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Orange Rust Threatens Incense Cedar and Pear Trees in Western Oregon

Source: Orange rust infects incense cedar and pear trees across Western Oregon (2025-11-26)

A recent report from the OSU Extension Service highlights a concerning outbreak of orange rust disease affecting incense cedar and pear trees across Western Oregon. This fungal pathogen, *Gymnosporangium libocedri*, has been rapidly spreading, threatening local ecosystems and agricultural productivity. Experts emphasize the importance of early detection and integrated management strategies to curb its impact. In addition to the immediate threat to ornamental and fruit trees, recent studies reveal that orange rust can significantly reduce tree vitality, leading to decreased timber quality and fruit yields. The disease's spread is exacerbated by changing climate conditions, including increased humidity and warmer temperatures, which favor fungal proliferation. Recent facts include: 1. Orange rust has been confirmed on over 150 acres of affected orchards and natural woodlands in Western Oregon since early 2024. 2. The pathogen primarily infects junipers and other conifers, serving as a host for the rust's life cycle, which then spreads to pear trees. 3. OSU researchers are developing resistant tree varieties and exploring biological control options to manage the disease sustainably. 4. The disease can be identified by distinctive orange pustules on the undersides of leaves and bark, with symptoms appearing in late spring to early summer. 5. Climate models predict that orange rust outbreaks could become more frequent and severe in the Pacific Northwest over the next decade, emphasizing the need for proactive management. This outbreak underscores the importance of integrated pest management (IPM) practices, including proper sanitation, resistant cultivars, and targeted fungicide applications. Local farmers and homeowners are advised to monitor their trees closely, remove and destroy infected plant material, and consult with extension specialists for tailored control strategies. As climate change continues to influence disease dynamics, ongoing research and community engagement will be vital in safeguarding Oregon’s forests and orchards from orange rust and other emerging plant diseases.

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