Hi, ! Glad you're here!..Arlyn

Hello from New England.

And from Kentucky!!

Thank you for the warm welcoming guys and gals!

It's great to know there are no borer issues in Cali....(yet).

I am starting to find more borers than I thought I had. I put down the Bayer granual stuff and it worked well in some areas but not others. I got rid of about 10 today as I move stuff around and did in three that had already wrapped themselves up for the winter.

Depending on when you put it down, and how much rain you have had, maybe it's "worn off" ?,,,Arlyn

Hello all. I just had to remove every single Iris on my property due to this borer. I had never, in my life, EVER had any problems with my landscaping, so when I decided to try and figure out why my Irises appeared to be dying, I was shocked to find this ugly critter and the destruction left in its wake (see attached - it used to be a thriving 28' x 3' bed of lavender irises). Frustrated, I dug up every single iris, regardless where it was planted, because of the sheer destruction of just one iris bed (I have four other locations on my property). I noticed only about a three foot long patch that had not yet been hacked, but I dug those up, too, for fear there was already initial damage done to the fans.

It's now August, and I realize this is my own fault for neglecting my landscaping to the point that this was my only option.

My beds are empty. What can I treat them with to prevent any pupae or residual eggs/larvae from surviving without their food source?

Harley, You are probably too late to treat them now, You could salvage some of the firm rhizomes after you check to make sure there are no borers in there. It's important to discard, as in burn or put in the trash the old leaves and infested rhizomes. After you re-plant, you may want to treat the new irises with a systemic product that kills them. I use a product by Beyer that is used to kill grubs in your lawns. You need to treat the areas where you are growing iris in the spring after you have a streach of weather above freezing for about 5 or 6 days. That's about April in my zone. Then each fall and spring, you will want to remove all of the dead leaves and burn or discard them, don't put them in the compost, as that's were the new crop of borers eggs are. Even with treatment, you may find one once in a while. Good luck!

Signs of borers: edges of leaves chewed ragged, frass [light color droppings] near the base, fans falling over, hole in base of fans and of course in rhizome.

My treatment: similar to Arlyn's but without the chemicals, dig rhizome, trash any leaves with smelly rot on them, carve out the bad portion of the rhizome, let it dry and skin over, treat with bleach or bleach cleanser to reduce the chance of bacterial rot setting in. The rhizome work can be done in the ground or with rhizome out of the ground. Any roots or rot goes out in trash or on a burn pile.

Irises are hardy; Arlyn has cut some up into small parts and 80% have grown the following season.

The type of soil makes no difference. It is the "crawling" portion of a life cycle of a moth which lays eggs on or near the plant. Poison in or on the plant can kill the critter in the crawling stage. Nematodes can reduce the population as well. A large infestation can kill an entire bed, as noted already in the thread. Removal of dead leaves and other matter around the plants limits the places the eggs can overwinter and is probably the best thing to do.

This critter was removed, rhizome treated and is doing fine at last check several weeks from the "botanical surgery."

And a welcome to the several newcomers to the iris forums!

Harley !I agree with Tom...sort of! Plant your iris...and if you want to use "chemical controls", do so. Any borers that have already "buttoned up' for the year WON'T be killed, but any "new" ones, chewing on the fans, will be. Then, next year, at about the time Tom mentioned, apply your chemical, according to directions. The stuff I use (same as Tom's, I think) lasts "about" 3 months....the more rain you have, the quicker it will be "used up"...so you will need to re-treat the area...I do it in mid-June. The product in the Bayer Long season Grub Control (and many other similar products) is trade named "merit", and is a systemic insecticide, meaning that any bug (or person, for that matter!) that chews on ANY part of that treated plant will be affected. I always find a few borers, no matter what I do, so you need to be vigilant for them! If you find him on the leaf...squish him, if he's already in the rhizome, follow Dave's advice. If you want to go "chemical free", beneficial nematodes and "squishing" are about your only options. The nematodes are kind of "pricey", but, so are chemicals. Most of the chemical controls have been linked to Colony Collapse Disorder, in honey bees. ( this is an issue that is heavily debated, and you can find tons of "pro", as well as "con" info on the net) I "keep bees"....,and I use chemical controls, following the instructions for their use, and using what *I* think are "common sense" rules...I drench the soil, not the plant, I apply when the bees aren't active, and I grow plenty of blooming flowers and plants that the bees find more to their "taste" (which are NOT treated with insecticides, herbicides, or fungicides). As was stated earlier, the borer isn't the big problem...it's the softrot entering the "wounded "area that's the biggest threat....so controlling the borer is step one to controlling rot. Good luck with your efforts!...............Arlyn

Good advice Arlyn. Being responsible in whatever we use to control the war on our irises is very important. Knowing about the chemical and acting to lessen its impact on desirable insects such as honeybees is a must.

Wow, never seen such total devastation an iris borer does. I have never had an iris borer here that I know of. I had one iris in an isolated area that had a couple V notch cuts on its leaves this spring so I dug it up a couple weeks later and checked it out. Never found anything in or on it. The iris is still growing well. Good info to know in case anyone ever has a problem, and the pros and cons of using chemical control.

I should have added that if a person is using any of the systemic insecticides, DON'T use them close to ANY food crop !! The iris I grow that live on the edge of the veggie garden DON'T get systemic, although I DO spray them with "BT" (thuricide) a few times a season ( but not during bloom time). These iris get "checked"for borer more than the others, and so far, I have seen no evidence of borer in those beds. I may try nematodes in these beds, as that would be a "food safe" control.....although if I let the veggie garden go completely over to iris.. ...Arlyn

Really Arlyn? BT? For borers? I have to think about this.......................

The effectiveness would be limited to the time the borer is "on the leaf". In order to "get the disease", the caterpillar would have to either ingest, or touch the "BT" ( I think). Also, the rain, or even a heavy dew, would tend to wash the BT from the leaf, although the residue left in the "leaf -fold"or whatever you call it, would be hard to wash off, and that's the area the borer travels on his way down the leaf. I don't spray it while ( or just before) bloom, because it's another thing that could be carried back to the hive, by the bees..and while it doesn't affect adult insects, anything still in the larval stage (worm) could be affected. I generally spray the iris at the same time I spray my "kale" crops...every 2-3 days, or so. One thing about the white, cabbage butterflies, that lay the eggs on the kale crops is, they are active in the daytime, so when you see them, you know you need to start sprying, and , by the number of them you see, you can gauge "how big' your problem is (or might be). The Moth that "is' the iris borer operates at night, or at least in low-light situations, and is sort of "camo" in color, so they can sneak up on you !! Still (IMHO) the best thing to do is inspect your plants for signs of damage, and keep the beds cleaned up! ............Arlyn

Some people also burn off the dead leaves as a way of preventing the borers from hatching. I've never tried that method. I think Kent does that.

I thought Arlyn did that.

I had an accidental burn-off last year -- but I don't think that counts.

I do, sometimes....kills insects, destroys the left over fugal spores (leaf spot), and I think it helps with some weed seeds, as well. The one bed I "burnt" last fall had the least problem with leaf spot this year, but, it also was the bed that was dug, and reset this year...so maybe the leaf spot just hadn't really "kicked in" yet?! I think this fall I'll burn again, at least some of the areas...the re bloomer bed needs dug and divided next year, and has a terrible leaf spot trouble this year...so I'm thinking I'll burn it off, for sure.................Arlyn

We would not be allowed to burn here.

Not here either. No yard waste burning in the city limits.