Threats posed by invasive introduced weeds are not as well known in New Zealand as those posed by introduced animals. There are almost 25,000 known introduced plant species, of which almost 250 are recognised as serious conservation weeds.

These weeds range from climbing vines and creeping ground covers to grasses and seaweed. They can be found in just about every habitat in New Zealand. Some of the best known include wild ginger, tradascantia, old mans beard, pampas grass and contorta pine.

Without control they threaten to displace native plant species, reduce the diversity of our natural ecosystems, transform the landscape and reduce the availability of food for birds, invertebrates and lizards.

Weed control programmes funded by the NZBS and carried out by the Department of Conservation focus on areas of highest biodiversity value on public conservation land.

In the first two years 111 new weed control programmes have been carried out. Weed surveillance plans for each conservancy in New Zealand were completed – marking a change from reacting to well established weed problems to actively searching for new weed invasions while they are still manageable.

A new standard operating procedure gives staff procedures and funding to actively search for weeds that are new to New Zealand or to a particular region. If found early, there is a good chance the weeds can be totally eradicated or contained.

Inventory and threat assessment work has been carried out for 38 important conservation sites. A significant step forward was the completion of a national weeds database containing 60,000 entries about weed identification, location and control methods. This database is now available to regional councils who can access it over the Internet.

Over 70 per cent of invasive weeds present in New Zealand were originally garden plants. The public therefore have an important role to play in containing weed spread by making themselves aware of problem weeds and dealing with them carefully.

People continue to spread these weeds by growing them in their gardens, dumping rubbish from gardens or fish tanks, or accidentally spreading seeds and plant fragments. The Department of Conservation website has links and further information about weeds and control programmes. Your local or regional council, responsible for weed control programmes in their areas, can also provide information about what is going on near you.