BIISC Pampas Grass Eradication: Big Island Now

BIISC Pampas Grass Eradication: Big Island Now

The Big Island Invasive Species Commission (BIISC) is working to eradicate one of Hawaii's most widespread horticultural invaders, and is asking for the public's help in locating any remaining plants. Pampas grass, an aggressive introduction, is a major threat in Hawaii as a wildfire fuel. On Maui, it is widespread, growing in densely vegetated swamps to sparse dry forests, even on the slopes of Haleakala. There are two species of pampas grass in Hawaii, Cortaderia jubata and Cortaderia selloana, and both are targeted on the state's noxious weed list.

Popular in the Victorian era for its showy plumes used in fashion and decoration, this plant was shipped around the world in the late 19th century. In places like New Zealand, California, and Maui, pampas grass has slowly become a problem as it has spread beyond its growing locations. Each clump of pampas grass is capable of producing thousands of lightweight seeds that are carried by the wind, reaching recorded distances of up to 20 miles from the parent plant.

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In 2007, BIISC undertook efforts to remove pampas grass from the Big Island. A comprehensive search over several years revealed pampas grass in more than two dozen sites around the island from Volcano to Kuna. Despite the sharp leaves, pampas grass is still sold worldwide as an attractive planting for homeowners, and many plants are found on private properties, including golf courses. Obtaining permission is always a challenge for any eradication plan, explains Joel Brunger, field operations supervisor at BIISC. “We don't have access to private property to look for or remove a plant, so we have to try to find the property owners, and sometimes they are off-island or out of the country,” he points out. “This process can take from months to years.”

When an invasive plant is found in an area, the BIISC team must conduct a comprehensive survey of the surrounding area to find additional plants, Pronger explained. With the potential to spread seeds up to 20 miles, pampas grass required a significant investment of time. Pronger says most homeowners are cooperative and eager to support the removal of invasive plants from their property. “After removing the adult plants, we have to go back and do regular sweeps looking for new keiki as long as the seeds are viable. For pampas grass, that takes six years, so we can't say the plant has been eliminated until we don't see any new plants in that area for at least six years.

BIISC asks the public to report any pampas grass sightings. The grass grows in large clumps up to 13 feet high, with feathery shafts that range from white to lavender in color. Pampas grass resembles sugarcane, but the leaves are narrower and form a spiral shape, and the shaft is longer and fuller than the cane flowers. Residents are asked to refrain from buying or growing pampas grass, as seeds can be purchased online and have been found twice in stores since eradication efforts began. “It took us a while to get here,” Pronger says. “We would really hate to see all that work undone because of planting one garden.”

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Report sightings to BIISC at (808) 933‐3340 or (email protected). Individuals are encouraged to send photos of suspicious plants via email or Facebook for quick identification.

    (Tags for translation)Big Island Invasive Species Council

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