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vajeff

New to iris - help needed

vajeff
12 years ago

Sorry in advance for the long post and many questions, but these iris are starting to drive me mad. I don't know how people do it...

I received some iris last year. They were planted during the summer... after sitting around for a few weeks (oops!), but did surprisingly well. One bloomed this year, and the rest bulked up quite a bit. However, several had to be moved this summer, and that's when problems and questions started to pop up.

Let's start from the beginning this year... Several iris had to be moved to make room for other plants. They were dug up, and I noticed that the base of the foliage was very plump yet the part of the rhizome that was under the dirt (and leaves/pine straw/etc.) hadn't grown at all. I decided to replant with some of the rhizome exposed. However, months later I noticed cavities forming on the rhizomes. No noticable discoloration on the leaves... at least no more than the few usual that shrivel up on the sides. I came to the conclusion that voles or some rodent was munching on them. A month ago I checked them again, and those cavities, which I initially thought were bite marks were huge hollow caverns - some large enough to cut the rhizome in half... and yet, the iris are still growing as if nothing ever happened.

Now, it's time to plant the fall flowers and whatnot. While browsing around, deadheading a few mums that got pretty ugly from all the rain, I noticed an awful sad looking iris. I pulled out some bad leaves, and sure enough a perfectly green one came out. Needless to say, that iris is rotting (and with a terrible smell too). I decided to dig all of them up and relocate. They grew a little too large for that spot anyway... poor daffodils wouldn't be visible behind them, and I couldn't dig those up due to all the tough azalea roots. Anyway, these iris were originally planted mostly under the dirt and had mulch over them. And, surprise surprise, they have giant cavities in them too... all except one. One even broke in half because the center was completely hollow. It's a shame the best of them (a single rhizome had 6+ babies sprouting off it) were the ones to both be eaten and rotted.

So... all that brings me to these questions:

1. Are any of these iris salvageable? If so, what do I need to do? A soak in bleach? A bit of surgical precision with the rotting ones? How do I keep water from collecting in the iris with pot holes in them? Will they eventually fill in?

2. What is causing these odd holes? I'm sure it's not animals now. I did notice chewed spots on the sides of leaves, so I'm thinking iris borers. However, they're bubbles in the rhizome... no tunneling from the foliage part. I was under the impression that borers burrowed down through the foliage and into the rhizome. Oddly enough, the holes are only in the sections of the rhizome that were exposed above the ground. I did notice vast amounts of "rolly pollies" in and around these holes. Could they be eating my iris? Ugh, those things creep me out!

3. Is it true what I've read about iris blooming the next year if they have 5-6 leaves? I was, to say the least, a bit put off this year when only one iris bloomed. I was hoping to find out what varieties I received... one was said to possibly be a blue and smells of grapes.

4. How should they be planted? Somewhat exposed? Slightly covered? On top of the soil?

5. Should the damage be iris borer damage, are there any systemic poisons available that would do the trick?

I love iris, but I'm almost to the point of tossing every last one out to make room for something more... newbie friendly and low maintenance. Any help would be great! Please!

Comments (4)

  • iris_gal
    12 years ago
    last modified: 9 years ago

    Those holes sound like what pocket gophers did to mine! They are salvageable if they haven't rotted. Those holes will not fill in. Cut away the damaged part. A 20 min. soak in a 10% bleach-90 % water solution is done then, followed by drying overnight in a dry place. Or Comet cleansing powder may be spread over the cut area if the iris is staying in place. Don't worry about the old withered mother rhizome - she dies after producing babies (sometimes called "toes"). The bad news is your pest will attack again. And it sounds as tho you have more than one pest.

    Bearded iris rhizome-tops do like to sun bathe. When a rhizome is damaged (from a trowel or an animal) it is susceptible to bacterial soft rot (the stinky smell). Rotten ones are goners.

    New bearded rhizomes often take 2-3 years to establish & bloom. Depends upon the vigor of the cultivar. 6 leaves is not a guarantee.

    Read what Schreiner's has to say about bearded iris care - they touch on borer info. Or do a search on "borer" on this site to read what others have done.

    Here is a link that might be useful: http://www.schreinersgardens.com/about_iris.shtml

  • cecily
    12 years ago
    last modified: 9 years ago

    Hi Jeff, I'm in Prince William county. With the unusual amount of rain that we've had, about a third of my iris have rotted. Mine are planted with the entire rhizome above the soil (I have heavy clay) and the bed they are in is elevated for drainage. But they rotted anyway... its just been a really wet year.
    I also have vole damage since we live close to a wooded area. In August/Sept of every year, I spray the rhizomes with a product called Mole & Vole Stopper (ordered online). I also spray the whole bed. I repeat the spray every two weeks until frost. Yeah, its extra work but my rebloomers are sending up buds now.
    Don't toss your iris but relocate them to an area with full sun and don't give them any supplemental water during the growing season. Keep them away from shrubs or bushy perenials and the vole problem should diminish.

  • vajeff
    Original Author
    12 years ago
    last modified: 9 years ago

    That's the first I've heard about the Comet powder. I'm definitely going to take note of that.

    It's a shame the rotting one has to be thrown out. I'm guessing there is no way to save the "toes" or any rhizomes connected to the rotted parent?

    I'm really hoping it isn't voles or moles attacking my iris. I'm almost tempted to put out a couple of traps and see what happens... I just don't want to catch a stray cat or squirrel. I've read something somewhere about hardware cloth to keep animal pests out of pots and whatnot. Could that be wrapped loosely around the rhizomes to deter them?

    I'm sorry to hear about your loss, cecily. We have heavy clay soil too and it's been a constant fight to grow anything like bulbs, rhizomes, or tubers. Ours is a pain to work with. It gets so... cakey and dense when moist. The recent week of rain only made things worse (and right after I started a new lawn in the backyard!). I've definitely learned the importance of raised beds this year.

    I didn't think about relocating away from bushes. They're planted near azaleas, and I have noticed odd tunneling in the soil around those. I'm going to take your suggestion and move them away from anyting that might act as a haven for the pests. Thanks!

    A friend has one of those devices that gives off a high pitched buzz and it seemed to work until he stopped (and the moles came back with a vengeance). I got one a couple days ago and will give it a try, and should it not work, I'll definitely give the Mole & Vole Stopper a try.

    Thank you for the advice! I've decided to give the iris another shot, so fingers crossed.

    Jeff

  • hosenemesis
    12 years ago
    last modified: 9 years ago

    Jeff, you can save the sections that are not rotted. Just cut away the rotted part and dust the cut end with Comet or dip it in 10% bleach water. When you cut into the rotted rhizome, you will be able to see the discoloration and keep slicing off pieces until it is all white.

    Any daughter rhizomes that do not have the rot can be left in place if you like, just cut out the rotted mother rhizome carefully. I like to dig out the infected soil and put new soil in and replant them, just to be sure.

    Renee

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