Finding this in my iris . . .

What is it and how do I treat it?

Thank You

Appears to be a common fungal leaf spot. I believe you must treat the iris early
in the spring with repeated applications of a fungicide. Once the spots begin to
spread down the leaf it is too late. Best treatment now is to cut the leaves off
low to the rhizome or, as I prefer to do, give them a twisting tug if they are brown
or otherwise discolored at the base. Burn them or put them in your yard waste
bag if you have a city trash pickup. Our garbage pickup prohibits yard waste in
the garbage. I do not think you are supposed to compost them but I defer to
the experts.

At this time of the year, I pull off all the leaves which are spotted and turning
brown. You will know if they are ready or not. Do not pull in such a way you
move the rhizome. I see a lot of new babies trying to break out from behind
old leaves so it does some good and also cleans out the bed and allows more
air and sunlight in.

I believe that is Iris Leaf Spot, a fungal disease:

http://www.tulsamastergardeners.org/plant_pathology/webs/leafspot.html

It was a real pain for me when I lived in a wooded area. Now I'm in an open sunny area, and still see a bit from time to time.

burn - do not compost. you were right, Oldgardenrose. I don't even put them in the yard waste, as our yard waste it composted and sold by the city.

Oh, thank you so much; I will take care of it! So it is not iris borer?

Nope, that's an altogether different monster, LOL.

I'd never seen it other years but this year has been cooler and more moisture. You guys are just great to help out when I'm sitting here in the middle of no where wondering what to do. Puts my mind at ease. Thank you again.

TwinLakesChef, you just described perfect fungus weather, and that's what this is!

Well, my daylilies are affected too. Once the cleanup is done, I'll spray Daconil and again in the spring; my beds look so bad.