NEW YORK: Katy Perry says she’s pushing back the start of her new tour because of “unavoidable production delays.” The pop star’s “Witness: The Tour” will now begin September 19 in Montreal. Perry said in a statement Thursday that “major elements of my tour stage design could not be available for me to rehearse on until this week.” The tour was originally planned to kick off September 7 in Columbus, Ohio. Tickets purchased for the original concert dates will be honored at its new date. Refunds are also available at point of purchase. Perry said that she’s “sorry for any inconvenience this causes.” The singer also announced that Carly Rae Jepsen, Noah Cyrus and Purity Ring will open for her on the road.