It looks like fungal leaf spot and is easily controlled with a fungicide. See this from the American Iris Society:
It looks to me that it got sprayed by something.
Looks like fungal leaf spot. You can get a fungicide at a garden center.
Jayme this is from American Iris Society as Douglas mentioned:
Fungal Leaf Spot presents as small circular to oval spots on the leaves, turning yellowish to brown and often developing a distinct red-brown border. The pathogen is Didymellina macrospora. It can affect all bearded irises, Siberians, I. versicolor and the xiphiums, known as Dutch irises. The more rain you have the more prevalent it becomes. It is easy to control with the use of a fungicide and a sticker-spreader in your sprayer. Apply in the fall and early spring before infection. If infected, tip cut the affected leaves and apply again. Maneb have been proven effective. Check with your local authorities as to pesticide and fungicide use.
@Luis what is a sticker-spreader? I have a sprayer, but have never heard of the term.
I know what a Spreder-sticker is: SPREADER-STICKER: a material or combination of materials added to sprays that causes the spray to spread and to stick to the sprayed foliage
I wonder if this is what you are talking about
It could be late frost on it, this is how my yucca leaves look when we have a late frost.
jayme a sticker spreader is also called a surfactant and you can make your own by adding a small amount of ivory dish detergent to you spray mix