Commenting on a Massey University study, Mr Young, of Dunedin, said creditors should start asking why the business was using its credit card instead of an overdraft.
"It may well be the most efficient method and, if it is, that's great. But maybe it is because the bank has said no more overdraft. It won't be long before there will also be no more credit card," he said.
The Massy University centre for small and medium enterprise research surveyed 1808 small and medium-sized firms as part of a study to find out how they were coping with the recession.
More than three-quarters of the respondents said they were now using credit cards - an increase from 67% in the previous corresponding period.
Centre director Prof David Deakins said that now made personal credit cards the most widely used form of business finance alongside trade credits.
"These findings reflect the fragile nature of the recovery as the recession continues with businesses not wanting or not able to access a bank loan."
For a business owner, that was a relatively flexible way to finance cash flow and meet working requirements, he said.
There was a risk they might get bad debt - particularly in times of recession - but if it helped cash flow over a temporary period it could be a good solution.
Mr Young said larger business, and some local authorities, issued staff with credit cards because of the efficiency of keeping track of expenses.
"But for a small business, that is a neon sign pointing to potential pressure points for cash flow. You have to monitor those companies closely."
One of the problems facing companies in the South was when to start collecting debt following a natural disaster, like the February 22 earthquake, he said.
After the earthquake, businesses stopped sending invoices and statements as they awaited news from Christchurch.
Mr Young suspected that some of the businesses funding their businesses through personal credit cards were either Canterbury businesses or businesses who usually sold into Canterbury and who were yet to be paid.
"The technical answer to the question is that businesses should mirror public opinion. It is not how the debtor sees you but how your good customers see you."
Businesses should be monitoring what Christchurch Mayor Bob Parker was saying about the conditions in Christchurch, but Mr Young believed it was the time to start sending invoices and statements to Christchurch.
New Zealand Post was able to deliver 95% of mail. Immediately after the earthquake, no mail was delivered for more than a week and cheques were left sitting in mailrooms.
Many businesses had bought a "disaster pack" but no-one had given thought to how to manage credit control in the wake of a disaster, he said.
Before speaking to Christchurch debtors, suppliers should understand what was available for business owners in the region. When talking to them, a supplier could then go through the options available to them, Mr Young said.
The annual Massey survey was a yearly longitudinal study of small and medium-sized firms in New Zealand.
It also found that a quarter of businesses surveyed had invested personal savings into their companies last year. That remained "fairly stable" with 27% in 2009 compared with 25% in 2010.
Prof Deakins said firms that were not growing had stopped investing personal savings into their business, indicating that some had exhausted that option of finance.
The study also found that companies were still feeling the effects of the recession, with only 14% reporting they had not yet been affected, compared with 27% in the previous year.
"This clearly indicates the depth of the recession and the prolonged effect it has had on businesses," he said.
