Thank you for the question.  It looks like a caterpillar has chewed the edges of the leaves.  You can't treat the problem unless you know what it is so I suggest you scout your shrubs very carefully.  Look under the leaves and on the stems, including the base of the plant.  It might be helpful to scrape away some of the rock to look for pests. 

Barberry looper is a colorful caterpillar that is know to feed on the shrub all summer.  Read more here:  http://msue.anr.msu.edu/news/nursery_insect_update

Thank you for contacting Extension.

It's possible that your shrubs are being attacked by both insect and disease but the leaves with the clearly eaten margins are being eaten by an insect, probably a caterpillar.  The photo of the plant with no leaves show leaves eaten down to the base.  Barberry prefer partial sun so if they are in full sun, it's possible there is some leave scorch.  Typically barberry are quite resistant to disease and insect pests.  Please review our publication on possible problems with barberry to see if you can identify any other issues:  http://www.extension.umn.edu/garden/diagnose/plant/deciduous/barberry/

Another option is to send a sample to the University of Minnesota Plant Disease Clinic:  https://pdc.umn.edu/