Help - Torrential Monsoons All Summer, Iris Rot Noted

We normally get a fair amount of rain and have high humidity so I have learned to plant my iris high with the backs exposed. I even have some planted on a slope. This has worked well for me - until this year. After a severe drought in early spring, we have been inundated with relentless torrents of rain almost daily. Flood watches and warnings are a daily occurrence now. Parts of my backyard garden have been waterlogged for quite some time. Often when I look at my 10dayforcast, I'm lucky to see a 'sun' icon on even 1 day. Many days we get 3-4 inches or more in one day.

Yesterday when I was out (between showers) cleaning up some beds I was shocked and devastated to find areas of rot on some of my well established iris growing on a slope in the front yard. The front yard itself is on an incline such that it drains rapidly and is more likely to be dry than wet. The bed with the iris is on an additional slope within the front yard. The iris bed is under/around a dwarf sweet bay magnolia. Leaves from the magnolia had fallen onto the bed forming a sort of natural mulch in and around the iris. Despite the grade, the impromptu mulch appeared to be holding water and causing the iris to rot.

I pulled all of the leaves and debris away from the iris and pulled back the soil enough to insure that the tops of the rhizomes were all well exposed. I removed any rotted leaves and small rhizomes, cut (with my trowel) rotted portions of larger rhizomes back to healthy tissue. Is there anything else that I can/should do to try to save them? (We are experiencing a rare sunny day today, but otherwise the rains continue.) Should I dig them up and let them dry out a bit, then replant?

Thanks for any help you can provide.

I'm so sorry!!! I don't know what to tell you but I sure hope someone comes along soon to advise you.

Judy

I think you did everything right, make sure you don't put the diseased rhizomes in your compost and be sure to sterilize your trowel. Keep and eye on them and they should be fine, if not you can always dig them up later.

Hi Judy,

Thanks for the emotional support. It really is difficult to see those large well established rhizomes rotting.

Thanks, mittsy,

By 'dig them up later', do you mean that under adverse circumstances I can do that at any time - I though I could only do that in Fall. It rarely gets very cold here though. We might see an over night low of 28F once or twice in late Jan or early Feb, but it will usually be back up in the 60-70 range by the next day. I put the diseased parts in the trash.

Thanks a lot for the help. I knew if anyone could help it would be you folks over her in the Iris Forum.

In my considered opinion (imco) I would either buy a bottle of Listerine -the real stuff not a knockoff - and pour full strength over each cut where you have scraped all the rot off, back to clean white raw-potato looking rhizomes. (Hint from irislover this one)
OR
Rub very firmly, ajax, bon ami, comet - whatever you use in your kitchen. Rub it very firmly into each cut. It works. And good luck.

inanda

inanda,

Thank you! This is one of things I was wondering about, whether there was something I could put on them to help heal the cut areas and minimize the possibility of infections there. (As much as it broke my heart, I did cut back to the crisp white 'potato' like flesh.) I had considered putting medicated, anti-fungal powder on them as I've read this works well on some bulbs, but then I thought better of that idea fearing it might 'burn' the rhizomes and exacerbate the problem. That's when I decided the right thing to do was to ask you folks here on the Iris Forum - and get it right.

Thanks very much.

What about the bleach dunk? Iris are very hardy and will survive,( not flourish) with all kinds of neglect. When we divide them we remove all dirt and give bleach dunk, let dry before replanting or trading.

i don't think what you are seeing is "rot". I think it is just the normal spent mushy rhizome pieces on normal established iris. We had all of our "floodings" this spring. I divided a large bed this summer and didn't have any rot. The rot i'm talking about is bacterial rot.
I don't think flooding is going to cause that. as far as the flood damage if there is will probably appear in the fans first. But they will eventually drop those ugly fans and grow new ones. Bacterial rot is suppose to have a fetid smell to it. I think you are just fine cutler. besides it would be too soon to have that much rot this quickly.

mittsy -- Thanks. I haven't decided whether to dig them up yet, but will definitely keep that in mind. This is all very good info. I have found them to be very rugged with respect to almost everything except excessive water.

Len123,

I didn't know about this:

Now that you mention it, I believe the mushy stuff I called "rot" was only on large multi-part established rhizomes. I had no idea that this might be 'normal'. I need to look that up and do some reading. I didn't notice an odor on any of the material I cut away or see any rotten or mushy foliage/fans. The fans are still green and look fine. Hmm.

I recall (from the news) that you guys had a lot of major flooding in some areas. We had only shallow flooding in localized areas. I had some standing water in the backyard, but the iris in the front yard (which are on a berm atop a slope) are too high up to go under water without some serious flooding. Let's just say that by the time they go under the house will be floating away. However, since late spring, we've had almost constant rain, not after noon showers, but daily storms with torrential downpours. (In one day, my wheelbarrow filled to within a few inches of the top. The kid's wading pool went from empty to overflowing in one day.) For most of the summer this has continued for 7-9 out of every 10 days. Where we normally get 1-2 inches of rain per month, one month we had 15! Even though we didn't flood outright like some areas I was thinking the months of constant relentless rain, coupled with 80-100% humidity daily (which is easing up a bit now) and moisture held in place by fallen leaves, etc might have caused problems. It has rained so much for so long that I can't mow the lawn because the ground can't hold up under the weight of the mower & my gardeners/landscapers can't get the trimming/edging/maintenance done in the front yard because it's always raining. It's a mess here, but if our current forecast holds up we are looking at 4 or 5 consecutive sunny days for a change. Yay!

Thanks for the info. I'll have to look into this new info.

i had mushy iris rhizomes turning up all summer in my clumps. No stench of rot. I thought it first was iris damaged by the hard week of 18 degrees in April. Then torrential rains hit and more mushy iris showed up weeks later. Not in low areas--distributed all over my gardens. My iris are all usually high and dry.

Hi Wanda,

So what do you make of this? Are you thinking that this is some new 'disease'? Or that it was rot, implying that rot doesn't always exude the characteristic odor? Hope you didn't loose many of your iris due to this strange malady.

I checked mine just this past week to find that all of the problems seemed to have cleared up except on one rhizome which had rot on one far corner, the rest of the rhizome having already been converted to an empty shell.

Any chance that now you have removed the soft mushy tissue from your iris, you could put them into pots with fresh compost so they get a chance off recovery for next year, to replant them in the position they were already flooded in, will just cause the tubers to continue to rot even more,
when you do have to divide old large clumps of tubers, there should never be any rot on them but just old tired out tuberous growth that needs removed and the outer new tubers replanted. it would also be good to cut down the foliage by half to give the plants less foliage to try support over the winter if in pots. keep an eye on the potted tubers incase there is any further mushy rot setting in, they dont need to be kept indoors, but would be helped if place in sheltered part and not so wet till your weather improves, I feel so sad for you, but even over here in UK we have had too much rain and my garden has been so sad and wet this year, even my greenhouse plants didnt get enough sun all summer and the plants have not done as well as normal. good luck. WeeNel.

I used listerine extensively on a bunch of guest we had that started to rot just before the tour for our regional of the 30+ that were noted with rot I saved all in place except three and one of those three put up a new shoot from what I though was a dead rhizome and scheduled for elimination after the show.
:)
A

I don't think it is any new disease, just a rough year. Too much cold & rain weakens the rhizomes. Most of the rhizomes dried out after I removed the mushy ones. And the strong ones spent their energy replicating instead of blooming. With decent weather, next spring should be a boom year.

How are those irises doing, scutler?

Hi girl,

Sorry I'm a bit late in responding. I'll have to go out there tomorrow and recheck them. Then I'll let you know for sure. The last time I checked them they were doing much better. Only one rhizome had a mushy area on one edge. (I removed that of course and retreated that one.) All of the others (many of which I'd treated earlier) were all firm and healthy. I noticed that the one rhizome that had continued to accrue mushy areas was in a 'dip' (despite being on a slope), so I dug that one up, filled in the shallow hole and replanted it. I haven't pulled the soil/mulch back up around the rhizomes yet. It hasn't been very cold here so I figured they would be better off with the exposure. Also, we've had a week now without rain. I'm sure that has also helped the iris.

The past few weeks we've been working a lot of overtime trying to meet a project deadline, so I haven't had much time for the irises just recently.

Thanks so much for asking! :-)

I've had similar experiences, believing it was rot when it wasn't. Good luck with them and please post photos in the spring.

You know, I got so busy with everything that I forgot to come back with an update. I'm starting to think I may have jumped the gun so to speak on this issue. I don't normally look at my iris in fall. By that time I'm usually too exhausted from summer chores and too busy with fall planting, so for all i know, Len123 may be right, and my iris may go through the same process every year. Perhaps what I saw was actually normal.

When I was doing the cleanup, cutting off mushy stuff that i thought was diseased, etc., I picked up the last remains of a one year old variegated iris, my only variegated one, Zebra Blush. It was all dried up, shrivelled and clearly no longer viable. With great reluctance, I tossed the dead rhizome with label still attached into the garbage and resolved to order another one ASAP. It had done well in it's 1st year and was planted high on a slope so I really couldn't imagine why it had succumbed. Then a few weeks ago while out doing yard work I noticed the 'stubble' of new variegated foliage peaking out of the ground in the spot where the 'dead' plant used to be. It wasn't dead at all. It's very much alive. Today the new foliage is about 6-8in high. Was the 'dead', dried up piece that I tossed out just the 'spent' rhizome that is part of a natural cycle of growth?

At any rate, I see new foliage popping up all over the place in that iris patch so it looks as though most of them are going to be fine. Thanks so much for your help, Everyone!

pirl, I sure will post pics in spring! Thanks!

Such terrific news, scutler! Your post is a real day brightener.

Great news, scutler! I would love to see some new growth right now, but I have a few months to go. My first iris bloom last year was May 12.

Glad that your irises are coming back. We once threw some extra iris thinnings into a galvanized bucket and forgot to compost them. They came up in the bucket the next spring so we gave them to a neighbor.

scuttler, if the spent rhizome had any food left at all in it it would have sent out new fans so it could start making more food and storing in new rhizomes.I think you will have more than you will know what to do with in a few years!

I was glad to see this thread-I had just planted about 20 rhizomes this last year and this past week had a TON of rain, then the temps dropped right away...I was afraid that I would get rot on them and was almost in tears-this thread has given me hope!! Thanks!!

fairy1004, if everything else in your garden dies, then you might want to check and see about your iris's. At least the rhizomous kind. It was so wet last spring that i lost a lot of lily bulbs and iris bulbs i had planted, but the iris done just fine. they had some spotted fans, but when they turn completely brown they just dump them and start growing new fans.

OK, that does make me feel better too-like I said I was just afraid that all of the water, then it freezing with them still in it would cause rot....

Thanks!!