Winegrowers say their industry is fragile and under siege.

The comments come in the latest wine industry business confidence survey conducted by business advisors Markhams.

It says bad weather, bulk wine sales, volatile exchange rates, fluctuating supply and demand for grapes, and a lack of confidence in government policy are all dealing heavy blows.

More than half of winegrowers surveyed reported they weren't trading profitably, though 26 per cent of those say it is because they are in the early stages of development.