Hawaii has renewed efforts to revamp the official list of harmful weeds in the islands for the first time in 30 years as foreign flora threaten local crops, habitats and ecosystems.

The state’s noxious weed list includes 79 species, which means the agriculture department may target them for eradication and restrict the plants and seeds from being imported and sold.

But it hasn’t been updated since 1992, and local environmentalists are pushing to add several plant species, including Barbados gooseberry, rubber vine, a second species of pampas grass, cape ivy and more.

The problem has grown as plants from elsewhere are often used for weddings and other ornamental purposes and are more easily obtainable and commercially sold online, says Christy Martin, program director for the Coordinating Group on Alien Pest Species.

“Sometimes the laws and rules don’t match what the need is, that’s really the heart of it,” Martin said.

The Maui Invasive Species Committee continues to grapple with eradicating pampas grass.
Environmentalists are taking matters into their own hands by eradicating potential noxious weeds like a second species of pampas grass. Courtesy: Maui Invasive Species Committee

There was an effort to update the list in 2020, but financial restrictions imposed by the coronavirus pandemic dampened that effort.

Helmuth Rogg, administrator of the Department of Agriculture’s Plant Industry Division since last September, said he plans to pick up the pace early next year and may come up with a draft of a new list by the summer.

But he said the process of finalizing the new list may take up to two years since it will include changing the Hawaii Administrative Rules in order to update the noxious weed list, including figuring out which plants pose a threat to the state’s environment and agriculture.

The process also will involve a study of potential noxious weed species, public comments, assessments from advisory committees, legal advice and final approval from the Board of Agriculture.

“Reviewing the list of noxious weed species will be the challenge,” Rogg said.

Barbados gooseberry is one species of plant that environmentalists want on the noxious weed list.
Barbados gooseberry is one species of plant that environmentalists want on the noxious weed list. Courtesy: Hawaii Invasive Species Council

Environmentalists in county-level invasive species committees – comprised of voluntary partnerships of state government, private and nonprofit organizations and community members – have taken matters into their own hands.

Martin said the invasive species committees are responsible for identifying which plant will be harmfully invasive and will go after it without having the “noxious weed list to back them up.” The committees rely on homeowners to voluntarily remove the plants but find it harder to persuade people to do so when the plant isn’t on the official list.

“The department created the rules and list, but it doesn’t fit what the public needs right now. The invasive species committees are going after the plants that are more invasive but can’t wait to go on the list because it takes too long,” she said.

‘It Only Takes One Seed’

Pampas grass, which is native to South America and popular for its golden, feathery plumes that often adorn weddings, homes and landscapes, is an example. The large clumps of lush, grass-like foliage can produce up to 30 plumes, each containing thousands of seeds carried by the wind.

And it’s high on the target list of local environmentalists.

While one species – Cortaderia jubata – is on the state’s noxious weed list, the other – Cortaderia selloana – is not. Although both species are listed on the state Department of Land and Natural Resources’ invasive species list, it’s only an advisory list. The DOA’s noxious weed list allows eradication and control efforts to rid the state of harmful plants.

There’s also a federal noxious weed list, but that only regulates plants from other countries. The state regulates domestic imports.

“The federal government can remove a federal noxious weed growing in Hawaii, but it is really hard to get a Hawaii weed listed on the federal because those are primarily weeds of major U.S. crops and national forests,” Martin said.

Pampas grass is known for its fluffy plumes, beautifying much of social media, weddings and homes.
Pampas grass is known for its fluffy plumes, beautifying social media, weddings and homes. Courtesy: Maui Invasive Species Committee

Pampas grass, which also comes in pink and purple shades, has been in Hawaii since the 1920s, but the much taller Cortaderia jubata species only began arriving in 1991. It was put on the banned list the next year because it spreads faster according to Mike Ade, plant coordinator for the Maui Invasive Species Committee.

However, he noted that both species of pampas grass produce seeds and spread quickly so it’s important to have both on the list to prevent the plant’s spread. Clumps can grow up to 12 feet tall and expand about eight feet in diameter.

“It only takes one seed,” Ade said.

Not only does pampas grass affect native plants, it poses a fire risk because of its dry foliage. Its razor-sharp leaves also make it difficult to remove.

Local efforts against it have had mixed results, with the Big Island announcing in 2020 that it had eradicated pampas grass.

Oahu is close to doing so, with only three sites remaining, including the Makaiwa, Kaloi and Keehi watersheds, according to Erin Bishop, an outreach coordinator for the Oahu Invasive Species Committee.

On Maui, pampas grass has populated marshes, forests and the slopes of Haleakala. And it continues to spread.

“Here on Maui, we have a lot of open space and pristine environments that it can colonize easily,” said Serena Fukushima, outreach coordinator with the Maui Invasive Species Committee.

According to Ade, trade winds can carry the seeds up to 20 miles. He said the committee has found the plants growing at elevations as high as 2,000 to 9,850 feet.

The Maui Invasive Species Committee surveys 1,000 acres by ground and 15,000 acres by air.
The Maui Invasive Species Committee surveys 1,000 acres by ground and 15,000 acres by air. Courtesy: Maui Invasive Species Committee

Maui has been working to eradicate pampas grass since the late 1980s. So far, more than 50,000 pampas grass plants from both species have been removed, according to the committee’s data. It’s unclear how many individual plants are left, but Fukushima said the committee visits 125 known sites of pampas grass every year.

Franny Brewer, acting program manager for the Big Island Invasive Species Committee, said the eradication of the plant isn’t necessarily permanent since people can easily obtain the plant online these days. Dried pampas grass also can pose a problem if it’s not dried properly, she said.

“We say it’s gone from Hawaii island, but with invasive species, you can never say never,” Brewer said.

Some Solutions

In addition to the noxious weeds list, groups have been trying to educate the public about the dangers of invasive plants to the local environment.

Plant Pono is a website that provides information on alternatives to promote responsible landscaping and gardening. It also ranks plant species as low or high risk of becoming invasive to Hawaii.

The website is a partnership between the Hawaii Invasive Species Council, the Coordinating Group on Alien Pest Species, the Hawaii Biological Information Network and the Landscape Industry Council of Hawaii.

The Plant Pono website gives users a chance to look at plants that are harmful or less harmful for the environment. .
The Plant Pono website gives users a chance to look at which plants are harmful or less harmful to the environment. Screenshot: Plant Pono

“It’s just a way to further educate people,” Fukushima said. “We’re not trying to accuse or lay down the law. We’re just trying to work with our communities, so they’re not bringing these things in.”

Fukushima emphasized that Hawaii has so many native plants as well as noninvasive plants to use as decor. She recommends using sugarcane as an alternative to pampas grass since they have similar features.

Rogg, meanwhile, said that once a new noxious weeds list is finalized, he intends to review it every year.

“That’s something I want to get to eventually – that we review some of these rules on a regular basis, not every 30 to 40 years. Because things in science change, so we can do housekeeping,” he said.

Hawaii Grown” is funded in part by grants from the Stupski Foundation, Ulupono Fund at the Hawaii Community Foundation and the Frost Family Foundation.

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