Brown on iris leaves can be any of several things. That browning at the tips is normal - it just happens as the season progresses. Additionally, the outside leaves on a fan turn brown and die over time. All normal. However, if the leaves in the center of the fan are turning brown while the outside leaves are not, that's a sign of trouble. Could be borers, could be rot, could be both. You will not necessarily see an entrance hole from borers if you don't dig the irises. Chewed foliage doesn't happen on all fans, only on the fans the eggs were laid on as they work their way in, and then the borers move through the clump underground.

This late in the year, there's an easy test for borers. Poke the rhizomes. With your finger or whatever, and if there are borers in your clump, you'll have rhizomes that just cave in when you touch them - hollow. Usually the bigger rhizomes. This isn't really a reliable method until mid-late summer, though, because this is when the borers are big and fat from having eaten a lot, leaving you with hollow rhizomes. Earlier on, when they're smaller, they can munch away on a single rhizome for quite a while before they hollow it out.

If you do find borers, kill any that you find, and then depending on your ambition level, you can:
1. Dig them, clean them up, soak them in a 10% bleach solution and replant (preferably in fresh soil).
2. Do nothing. It is late in the year, and the damage is mostly done. If they didn't eat all of the increases, the irises can recover. (However, if there is a lot of rot present in any clumps, you will want to address that.) Burn the debris or put it in the garbage. (do NOT compost it!)

In either case, do a good clean up of the clumps either this fall after frost hits or next spring (I do both). Next spring, before temps get to 70 degrees but after the irises have started actively growing, treat them with a grub control product containing imidacloprid. Bayer makes a product called Merit Lawn & Grub Control. It works. I don't like using chemicals, but I had borers get into my beds in Ohio, and I had to stop them so I didn't bring them with me to IL, and it did the trick. I dug every one of my irises this summer to move them here, and not a single borer. Evidence of them, yes! There would be chewed spots and then it just stopped. Presumably, because they died. *Evil laugh* Unfortunately, however, I found that several large clumps of iris at the new place were infested with borers, so I am not starting fresh at the new place as I had hoped. Argh. The application rate of the Merit was a teaspoon per clump, (per Laurie's recommendation - thanks, Laurie!) applied directly on the clump, so it would soak in right around the roots for the plant to absorb. A little more for large clumps, a little less for single rhizomes. Apply before a rain or water it in, and keep critters out of the bed until it has soaked in well.

As for those violets, if they're not causing problems with air flow around your irises, thus encouraging leaf spot, rot, etc., and they make you happy, leave 'em. I'd just keep them thinned out so they don't get too thick and pull them out right around the irises maybe to give the irises a little elbow room.

I hope this helps you get some sleep tonight!
Diana

Oh happy day! The rhizomes are rock hard and the brown streaks are in the outer leaves, not the inner ones. Thank you so much for sharing your expertise and putting my mind at rest!
Ginny