Iris disease, again

[Ewelina Wajgert]

This time, I search the answer, what disease attack my collection of Iris TB. Desease appear on some irises but it attack every day the next iris. I have sprayed the plants with Previcur but I don't know, if it help for this kind of desease. I can buy something else to resuscitate my collection of nearly 400 varietes of irises.

Help me please to identify, what is this.

The 3 photos are made of the same iris - steam and leaf with stains. The steam has much flower buds but they don't flower, because the stem rot at the bottom. Above the steam is healthy. I have cutted out it and third photo show place after cutting.

The fourth photo is from another iris, that has odd stain.

[gote]

Do you know the active substance in previcur??
Göte

[Ewelina Wajgert]

Yes Gote, I have but I don't know, if you understand it. I cann't translate it but we can try

1. propamokarb - complex with HCL, 3-(dimetyloamino)propylokarbaminian of propyl
2. Fosetyl glinowy (aluminium)

Previcur fight with Phytophtora and Pythium.

[gote]

Try to get hold of the substance sold as benlate or Benomyl.
Goggle these names and you might find a source or mail me privately
gote@svanholm.se
Good luck
Göte

[Paul T]

Ewelina,

Do you have Iris Borer in your area?  These are a borer that gets down into the rhizome and the first symptoms you see are the rotting at the base of the leaves and stem.  We thankfully don't have it here in Australia due to our quarantine procedures, but I know iris collectors in the US that have had major problems with it at times.  If it IS that, then you'll have grubs (or evidence of the grubs having been there) in the rhizomes.

[Ewelina Wajgert]

Gote,
I have asked today about benlate or something similar. But this is withdrawn from production.
I have at home still one fungicid, that I try.


Paul,
I had any borer but they were on 1-2 beds in shadow and with more weeds. The another beds were even pure. I have seen its tracks on the irises but they were different. I think this disease is from fungus.

[Paul T]

Ewelina,

I have never experienced it myself, so have no idea of exact symptoms.  I just remember friends talking about the first thing they knew they had Borer was when the fans started to rot from teh base up.  They said there was no visible above ground symptoms that they could see, but the rhizome was severely damaged to the point that they lost complete clumps before they knew they even had a problem.  I hope that yours is a fungal disease that can be salvaged easily enough. 

If they were my irises, whatever the cause I would be lifting the damaged ones and trying to isolate good rhizomes and growing points from them before the whole clump rots from the fungus.  I'd probably cut the leaves off, cut the roots back, and soak them in a fungicide to try to remove any contaminants, then dry them for a few days before planting them somewhere isolated where I could keep track of them.  The most important thing would be to find rhizome that was unaffected by any rotting, so that you knew the fungus or whatever was not inside it.  My concern is that the problem will spread through complete clumps of whatever you have, leaving you with nothing of that variety left to start again with.

[Ewelina Wajgert]

I splashed today all the irises with topsin - fungicid that I hope help to save my collection. I have cut all pralyzed rhizomes.