As soon as the farmers arrived in The Levee, utes full with produce, they were hit hard by shoppers scrambling to scoop up as much food as they could carry.

When the bread van arrived shoppers had their eyes on one product - flour. It disappeared quickly before they scooped up the bread and pastries.

Ironically the one vegetable that wasn't in demand was the largest of them all, a giant gramma pumpkin, which weighs at least 20 kilograms - clearly too much for shoppers to handle.

Within two hours, virtually everything else in the market had largely been stripped bare.

Vegetable farmer Matthew Dennis was amazed by what he saw, saying the city - and the country - had more than enough fresh food to feed everybody.

"Us farmers can grow enough food to feed 75 million people and I can guarantee we will have more food to bring at the next earth market, and the market after that, and the market after that," he said.

"We've been bringing food to this market since it started in 2016. We're not going anywhere.

"There's no need to panic buy, it's best for everyone to continue to buy their normal amount."

Fellow vegetable farmer Austin Breiner echoed those calls and noted people behaved very differently after World War II when food was not in abundance.

"I remember my parents and others after the war lining up for their rations. They lined up patiently and there was no fighting and no yelling and no jostling," he said.

"They waited for their quarter pound of butter, half loaf of bread and six sausages and went home.

"Now there are fights and everything.

"Where is the character that the people of previous generations showed? They accepted the hard times and got on with it. The behaviour about now, especially fighting over toilet paper, is frightening."

Prime Minister Scott Morrison also expressed his dismay over panic buying this week, saying it was "un-Australian" and 'ridiculous'. He too has urged the country to stop it.

"It is not sensible, it is not helpful and it has been one of the most disappointing things I have seen in Australian behaviour in response to this crisis," Mr Morrison said.

Eleven people have tested positive to coronavirus in the Hunter and are in isolation at home or in hospital. There are now more than 500 confirmed cases across the country.

Extra procedures have been put in place at the market to protect customers, farmers and Slow Food Hunter Valley volunteers.

These include farmers handling the vegetables and designated people handling the money with gloves on.

The market is deemed an essential service and is exempt from government regulations that prevent gatherings of more than 100 people.

Mr Dennis said panic buying now would only hurt farmers in the future.

When shoppers have so much food stored they won't be coming in to buy anything, he said.

"If they don't keep coming like they normally would that will have an impact on all of us, what will we do with the food if they aren't here to buy it?.

"They were wanting everything we had at the market, they were buying eggplant, cherry tomatoes, beans, corn, pumpkins."

Woolworths has extended its restrictions on customers in a bid to stop panic buying.

Woolworths in Pender Place had lists around the store which explained the changes to customers.

There is a 2-pack limit per customer on every product except those that currently have no limits in place, or a limit of 1-pack per customer.

Fresh milk, as of Thursday, is now among the 2-pack limit.

Items like fresh fruit and vegetables, meat (excluding mince), deli products, bakery goods, seafood, canned fish, baby food, yoghurt, wet dog food, wet cat food and Easter confectionery and merchandise currently have no limits in place.

What you need to know about the Coronavirus