Mulberry trees are illegal in some areas primarily due to their environmental impact, health risks, and nuisance factors. The white mulberry tree, in particular, is considered invasive in certain regions because it spreads rapidly, crowds out native vegetation, and hybridizes with native red mulberry trees, which threatens the genetic integrity of the native species. Additionally, birds that eat the mulberry fruits disperse the seeds widely, exacerbating this spread. Health concerns contribute significantly to the bans: male mulberry trees produce a large amount of pollen that can cause severe allergic reactions and exacerbate asthma in sensitive individuals. The sap of white mulberry trees can irritate skin and be harmful if ingested, and unripe berries are also considered a health risk. Mulberry trees also create practical issues such as the mess from fallen berries that stain sidewalks, driveways, and buildings. Their roots can damage property infrastructure like sidewalks and pipes. These combined environmental, health, and nuisance concerns have led cities like El Paso, Las Vegas, Tucson, and Albuquerque, among others, to ban or heavily regulate mulberry trees, especially the white mulberry variety, to protect residents and local ecosystems.
