the rhizomes apart and getting rid of any soft tissue and then letting them dry in the sun as one step forward. I change spots every few years because I believe the grubs stay in the soil (or their larvae). They are so disgusting!

Hi everybody~

I found another mysterious grub and took him in to be i.d.'d. Turns out it's a cutworm. The larvae are similar to that of a Weevil, but not quite the same. I guess they're a big problem here in the Pacific NW. I picked up some insecticide (systemic) that should wipe them out and prevent any further infestations.

Please keep us posted as to the success of the product! I'm sure we'd all like to know the name of it.

Thanks everyone for the suggestions. This just occurred to me, and it is worrisome...last summer I found a similar pink grub eating its way down the core of the thick, horizontal root of my bloodroot (Sanguinaria canadensis). I cut out the grub, dipped the rest of the root in fungicide and replanted it, but it died anyway. Has anyone heard of the iris borer jumping to other genuses? I'd never heard of anything attacking Sanguinaria...

Cultivate weeds.

Send your question to Prof. Del Grande at RI university. He is doing research on our little red non-friend.

I do know that they go to frittilaria but don't know about other species.
Inanda

inanda, do you have an e-mail address for him? Couldn't find him on the URI faculty site. Thanks!

go to the URI website and search for
bio control lab red lily beetle.

He and his team have been searching for something for this dread beetle for quite a few years. They are supported by many lily societies, as well as commercial companies.
Inanda

uh, I thought this was about the iris borer?

DuH. You are kerrect!!! Have no idea why I switched to lily beetle. Maybe because am having a talk about this on another thread and fergot which thread I was on. Of course, Rhode Island Uni isn't working on iris borer at all.

Major brain fart. Abject apologies.
Inanda

ROTFL multi-tasking! no prob, I dropped an e-mail to CT aggie station, they post that they are researching iris borer.

Hey, that is exciting news. Do they have a website with anything in particular of interest to us on it???
G