Saving Elms by Embracing Their Killer

Scientists are now employing the very pathogen that devastated American elm populations to spearhead their restoration. An initiative led by researchers in Vermont is identifying and breeding elms resistant to Dutch elm disease, a fungus that has killed tens of millions of trees over the past century. This innovative approach involves inoculating young elms with the disease to assess their survival rates.

The surviving saplings are earmarked for a seed orchard, a dedicated breeding ground. After approximately 15 years of growth, these trees are expected to produce seeds that will be used to reintroduce resilient elms into forests, riverbanks, and urban landscapes. This effort aims to rebuild the genetic diversity of disease-tolerant elms.

American elms are critical to ecosystem health, particularly their role in managing hydrology in wet regions. Their ability to absorb excess rainfall and tolerate floodwaters makes them essential for mitigating flood damage along river networks. This resilience is increasingly important amid changing weather patterns, including unpredictable droughts and floods.

Meanwhile, a separate initiative is underway to protect ash trees from the emerald ash borer. The Appalachian Trail Conservancy has been injecting select ash trees with insecticide since 2016 to enhance their survival. Unlike the elm program, which focuses on selective breeding, the ash tree conservation relies on ongoing chemical treatments.