A TASTY treat is wreaking havoc across Warwick.

Blackberry vines are the region's worst weeds.

Joining the hit-list are sisal hemp, tree pear, african love grass and parthenium.

Queensland Parks and Wildlife Service south-west region principal ranger James Haig said the pests were invading native habitats and grazing land.

He said the community needed to take control to thwart the spread of the pests.

"The best thing you can do with weeds is always to prevent them getting spread in the first place," he said.

"It's much easier to control the infestation when it's either very new or prevent it happening in the first place.

"As visitors to parks in particular, one of the things they can do is drive on the formed roads that tends to reduce the likelihood of any seed that might be on your vehicle getting into a bit of disturbed earth where it can get started. That's a pretty important thing to do."

Mr Haig said gardeners were also adding to the region's weed problems by planting pests like mother of millions.

"Weeds don't have recognition of a line on a map - they just spread down suitable habitats so working together is the most effective way of doing it and that seems to be where we get the best results when we're working with neighbours to try and control things," he said.

TOP THREATS

•  Blackberry vines: Major threat, particularly prevalent in the Southern Downs Regional Council area.
•  Sisal hemp: Threat to native plants in the Sundown National Park.
•  Tree pear: Cactus related to the prickly pear. Found everywhere.
•  Africa love grass: Common along roads and a major pasture threat.
•  Parthenium: A major pasture threat.

Source: Queensland Parks and Wildlife Service