Finding the Vector

Rapid ʻŌhiʻa Death appeared on Hawaiʻi Island around 2014, killing ʻōhiʻa trees — the most abundant and ecologically important native trees in the Hawaiian forest. The disease spread fast and no one knew how to stop it. Could we map the extent of infection and figure out what was driving transmission?

Flying the affected forests repeatedly, the spectral signatures of infected trees were distinct enough to track disease spread at landscape scale. The breakthrough came from an unexpected pattern. When infection maps were overlaid with land management data, something jumped out. Areas that were fenced AND ungulate-free showed dramatically lower infection rates — one-tenth to one-seventeenth the spread rate compared to unfenced or incompletely cleared areas. Fencing without removal wasn't enough. Feral pigs were rooting through the forest floor, wounding ʻōhiʻa roots and creating pathogen entry points, transporting contaminated soil on their hooves. Only complete exclusion broke the cycle.

The findings were presented to DOA, Forest Service, and National Park Service. Fencing and ungulate removal priorities shifted based on the data. The discovery fundamentally changed how the state approaches ROD containment. This is our home. Watching ʻōhiʻa die across the island is personal. Finding something that helps stop it matters more than most missions we fly.