Germany’s Verdi union has called on Lufthansa ground staff to walk off the job and strike on Wednesday, to increase leverage in salary negotiations with Germany’s flagship carrier. The strike is scheduled to start at 3:45 am (0145 GMT) on Wednesday and last until 6 am on Thursday. Verdi is negotiating on behalf of about 20,000 ground staff crew members, including technicians and logistics workers, without whose services the planes cannot take off. Verdi had rejected an initial wage offer from Lufthansa, but agreed to continue negotiations on August 3-4. The union is demanding 9.5% pay increase…