Autumn brings a golden canopy to Seoul, accompanied by a pungent, vomit-like stench from fallen ginkgo seeds that has driven district authorities to slash replacement projects and rely instead on collection nets.
Ginkgo biloba trees account for nearly one in three street trees across the South Korean capital. When pedestrians crush the fleshy outer coat of fallen seeds, the pulp releases butyric acid and hexanoic acid, compounds that produce a foul odor reminiscent of rancid butter and cheesy socks.
Only female trees produce these foul-smelling seeds, prompting district authorities to gradually replace female trees with male ones. However, these replacement efforts have drawn swift objections from environmentalists, The Straits Times reported in November 2026.
In July 2026, the Seoul branch of the Korea Federation for Environmental Movements released a report estimating that at least 792 ginkgo trees would be removed across the city this year under tree-replacement projects.
Warning municipal leaders not to cave in to pressure from a vocal minority, KFEM activist Jo Hae-min stated, “The value of a single mature ginkgo far outweighs a few weeks of bad smell.”
Seoul designated the ginkgo as its official city tree in 1971 to symbolise national development and prosperity, leading to widespread plantings from the 1970s onward. Saplings planted during this era required 15 to 20 years to reach reproductive maturity, making it impossible for planters to distinguish between male and female trees until fruit appeared.
South Korea’s National Institute of Forest Science developed a DNA-based identification technique in 2011, allowing authorities to select male saplings at the seedling stage. Data from the Seoul Metropolitan Government shows nearly 100,000 ginkgo trees lined city streets at the end of 2025, with the proportion of female ginkgo trees falling by 18.5% over the prior four years.
| Metric | Data | Context |
|---|---|---|
| Total Street Count | Nearly 100,000 trees | Recorded at the end of 2025 |
| Female Tree Decline | Down 18.5% | Drop recorded over a four-year span |
| Targeted Removals | At least 792 trees | Estimated by KFEM for 2026 projects |
To mitigate the seasonal nuisance without felling mature trees, authorities are installing funnel-shaped nets on lower branches and deploying mechanical harvesters to clear fallen fruit. Newsis reported on Oct 21 that the Seoul Metropolitan Government clarified that trees were not targeted merely for being female, noting that removal plans accounted for tight spaces where collection nets cannot fit.
Following the public backlash, the city scaled back its replacement programme. Tree removal is now restricted to safety hazards, including trees competing with overhead power lines and those located near busy pedestrian hubs like bus stops and school routes.
Seoul resident Choi Ji-soo expressed mixed feelings about the urban forestry, noting that the fallen fruit soils shoes and creates slippery walking hazards. Expressing her views to The Straits Times, Choi remarked, “I don’t see it as damaging nature, but more of a way to preserve the ecological benefits of ginkgo trees while effectively solving urban issues like severe odour and slipping hazards at the same time,”.
