string path = "D:";
string wbadminPath = Environment.SystemDirectory + @"\wbadmin";
string wbadminEvent = "start systemstatebackup -backupTarget:" + path + " -quiet";

        try
        {
            int exitCode = 0;
            ProcessStartInfo start = new ProcessStartInfo(wbadminPath, wbadminEvent);
            using (Process proc = Process.Start(start))
            {
                proc.WaitForExit();
                exitCode = proc.ExitCode;                    
            }
        }