We recommend looking over the pros and cons of each option in the thorough Univ. of Connecticut publication "Japanese Barberry Control Methods," where they discuss mechanical versus chemical options. In short, a two-step approach is likely the most effective, even if slightly more labor-intensive than just using herbicide alone. We do not have information about which process would be the least expensive. Ohio State Extension also has good information in a fact sheet about telling the difference between Japanese (the species predominant in MD) and European Barberry, plus options for removal: "Invasive Species Management: Common and Japanese Barberry." Additional control tips for comparison include Penn State Extension that has a chart timeline for each control method, and the Michigan Dept. of Natural Resources' publication which notes that spring application of a systemic herbicide probably won't work well since the main sap flow is going to the wrong way to bring absorbed chemical effectively down into the roots.

Miri