Brown leaves on irises
Brown leaves on irises in early summer. What's causing it and how do I fix it?
Certified GKH Gardening Expert
This could be happening either because of root borer or Iris Leaf Spot or underwatering.
Make sure the plants area getting enough water and check the roots for borer activity (it will literally look like something bored into the tubers). This article has more information on leaf spot: