A third of Australian wineries could go to the wall in the aftermath of the coronavirus crisis, according to the industry's peak national body.

"We've got 2,600 wineries at the moment and 30 per cent of that we could lose," said Tony Battaglene, chief executive of Australian Grape and Wine.

On March 30, following an outbreak of coronavirus among international tourists visiting the Barossa Valley, the South Australian government ordered the closure of all winery cellar doors that supply direct to the public.

Those state-based restrictions were relaxed this week to allow takeaway sales of alcohol and food.

While there weren't the same orders in all other states, the lack of tourism due to travel restrictions and the inability to serve sit-down customers has meant cellar doors everywhere have closed.

In South Australia's McLaren Vale, Hugh Hamilton Wines was closed over Easter, traditionally a very busy time which financially sets up businesses for the winter.

"We are very much a wine business that focuses on selling wine directly to our customers and the cellar door is our lifeblood — that is where they first meet us," said CEO Mary Hamilton.

Ms Hamilton said her business sells wine through the large wine retailers but also directly markets to customers via an online store and wine clubs.