Kingsmill Wines Ltd owners Phillip Horn and Donna Abrams have this week been assessing damage to their Hall Rd vineyard, thought to have been caused by wind gusts on Friday.
Mr Horn said a neighbour alerted them to damage, which they had been unaware of, on Monday morning.
"Our neighbour looks down on our vineyard and noticed the nets on about one or two acres [0.4ha-0.8ha] of vines were missing.
We couldn't see the damage from ground level as it was surrounded by other vines, but when we inspected it we were amazed," he said.
A net from the vineyard had been blown on to the top of a hill about 500m away, although there was no sign of others probably "ripped to shreds", he said.
The result was a large area of vines without nets, completely surrounded by netted vines, resembling a hole in the vineyard.
"It must have been a tornado or twister because the nets were sucked right up into the air. We didn't see it happen but Donna was inside on Friday when she heard a `whoosh whoosh' sound.
"She assumed it was gusts of wind but didn't think much of it," Mr Horn said.
He and Ms Abrams bought the property in 2000 when they established the vineyard.
Neither had seen anything like a tornado in Bannockburn, although Mr Horn recalled an incident in January when wind ripped off part of the Bannockburn Hotel's roof.
"It's quite something - a bit of excitement in our lives," he said.
An insurance assessor had been notified and vineyard staff were compiling reports of damage and its estimated cost.
"The cost of repairs, replacing nets, and labour will probably be at least $10,000 so we hope insurance covers it," Mr Horn said.
Grapes had been picked and damage to vines was not considered major, he said.
Mr Horn said there was no other sign of recent wind damage around Bannockburn.
