Shoppers are being urged to have patience with staff in Woolworths stores on Wednesday as plastic bag bans come into force.

The Queensland government mandated bans don't start until July 1, however, Woolworths has moved to phase out the bags ahead of schedule, with all its supermarkets, BWS, Metro and petrol outlets doing away with single-use plastic bags from June 20.

Research found one-in-five shoppers are opposed to the bag bans, predicting many would be confused by the sudden lack of plastic bags. Credit:Dallas Kilponen

Retail employees union SDA has launched its "Don't Bag Retail Staff" campaign to coincide with the ban.

SDA National Secretary Gerard Dwyer said the ban had been widely publicised and customers needed to bear with staff during the changeover.