The enemy: noxious weeds.

Six ACT Parks and Conservation staff have joined forces with the NSW National Parks and Wildlife Service this week on the main ranges of Kosciusko National Park to defend the landscape against a horror weed that can decimate biodiversity.

ACT Weed officer Steve Taylor said the battle against mouse-ear hawkweed had been long and government's were pulling out all stops because the European plant changed the soil chemistry where it grew rendering it inhospitable to other plant life.

"It is a very high-risk weed and can be devastating," Mr Taylor said. "Entire hillsides in New Zealand have had all the native plants destroyed and the only thing growing there now is mouse-ear hawkweed."

The utmost rigour was used to scour sites in need of protection such as nature reserves, national parks and farmland.

"Its a huge operation going on on the main range in Kosciuszko," Mr Taylor said.

"They do line searches like police, if no plants are detected they send a drone through for imaging and then the dogs to guarantee the search area is clear."

Mr Taylor said the encroachment of such species meant areas lost native plant life, which reduced habitat for insects, then wildlife and so on.

Similar efforts have been made to rid Namadgi National Park and Tidbinbilla Nature Reserve of the invasive weed including the ACT government loaning a NSW hawkweed sniffer dog named Sally to double check the sites.

ACT authorities are keeping a close eye on the dodder weed, after an exotic form of the parasitic plant called the small-seeded alfalfa dodder, was found for the first time in the ACT last week suffocating a pot plant in a commercial nursery.