New Boot Brush Stations Deployed on Oʻahu in Fight Against Rapid ‘Ōhi‘a Death

A new style of boot brush station could hep reduce the spread of a scourge that has wreaked havoc on Big Island ‘ōhiʻa forests.

The new boot brush station was designed by Sean Moura, a wildlife biologist with Hawaiian Electric. Moura took an existing boot brush design and modified it to be more inviting and user-friendly. Hawaiian Electric is stepping up to help reduce the spread of the rapid ‘ōhiʻa death on Oʻahu through the fabrication and installation of the new boot brush station for trailheads.

The concept was to fine tune the design and coordinate the fabrication of six prototype stations by Hawaiian Electric’s Electrical and Welding Services personnel. These custom-built boot brush stations are the first of their kind in Hawai‘i to include a separate dispenser for sterilizing spray and a bench so users can sit down and spray the bottoms and sides of their shoes comfortably.

In collaboration with the state Department of Land and Natural Resources Division of Forestry and Wildlife, the new stations were installed at Hawai‘i Loa, Wiliwilinui, Manana, Waimano, Moanalua and ʻAiea Loop trailheads along with signage. The first boot brush station was installed at the Kamana Nui and Kamana Iki Valleys in Moanalua at the end of March.

Rapid ‘ōhiʻa death is caused by two related non-native fungal pathogens. These pathogens have killed more than a million trees spread throughout more than 185,000 acres of forest on the Big Island and both pathogens are also present on Kauaʻi in limited areas. On O‘ahu, there have been five ‘ōhiʻa trees infected with the slower-acting pathogen that causes the disease, while there have been no detections of the more aggressive pathogen.

To date, there are no known rapid ‘ōhiʻa death trees on Molokaʻi and Lānaʻi, and the only rapid ‘ōhiʻa death positive tree on Maui was discovered and destroyed in 2018.

“Our environmental stewardship efforts at Hawaiian Electric include protecting native endemic species, especially in areas where our utility infrastructure might intersect with their habitats,” Karin Kimura, director of the Hawaiian Electric Environmental Division, said in a press release. “Working together, we can help reduce the spread of invasive species and (rapid ‘ōhiʻa death), and we’re glad to be a part of the effort to protect Oʻahu’s native forests.”

Boot brush stations are not a new idea, however, the expanded design with a modified handlebar and an integrated seating bench is meant to encourage hikers to use the new style of station, according to Moura. He and staff from the Environmental Division will visit the trailheads quarterly during the next five years and replace any boot brushes that are worn out, while the Division of Forestry and Wildlife will be responsible for maintaining the integrity of the stations.

Plant pathologist Lisa Keith and her team at the U.S. Department of Agriculture Agricultural Research Service in Hilo found that 70% isopropyl alcohol kills the pathogens that cause rapid ‘ōhiʻa death.

“We recommend using a boot brush before and after hiking to remove soil that can contain the (rapid ‘ōhiʻa death) pathogens and then spraying shoe soles with isopropyl alcohol to kill any remaining fungal spores,” Keith said in the press release, adding her office collected soil samples from 34 regular boot brush stations on Hawai‘i island and found that 28 of the stations had the rapid ‘ōhiʻa death pathogens. “Even though just a handful of those samples were still viable, this limited study shows that the (rapid ‘ōhiʻa death) pathogens do move around on shoes.”

Funds provided by the state Legislature and USDA continue to support aerial and ground-based surveys and sampling for rapid ‘ōhiʻa death in forests statewide, and the USDA Agricultural Research Service in Hilo continues to process samples to determine the presence or absence of the rapid ‘ōhiʻa death pathogens.

“We want to thank Hawaiian Electric and Hauʻoli Mau Loa Foundation for being good stewards of the forest and for being great partners in our work,” DLNR Chairperson Suzanne Case said in the press release. “With many natural areas seeing a record number of visitors, and with the resumption of interisland travel, DLNR and its partners remind all forest users to clean their shoes, gear and vehicles of any soil and spray with a 70% alcohol solution — before and after visiting the forest.”