It could be both., but the borers aren't going to be very big this time of year yet.
Spring was wet, wet, wet. We broke all records on rainfall since 1871. I lost a lot of iris this year. Even in beds that are slightly raised and some that had drainage trenches dug around them. I also had a thick, suffocating layer of ice all winter rather than snow.

The iris problems won't bother the daylilies. The daylilies seem to be able to take a bit more moisture. Mine got off to a very slow start but are catching up now.

Hasn't been very good iris weather in the northeast. You can drink the air right now.

I haven't had much luck controling borers organically. I'm afraid I have to breakdown and use a systemic insectide every couple of years. The cleanup and hand squishing worked when I only had a few iris. Now it's too much.

If your iris aren't raised a bit I'd raise them after bloom. Apply a fungicide of some sort. Garden sulfur works fine if you follow it with lime about 2 weeks after. The sulfur is acid and the beardeds prefer it a bit alkaline. If they are beardless don't use lime. Sets them back bad and sometimes kills them.

Borers cause rot, so you really can't tell unless you examine more closely for the grubs.Look for chew marks and/or weepy marks on foliage. I agree that at this time of year, the borers are still small and have not eaten their way down to the rhizome yet, so rot from borer is not likely. You probably need better drainage.
Laetitia

Thanks so much for your information and advice. My bearded irises are in raised beds on top of our septic leach field, since the iris roots are shallow, they stay right in the 6 + inch raised bed. The Siberians and Japanese iris are in another moist location. With all the moisture this year, my roses already have black spot, I have 223 roses of all types. More rain this weekend, just what we DO NOT need.
Thanks again,
Joan