You will probably have noticed that the creamy white or violet flowerheads of pampas grass are currently just starting to emerge from amongst the leafy clumps. There are two species of pampas, Cortaderia selloana and C. jubata, the former being the most common. Both species originate from South America and were introduced as a shelter plant and as a source of fodder for stock.
Unfortunately pampas has found New Zealand conditions much to its liking and has since spread into river beds, pine forests and marginal land over much of the North Island. Each flowerhead may contain 100 000 seeds which can be blown long distances. It competes vigorously with native vegetation, often displacing it completely.
In the Opotiki area, pampas can be seen at its worst in and around the Motu River mouth; sadly this particular display is not, as is commonly thought, our native toetoe which belong to the same genus and is easily mistaken for pampas. Toetoe flowers in the spring with light, golden yellow flowers, has white, waxy leaf bases and its leaves donít curl into spirals as they die. Two species of toetoe are found in the Opotiki district and both are now displaying their pale, dried, spent seed heads.
Small clumps of pampas are easily dealt with by digging out or by spraying with glyphosate. Larger plants are a bit more of a challenge but will succumb to a thorough covering with glyphosate or Gallant herbicide (the latter needs the addition of a wetting agent).
For more information, or if you need to check whether you are about to kill a pampas or a toetoe, contact your local regional council pest plant officer.