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Mar 18, 2018 9:19 PM CST
Name: Timothy
eastern oregon (Zone 7b)
Bulbs Region: United States of America Plant and/or Seed Trader Enjoys or suffers hot summers Salvias Region: Pacific Northwest
Peonies Region: Oregon Irises Hybridizer Herbs Dahlias
Ordinarily, the dry South Eastern Columbia Basin of Washington/NE Oregon is an ideal place to grow iris. Fairly fertile soil, just adequate rainfall, and little to no leaf spot or soft rot. **BUT** there is the spectre of Botrytis Convoluta that can make annoying to occasionally serious inroads to plantings and iris stock.
Of course, the beastie has a infuriating predilection for the central fan followed by the odorless collapse of the central rhizome. A gray fuzzy mold will subsequently appear. The problems start in mid October and last thru late March to early April, and by then warmer and drier weather seems to suppress the problem. There seems to be a little uncertainty about the exact nature of the pathogen, some saying its a juvenile or latent form of another fungus, but whatever it is or what form it takes, it is a juggernaut that I need to sally forth and combat. So here is what I've learned over the last 15 years of growing iris in this region.
1) Solarization is not a long term solution -- maybe a season but the fungal spore will reinoculate the iris rhizome over time.
2) A soil mulch in winter to prevent freezing and thawing of the rhizome can help SOME, but that method, suggested by Richard Ernst, now deceased, of Cooleys Iris is very impractical for large to very large plantings like mine.
3) Absolute drainage is essential in the beds as well as exposure of the rhizome to summer heat and sun. We don't get quite as hot as the Southwest or desert regions.
4) Foliage trimming after Halloween to 6" and removal of dead foliage seems very beneficial to allow air circulation into the clump and to reduce foliar hiding places for the fungus
5) Bed rotation seems to keep my clumps from getting attacked as badly, but this lasts only one season.
6) Badly infected clumps ive tossed, bagged and/or incinerated. along with the soil, and replaced it with fresh topsoil in the spot where I removed the clump. This is only a stopgap measure and will last only one season.
7) Susceptibility varies widely from variety to variety with the blues, purples and white varieties being somewhat less affected than the plicatas, luminatas, pinks and browns, and cultivars from warmer regions but color and resistance to botrytis is very weak association, but I thought I'd mention it.
8) All new arrivals are planted in sterilized pots (clean with bleach solution) and planted in a steam sterilized commercial potting mix. They spend the first winter in these pots then are planted in the beds the following spring. This prevents some varieties (especially my 50-60$ ones) from succumbing the first winter. The Aussies and Californians seem to be the most susceptible, but all iris from all hybridizers have been affected at one time or another.
9) As loath as I am to use chemicals, there seems to be no way around it. So here is what im experimenting with --

*** disclaimer -- im not making any recommendations on products here, just experimenting and sharing what ive found out. Your risk is your own if you try the products ive mentioned ***

10) Im using an alternating spraying program beginning in early October every two week using Consan 20 as a spray to wet the lower bases of the fans and rhizomes, followed by Greencure Fungicide -- a potassium bicarbonate based remedy. Alternating applications is essential. This pathogen is notorious for building a resistance rapidly to a single remedy.
11) I take meticulous notes on which varieties are hit hardest and make sure they get treated

The results:
This is the first year I've implemented this program, and ive seen a 20-30% reduction in the incidence of botrytis occurrences. It may not seem like much but I see this system becoming more effective especially on replanted stock with i'll be doing a lot of this upcoming year. Established clumps seemed to be less impacted by the above treatment regimen, but the new plantings fared much better as far as incidences of botrytis infections. That, I consider important. I plan on switching to more powerful remedies such as Strike 50%WP and Clearys 3336 in the future.
I know this is a long fraught post, but if anyone finds my experiences usual, I hope it helps. My research is still ongoing
Last edited by TBMan Mar 18, 2018 9:31 PM Icon for preview
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Mar 18, 2018 9:48 PM CST
Name: Jan Wax
Mendocino County, N. CA (Zone 9a)
I'm a semi-retired studio potter.
Dog Lover Hummingbirder Organic Gardener Daylilies Region: Ukraine Region: California
Irises Dahlias Garden Art Cat Lover Vegetable Grower Birds
That sounds like a scary disease, Tim. Good luck with getting rid of it! Crossing Fingers!
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Mar 18, 2018 10:12 PM CST
Name: Elsa
Las Cruces, New Mexico (Zone 8a)
Dog Lover Irises Region: New Mexico Region: Southwest Gardening Region: United States of America
I am sorry you are having this issue but it is very nice that you share your progress against the fungus with others. Hope you have it eliminated soon (at least in your yard).
I get bored easy and Irises Don’t Bore Me!!!
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Mar 18, 2018 10:27 PM CST
Name: Timothy
eastern oregon (Zone 7b)
Bulbs Region: United States of America Plant and/or Seed Trader Enjoys or suffers hot summers Salvias Region: Pacific Northwest
Peonies Region: Oregon Irises Hybridizer Herbs Dahlias
thanks kindly, my plantings are extensive so im not in any danger of being overrun, but the botrytis issue is annoying enough to warrant a comprehensive approach to the problem. I still have much to sell, and trade with Smiling
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Mar 18, 2018 10:42 PM CST
Name: Evelyn
Sierra foothills, Northern CA (Zone 8a)
Irises Region: Ukraine Garden Procrastinator Bee Lover Butterflies Plant and/or Seed Trader
Region: California Cat Lover Deer Bulbs Foliage Fan Annuals
GreenIris said:I am sorry you are having this issue but it is very nice that you share your progress against the fungus with others. Hope you have it eliminated soon (at least in your fields).


I agree Thank You! Thumbs up Crossing Fingers!
"Luck favors the prepared mind." - Thomas Jefferson
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Mar 19, 2018 12:49 AM CST
Name: Robin
Melbourne, Australia (Zone 10b)
Region: Australia Garden Photography Cat Lover Irises Seed Starter
I have never experienced it, but I love the way you shared so much information to help the rest of us. Thanks Tim Thumbs up
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Mar 19, 2018 3:21 AM CST
Sweden
Forum moderator Garden Photography Irises Bulbs Lilies Bee Lover
Hellebores Deer Celebrating Gardening: 2015 Photo Contest Winner: 2016
Yes, many thanks, Tim. Smiling

I had not previously considered that Botrytis convoluta didn't have any smell, so this was valuable to me. Actually really hard to find good info about many iris diseases.

Mostly soft rot issues here, but I did receive a rhizome last summer, that subsequently showed suspicious symptoms of decay that I disposed of. It had a yeasty or alcohol smell and does not match the symptoms of Botrytis convoluta in other ways either, so I think I can rule that out now.

I bet most large scale iris growers needs to deal with Botrytis convoluta at one time or another, but I don't think all would be so open about it, so thanks again for sharing your experiences.
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Mar 19, 2018 10:09 AM CST
Name: Evelyn
Sierra foothills, Northern CA (Zone 8a)
Irises Region: Ukraine Garden Procrastinator Bee Lover Butterflies Plant and/or Seed Trader
Region: California Cat Lover Deer Bulbs Foliage Fan Annuals
William said:Yes, many thanks, Tim. Smiling

I had not previously considered that Botrytis convoluta didn't have any smell, so this was valuable to me. Actually really hard to find good info about many iris diseases.

I bet most large scale iris growers needs to deal with Botrytis convoluta at one time or another, but I don't think all would be so open about it, so thanks again for sharing your experiences.


I agree and Thank You!
"Luck favors the prepared mind." - Thomas Jefferson
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Mar 19, 2018 1:16 PM CST
(Zone 9b)
Region: California Garden Ideas: Level 1
Timothy, sorry that you (and Brad) have to deal with this.

Would you happen to have any closeup photos of an infected clump, the gray fuzzy mold and a cut open infected rhizome?
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Mar 19, 2018 1:33 PM CST
Name: Timothy
eastern oregon (Zone 7b)
Bulbs Region: United States of America Plant and/or Seed Trader Enjoys or suffers hot summers Salvias Region: Pacific Northwest
Peonies Region: Oregon Irises Hybridizer Herbs Dahlias
UndertheSun said:Timothy, sorry that you (and Brad) have to deal with this.

Would you happen to have any closeup photos of an infected clump, the gray fuzzy mold and a cut open infected rhizome?


I'll take some and post the picts to this thread -- good idea. A visual would help
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Mar 19, 2018 1:35 PM CST
(Zone 9b)
Region: California Garden Ideas: Level 1
Thank you! Thumbs up
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Mar 19, 2018 2:56 PM CST
Name: Evelyn
Sierra foothills, Northern CA (Zone 8a)
Irises Region: Ukraine Garden Procrastinator Bee Lover Butterflies Plant and/or Seed Trader
Region: California Cat Lover Deer Bulbs Foliage Fan Annuals
Thank You! from me too!
"Luck favors the prepared mind." - Thomas Jefferson
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Mar 19, 2018 5:34 PM CST
Northern CA (Zone 9a)
Region: California Cat Lover Dog Lover Irises Enjoys or suffers hot summers
Thank You! from me three.
• “Whoever said, ‘Do something right and you won’t have to do it again’ never weeded a garden.” – Anonymous
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Mar 20, 2018 11:19 PM CST
Name: Brad
iowa (Zone 5a)
I was one of the first 300 contributors to the plant database! Celebrating Gardening: 2015
Tim.. You sound like you have have been battling it too for a while sorry to here that it can be devastating I will get some pictures together over the next couple days so we can compare my plants were hit with a combination of things Rhizoctonia started it I think and what finally did them in was Botrytis going into winter..
I have a diffrent spray that proved effective last year for me will get you the name tomm after 2 years of wipeouts this year only lost a handful to it and most were new plants I bought not my own seedlings so progress..
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Mar 21, 2018 12:43 AM CST
Sweden
Forum moderator Garden Photography Irises Bulbs Lilies Bee Lover
Hellebores Deer Celebrating Gardening: 2015 Photo Contest Winner: 2016
Sad for your losses Sad , Brad, but oh so good that there is a lot less this year. Hurray! Hurray! Hurray!
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Mar 21, 2018 5:44 AM CST
Name: Lilli
Lundby, Denmark, EU
Irises Roses Bulbs Hellebores Foliage Fan Cottage Gardener
Plant Lover: Loves 'em all! Seed Starter Winter Sowing Bee Lover Dog Lover Region: Europe
Progress! Thumbs up
Of course I talk to myself; sometimes I need expert advice!
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Mar 21, 2018 5:56 AM CST
Name: Timothy
eastern oregon (Zone 7b)
Bulbs Region: United States of America Plant and/or Seed Trader Enjoys or suffers hot summers Salvias Region: Pacific Northwest
Peonies Region: Oregon Irises Hybridizer Herbs Dahlias
Will post some Picts later today of affected rhizomes. I may have inadvertently given the impression that im suffering devastating losses, and for that I apologize for any unintended misleading. The vast majority of my stock is healthy, increasing well, and I look forward to s colorful bloom season. The issue has plagued me for years and im challenging myself to get a better handle on the occurrences.
And yeah, Brad - would love to compare notes on your experiences for sure.
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Mar 21, 2018 11:03 AM CST
Name: Evelyn
Sierra foothills, Northern CA (Zone 8a)
Irises Region: Ukraine Garden Procrastinator Bee Lover Butterflies Plant and/or Seed Trader
Region: California Cat Lover Deer Bulbs Foliage Fan Annuals
I treated all of my irises before the storms. It was sunny for the most part of February. I treated them again, before our rain and snow arrived, but it has been raining or snowing ever since. If it stopped snowing, the snow remained on the irises, slowly melting and keeping them wet. I will be surprised when the ground dries out from the last storms if there is no mold.

I am almost afraid to look, but I won't be going out in the rain today, since I can't do anything about until it stops raining.
"Luck favors the prepared mind." - Thomas Jefferson
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Mar 21, 2018 8:29 PM CST
Name: Timothy
eastern oregon (Zone 7b)
Bulbs Region: United States of America Plant and/or Seed Trader Enjoys or suffers hot summers Salvias Region: Pacific Northwest
Peonies Region: Oregon Irises Hybridizer Herbs Dahlias
some botrytis examples -- had to take with my phone camera -- my Nikon Coolpix wasn't functioning properly for some reason --

Thumb of 2018-03-22/TBMan/915e37

and more --


Thumb of 2018-03-22/TBMan/6526e9
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Mar 21, 2018 8:54 PM CST
(Zone 9b)
Region: California Garden Ideas: Level 1
I get some spongy/corky brown rhizomes too. It hits my potted irises really bad in June/July. It starts from the rear and works it's way to the green. I never see any grey mold, so it must be something different. I would love a close up shot of the grey mold if possible.

Thanks for the photos!

I think we need a disease and remedy sticky thread.

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