Will do this thread backward since is more accurate to post the pics then a description.
This is a first year clump which had an odd looking fan. Tugged at the fan and it came
off cleanly at the edge of the rz. The rz was soft and mushy back about an inch from
where the fan was attached. Dug it and pics follow.
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#2 End of the rz.
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#3 Clump after first washing with the hose.
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#4 Good strong root system.
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#5 Closeup of the rot.
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#6 Adjacent rz otherwise healthy.
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#7 Mother rz could be salvaged & replanted.
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#8 Hosed out rot.
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#9 Closeup of the otherwise good rz.
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#10 Another.
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#11 Possibility of borer.
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#12 Does not appear to be borers.
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#13
Great photos and explanations gardenrose. I think alot of people will be able to learn alot about rot from those pictures.
Thanks for sharing and explaining everything to the people that are fairly new to irises.
Great Post! Happy Gardening, Marian
That's exactly what I wanted to see and needed to know! I've had 4 plants do this so far in Sept. (the stinky white gunk is so ugly.) My only problem is that there's not enough time to replant them. I did replant 2 next to the house and sheltered areas and will try to cover them well when the first frost comes. I think I will also experiment and pot a couple to bring home to NE over winter.
Thank you!!!
P.S. So the reason's for them getting root rot is ??? Because I haven't connected the dots yet on the ones that have developed it. I also need to get some 'borax' to kind of sterilize the soil where we dig it up?
P.P.S. Here is a double rainbow across the road from us this evening. Beautiful!
The common wisdom is planting too close together, too much nitrogen fertilizer,
lack of direct sun and too much moisture are the primary causes of both crown
and bacterial soft rot.
Once the spores are in the soil, they can last for years. I also have my own
theory that, once the clump is infected, the succeeding rhizomes will be "carriers"
and will be more prone to infections. I just destroyed 35 or 40 really nice noids
for that reason. Had severe leaf spot and probably some minor crown rot. My
primary bed will remain idle at least until next planting time or possibly another
year.
Another theory of mine is diseased soil mixes and humus/compost from the
garden centers. I see green weeds, stones,partially rotted bark and other
kinds of junk in the stuff I buy.
Another source of grief is swapping plants which have not been thoroughly
cleaned and sterilized. Small amounts of soil can harbor all sorts of critters
which may not be a problem at the source but the conditions are right for
explosive growth in your garden.
Don't want to sound like a windbag but sometimes there are no simple answers.
For ready reference, without searching the internet, I highly recommend a
book by William Shear 'The Gardener's Iris Book' for all but the most expert
iris gardeners. Contains 90% of all you need to know in order to enjoy
growing irises.
Wow! I can really understand what you are saying about 'when a clump is infected'. It has been so hard to get them back
to a healthy plant, once it has had any kind of 'owie'. As I've mentioned before, when my Iris have gotten frostbite, 2 out of 3 times, they can't come back. That's why I am digging them up and replanting in an outside area. I still take care of them but let God decided.
Thank you again oldgardenrose. I'll check out Amazon tomorrow for Shear's book.
If you have cleaned up the plant & disinfected them, you might try to pot them & sink pots in the ground for the winter. Have soil even with the top of the pot so will not collect freeing water. the shear book is excellent.
In order to clear up any questions about the first pic, I had originally planted this
temp bed last summer using a lot of the MG potting soil. About 2 weeks ago,
I cut the tops and flushed the excess soil away from the rhizomes in order for
the new babies to see some sunlight and grow before cold weather. That is
the reason for the short foliage. Must have been a good move because they
popped up like mushrooms.
Excellent pictures. Although I don't dig up the plant if I find rot. I figure the existing healthy roots and plants don't need the additional shock of trying to get reestablished. I clean out the rot, remove most of the soil around the rotted area so the air can get to it. And apply liberal amounts of Comet with bleach and reapply every time the ground gets damp until I see new growth. Fortunately I don't have too much trouble with rot and have only completely lost a few using that method.
In this instance, there were 3 or 4 clumps of the same iris (one of my oldies) and
it is no great loss if the two nice rz's I saved croak. I will move them to a spot
never planted with irises and give them a chance. I poured the bleach/water mix
into the hole from where they were dug after the soaking. A generous dose of
comet would probably work as well. Next summer they will all need to be dug
and sorted since the temp bed irises are planted too close to each other.
OMGosh!!! I just discovered what I think is rot. The iris were in great shape all summer through 100* in full 8+ hrs. of sun. I watered several times a week. A week and a half ago I added cotton boll compost and now I discover complete fans rotten at the base where they meet the rhizome. I've never seen this in my garden before now. Too much water is NOT the problem. Too much crowding is NOT the problem. I think something UGLY came in with the compost. What should I do first? Then what else? This plant is Anxious TB which has been very healthy for 2 1/2 years.
Post a pic of the clump and rz if you can. With a little extra work, some of it
can be slavaged if it it an important cultivar. Otherwise, dig it and dispose of
it. Check the rest of the bed for rot. If it was due to the compost, you can
be assured it will spread.
You amaze me, Oldgardenrose! Your knowledge of Iris should earn you a Dr. degree. Was this passed down to you or did you learn it through the years? I really appreciate every post you've made since I joined DG. TY
The only other thing I can think of was some 8-12-4 granular fertilizer that I sprinkled around in that bed. Would too much fertilizer in one spot cause this? Cotton boll compost is a favorite of iris growers in our club. They have hundreds of iris planted in it. Could I be the "lucky one" to get this? I dug the decaying iris clump out and set it aside to deal with later.
Look carefully on the leaves for a watery appearance, sometimes in streaks
and on others a solid discoloration. You can't miss it. I had that on some that
appeared completely healthy but the large, green leaves would come off with just
a twisting tug. They would be 50% or more brown or decayed at the crown.
Some say high nitrogen fertilizer causes extra large and lush leaf growth which
encourages rot but I cannot verify that with my experiences. I would look at
too much moisture even though you may be in a dry area. Several times a week
sounds like away too much water. Dormant irises need very little water but, if
water were the issue, you should have more than just one problem.
One thing I found is the advice to cut the bloom stalks after the bloom cycle is
over was exactly correct. The small vertical leaves and side bud junctions trap
water and causes the stem to rot quickly all the way down to the rhizome. This
would encourage crown rot or soft rot.
Thanks for the compliment Husker but I have no special training or lifetime of
growing irises. I fell in love with irises when I was a child. They were the old
purple, fragrant irises everyone had. Now, after growing the modern ones
with all their colors and ruffles, I am slowly getting back to appreciate the
oldies no one seems to want. Being retired, I finally have time to indulge
myself in collecting some of the heirloom types, as I call them.
This message was edited Sep 30, 2009 11:02 PM
