If you find out what it is, let us know. Some of my iris have something and at first I thought it might be the borer, but because my daylilies also have something similar I would assume the 2 are related.

Kevin

there is an iris forum.. with many real pro's on the subject.. otherwise.. stay here ...

i THOUGHT.. you were supposed to simply fan out.. cut off ALL THE GREENERY.. to about 6 inches.. and just throw that stuff all away.. at this time of year ...

thereby basically.. throwing away all what you are concerned about ... except for spraying.. in early spring.. for borer .. i am not sure there are many things that an iris require.. spray wise ... i consider them one of the bulletproof plants .. that i totally ignore.. but for cutting off the old leaves ... when and if i get around to it ...

i didnt check your link.. but you seem excited about it.. but i question how good it all is.. if it made you dig up a plant.. for no real reason ...

ask the iris peeps... see what they say .. and link us over there.. please ...

ken

When I grew a lot of iris, I was told to cut off the foliage in fall and toss it 'cause that's where next years eggs are at. In spring, one was suppose to spray with Cygon to kill the hatching larva. I believe Cygon is in the process of being banned or maybe it already has been.

I probably did that regiment a few times and realized it wasn't worth the effort to me. Hence not that many iris anymore. If you do find an iris with borer and dig it up, the whole thing is really gross. They look like really big fat maggots.

Kevin

Iris rhizomes should not be buried. If they are exposed, they should have no borers or fungus. No spraying or leaf trimming required.

mine are properly on the surface.. and every few years.. i get borers ... proper planting depth is imperative.. but not borer related .. as far as i know ... could be wrong ...

cygon is off the market ... like ALL the good stuff.. lol ...

ken

Ken, Hmm... interesting, I don't know. I thought that was the reason for putting them on the surface - to create a less desirable environment for borers and fungus. Not to be argumentative, but genuinely asking, since you see borers "every few years" does that coincide with the Irises having been buried a little too much by leaf litter/stray mulch/just having dug themselves in/time to pull and divide? I honestly never paid any attention to Irises (as a newbie I decided they don't grow well that way, kind of shy - don't look at me when I'm not blooming and don't water me!) except to notice "every few years" I couldn't see the rhizomes anymore and would then pull them up, separate, replant. Since there were always so many more than the last time, I never considered the few "icky" ones much of a problem. Hope I'm explaining that well... ?

Thank you all, I normally don't do anything to my irises. I dead head IF I have time, dig and replant every so often, and weed them. They are properly planted so the rhizome gets kissed by they sun, (as my MIL taught me 30 years ago) and I never cut the leaves, in fact I leave them until spring clean, as they help catch the snow for a nice blanket in the winter.

This patch is planted in full sun, a newest planting with plenty of space, and not crowded at all. If you look at that link I sent, this patch looked just like that but 10x's worse. This is why I suspected something was going on.

I can't find any information on what to use for this, and I did post on the Iris forum, but have not had and answer yet.

I am thinking its just because of our damp weather, and an anomoly for this year. I am not going to worry or stress over it.

Jenny P

There is a relationship between planting depth and rot.
There is a relationship between rot and borers.
There is no relationship between planting depth and borers.

There are various bacterial leaf spots that affect irises. Looking at that picture, that's what is going on.

Aha, thanks for the specification, mad_g. The rot "invites" the borers. A missing step in the process, but does not change the advice. I didn't look at the picture as I don't visit blogs in regard to forum questions such as these, nothing personal in regard to the OP. Looking at it now would be pointless on my part since I know nothing about bacterial spots and could not confirm nor deny the theory.

In the UK, this is exactly the right time to dig up, split and replant, cutting off all the old foliage so I would say go ahead and cut the itis back hard. At this time, iris leaves tend to look pretty sordid anyway, so they are cut back whether they are divided or not. It also ensure the rhizomes get a really good baking in sun.

This iris thing just kills me. There is a guy down the street from me who has his irises planted SO DEEP that I go nuts every time I walk by. But GUESS WHAT...... he has the biggest, most beautiful iris blooms I have ever seen every single year. And mine are planted properly on top of the soil (practically speaking) and I get nothing. He even adds compost to those irises every frigging spring. I can't stand it.

Some areas have borers, some don't. If you're lucky enough to live in an area without iris borers, your iris won't get borers regardless of when you trim the foliage or how deeply you plant the rhizomes. My soil is heavy clay. If I buried iris rhizomes, they would absolutely rot in winter. Since our winters are wet, I remove the foliage in autumn along with any fallen leaves that have blown into the beds. Still, I get a couple of borers each year.

Patann, I wonder if you have sandy soil. In sandy soil, fertilizing iris with compost or another organic once a year would be a good idea.