Mayor Annette Main said the district council economic unit was creating more retail opportunities while the council was looking at ways to use empty shops to revitalise the city centre.
"We may not be seeing as many retailers in the central business district as we have done traditionally, but it doesn't mean our local economy is in decline," Ms Main said.
The council had been working with local companies to review supply chains and identify sany suppliers from outside Wanganui to see if they could work with established operations here.
Other target sectors and companies had been identified and business cases were being developed to pitch to them. "Other town centres around the world which have lost retail space because of changes to the industry have developed hubs in the centre of town to revitalise the area with great success," Ms Main said.
"We are aware of changes to traditional retail and are already making moves to create the kind of buzzing, community hub we want to see in future.
"The changing face of retail internationally is causing empty shops, but this isn't unique to our district."
Councillor Ray Stevens reacted more stridently and suggested that council could retaliate.
"The programme is called the Westpac Grassroots Road Trip - this is the same bank which trumpets the fact that it's 'the bank that's helping NZ businesses grow'," Mr Stevens said.
"If that's Westpac's way of helping grassroots New Zealand, then I'm going to suggest that our council stops using Westpac and takes its business elsewhere.
"The programme may not have talked about Wanganui being a zombie town but this was just another way of someone putting the boot into us."
Councillor Helen Craig spoke on the radio show and said the council was working proactively to sort the situation.
Mrs Craig said the growth of empty shops was not unique to Wanganui and was happening everywhere as "big box" stores moved out of central business areas to sites that provided more space, especially for parking.
Other Wanganui people were quick to respond to Garner's comments, too. Mel Evans said she had lived in Wanganui most of her life and it was not dying.
"In fact, I have seen this city progress so much in the last few years - some shops have had huge upgrades, some have moved into new buildings, leaving spaces for new ones," she said. "The amount of shops does not make a city great, it's the people."
Courteney Nixon suggested if Garner lived and work here he would realise there was nothing wrong with the city.
"You come here and judge by what is around you, but don't realise this town is people's lives - families have grown here, bonds have been created.
"I think you see it as an easy target, but if you're not from here then your comments are invalid," she said.
Michael Lockwood said empty shops were more about the impact large retail outlets had on smaller, traditional stores.