Can invasive gorse help reduce food costs on the Big Island?  A UH Hilo study can uncover |  big island now

Can invasive gorse help reduce food costs on the Big Island? A UH Hilo study can uncover | big island now

When Franny Brewer was a teacher, she took high school students to the slopes of Maunakea for service projects.

“We would stop at a patch of gorse and I would hold up a $20 bill and offer it to any student who could make it 10 feet,” said Brewer, now the Big Island Invasive Species Committee’s acting program director. “The boys, in particular, were jumping around, convinced they were going to get that $20.”

An ongoing study by UH Hilo would analyze how pigs grow on feed made from invasive gorse compared to traditional feedstocks that are expensive due to high shipping rates. Photo by Nathan Christopher/Big Island Now.

However, once the students got close and saw the density of the impenetrable, woody, yellow-flowered shrub — and all the thorns covering it — “most turned around without even trying,” Brewer said.

gorse, or European Ulex, has been listed among the world’s 100 worst invasive alien species by the International Union for Conservation of Nature. It can grow over 10 feet tall and live for up to 30 years. Patches of gorse have already taken over thousands of acres of former pastures on the Big Island and could take on more as they are extremely hardy and resistant to almost any attempt at control, including herbicides.

But at the University of Hawai’i at Hilo Farm in Pana’ewa, between Hilo and Kea’au, a new study is underway that would attempt to eliminate the scourge of gorse by investigating whether it could make a viable feed for livestock.

gorse, or European Ulex. Photo from Wikimedia Commons.

The aim would be to determine how gorse would compare to more traditional commercial feedstocks such as corn, soybeans and alfalfa, for which livestock farmers on the island pay an additional premium due to shipping costs. .


“The state, the nation, the world discovered decades ago that it’s cheaper to ship animals for food than animal feed,” said Nick Krueger, Integrated Systems Instructor of crop raising at the UH-Hilo College of Agriculture, Forestry, and Natural Resources.

As an example, a square bale of alfalfa that would cost $8 to $12 on the mainland, perhaps even as low as $5, costs $50 on the Big Island, he said.

Although the study is only tentative, it recently received a boost in the form of a $500,000 grant approved in October by the Hawai’i County Council. The money will be used by nonprofit organization Hui Ho’olako For Hawaiian Initiatives, a study partner, to harvest gorse from Maunakea, renovate the feed mill near Pana’ Farm ewa of UH-Hilo and lead the study.

The study plan involves UH-Hilo swine production students under Krueger raising two groups of weaned piglets to market weight, over a four-month period early next year. . One group would be fed traditional commercial raw materials while the other would receive a feed made from pulverized gorse cleared from Maunakea areas.

The study would analyze how the pigs grow in each group to find out if those fed the gorse grow as fast and as big as those fed the traditional raw material.


“So if animals can basically gain weight on this feed, then it will be a viable feed and [gorse] will be another material that can go into the feed supply component of the market and hopefully lower the price of livestock feed,” Krueger said.

He added that if a gorse feedstock proves viable and can even begin to reduce feed costs, especially while helping control an invasive species, it would be a win-win.

The island’s small livestock farmers, who Krueger says are suffering from high feed prices, would benefit most from any additional raw material that could be produced here.

Krueger knows there is a ton of gorse readily available on Maunakea, and with a high capacity feed mill nearby that has been sitting idle for years that would be used to make the gorse feedstock pellets. for the study, the potential is there for mass production if it proves to be a viable option.

“Why not try it? Let’s see,” he said.


Gorse is native to Italy, Corsica, Spain, Portugal, France, Switzerland, Germany, Great Britain, Ireland and the Netherlands. The thorny shrub was likely introduced to Hawaii around the turn of the 20th century and was considered an invasive weed in 1925.

According to a Hawai’i Gorse Task Force report to the Hawai’i Legislature in January 2021, gorse occupies at least 10,000 acres of former pasture between 5,000 and 8,000 feet elevation in Humu. ‘ula and Pi’ihonua on Maunakea. Because the infestation is not effectively contained, it is possible for the plant to spread around the island and become established at elevations of 3,300 to 8,000 feet.

“Areas within this elevation range with suitable soils and conditions for gorse could include up to 500,000 acres on the island of Hawaii alone,” the report states.

Brewer said people have been trying to solve the gorse problem for decades.

“Several biocontrols have been launched,” she said. “There have been other attempts to use gorse for commercial ventures over the past decade that we have been contacted about, as biochar or as biofuel. I haven’t heard anything about it for a moment, so maybe they didn’t work.

The gorse eliminates all other plants in its path.

“The only way to get rid of it is to bulldoze it, but the seed bank has an incredibly long lifespan, so you’ll keep regrowing everywhere,” she said. “The plant is also fire-adapted – in fact, the heat encourages the plant to shoot seeds several feet away.”

Brewer said the Big Island Invasive Species Committee always supports efforts to use widespread invasive species to produce value, as long as the production of those resources doesn’t spread the plant.

“There are literally thousands of acres of gorse on Maunakea and that land has been rendered almost worthless for either production or ecosystem services – it can’t be used as livestock fodder, it doesn’t provide any habitat. to native birds and insects, they work against the health of our watershed,” she said.

Krueger explained that by pulverizing the gorse into almost a powder to produce the raw material for the study, it would remove the viability of all the seeds. UH-Hilo and its partners in the study, including the ranches that would clear and supply the gorse, would take great care not to accidentally propagate the gorse.

“Hopefully we can get some of that nasty gorse off the slopes of Maunakea and turn it into viable livestock feed,” said Glenn Sako, economic development specialist for agriculture at the Department of Research and Development. Hawai’i County development.

He spoke at the September 20 meeting of the Council’s Finance Committee at which the resolution for the grant was presented.

Council members agreed that if gorse feedstock proves to be a viable option, it could be a game-changer.

Finance Committee Chair Matt Kaneali’i-Kleinfelder said, “I see this as a potential stepping stone to really making progress toward the sustainability of our food and projects like this on the island of Hawaii. I think gorse would just be the start.

Krueger said hats off to the Council for funding a study that could provide a common-sense solution to tackling the gorse problem and hopefully find a more affordable raw material option for growers on the island.

He also loves that the study gives his students exposure to agricultural and ranching research right here on the Big Island that they wouldn’t otherwise have. It would also take them beyond square one in agricultural science of simply raising animals. It is about what can be improved and the ability to identify objective differences in management.

“It takes it to the next level from, OK, it’s the treatment of piglets, you notch the ears, you cut the teeth, great, great, and it turns into, OK, what’s the standard deviation of this experimental group compared to this, okay? Is there a significant difference?” Krueger said. “And it really exposes them to higher-level science that is useful for doing good in our communities and deepen scientific knowledge.

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