Five barberry against a brown brick building. They get full morning and early afternoon sun-complete shade after that. They appear to be burning but I'm not sure. What can I do to determine if they are burning or if something else is happening?
The first thing is to consider how long the plants have had this problem. If they'v been in for several years, and the burn appearance has always been there, that's a good vote for burn. If the problem just started, it's more likely to be a disease. You can take some leaf samples to an Extension Service for analysis. This article will tell you more: https://www.gardeningknowhow.com/garden-how-to/info/what-is-extension-service.htm