Managing director of Grove Estate Brian Mullany said he lost about 10 per cent of his vineyard to the hail, with one in five grapes on the west of the property broken or bruised.

Apart from immediate damage, growers are faced with spoilt grapes that could threaten the rest of the crop.

"The actual damage is okay, as long as we don't get the disease damage that could follow," Mr Mullany said. "Hopefully [the damaged fruit] splits and falls off." 

"If we've got berries that don't fall or dry out properly, they become an entry-point for botrytis or grey mould."

Botrytis cinerea, or grey mould, is a fungus that can sap water from grapes, interfere with fermentation or lead to the loss of fruit in large numbers.

"We'll have to monitor them," Mr Mullany said. "It can spread throughout the whole bunch and you can lose your whole crop."

"The weather we've had since the hail has suited us. It's been effective at drying out the hail-damaged grapes."

The hail also dealt blows to the crop's leaves, raising fears some surviving fruit won't reach market.

"That may cause some ripening issues," Mr Mullany said. "If the leaf doesn't work as well, photosynthesis can't take place."

And the hail threatens more than just grapes.

Local agronomist Paul Parker said other crops could be at risk, though their maturity makes serious damage unlikely.

"It can actually knock grain out of their heads," he said. "When the crop's greener, you can get bruising on the stem and even cut the head off."

"Most farmers insure their crops for hail, because this time of year is normal hail time and a harvest has to come in."

Frost also posed problems for local growers, though Mr Mullany says grapes suffered few losses.

"The odd vineyard lost part of their crop," he said. "A couple out in the Kingsvale area may have lost 20 per cent of their crop."

And the price of these crops remains at a long-term low

"The industry has been doing it very tough,” Mr Mullany said. "The price for wine grapes is very low. There still seems to be an oversupply in the market."

Despite difficulties, Mr Mullany maintains an air of optimism.

"The season could be very good," he said. "So long as the weather plays out, it should be a pretty good harvest."