Yuck! Iris rust! What to do?

20 years ago

I just figured out why the insecticidal soap that I slapped on my iris leaves last week didn't do any good: I've got rust, not bugs. The site where I identified it says I should remove affected parts and treat with fungicide.

(1) What is the least poisonous fungicide I can use? I've never used anything stronger that insecticidal soap in the garden and I'm not happy about having to buy and use it.

(2) I'm not all that happy about cutting leaves off either. Do I really have to do that if I use fungicide? That will certainly slow increase-- if not kill the rhizome all together.

(3) It only affects a small part of my garden, but it has clearly spread since I first noticed it. I was planning to divide a couple of these and bring them to the local iris sale in July. If I dip them in a bleach solution (or fungicide), are they OK to share?

I thought I had really good garden hygiene, cleaning up dead leaves and debris religiously. I wish I had taken the time earlier to look more closely. I saw it but thought it was aphid damage!

Here's a picture of RUST. It is described as looking like little blisters full of (you guessed it) rust.

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Comments (7)

jain
20 years ago
its nothing to worry about, since its been so cool it will grow out when summer comes, unless you live in the fog belt... i never treat and it always disappears. we have been so cool this last week i can't believe where i live anymore... pulling leaves is the easiest now since its clean up time.
iris_gal
20 years ago
I don't know if fungicides are rated. I have heard people recommending Daconil (sp?), but as Jain says the new leaves will emmerge clean & free of it. About 7 years ago there must have been the perfect weather conditions. Every iris within a 20 mile radius had it. Following year hardly any.

I think would be a case of locking the barn door after the horse has fled to spray now. When you see it beginning in the spring, spraying will innoculate the uninfected leaf portions. Luckily this fungus is peculiar only to iris family members.
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jayteadesigns
20 years ago
I (have) had the same problem with my irises and I use 'Garden Fungicide' that is made by 'Safer' and it works quite well. (The active ingredient is sulphur).
I would say not to buy the ready to go spray bottle of it. It is so much cheaper to buy the concentrate and make it up by the gallon and put it in a spray bottle that you already have.
Hope this helps,
jt
terry94705
Original Author
20 years ago
Just to follow up... Jain was right. I cut off the worst leaves and the new leaves grew out without rust. It looks fine now.

I also got a soaker hose. No more overhead watering. I think overhead watering made it worse.

Terry
rootedinreadyville
20 years ago
Everyone seemed to have leaf spot (rust) on their irises in my area accept for my favorite commercial grower. I begged him for his secret, and he told me he uses Hi-Yield Consan 20. I ordered it over the internet and it works better than anything else I've ever tried.

Here is a link that might be useful: Hi-Yield Consan 20
Sparaxis
20 years ago
Why use a toxic chemical, with very little available information on carcinogenic properties, to fight something that really doesn't need fighting?

Here is a link that might be useful: consan triple action 20
rootedinreadyville
20 years ago
I've only used it the one time. The commercial grower who told me about it said he used it once last year and didn't need to use it this year since his irises didn't have leaf spots. I'm keeping my fingers crossed - maybe one treatment will be enough in my case too.