Mysterious leaf loss affects birch trees in Finland

Birch trees across parts of southern Finland are shedding leaves or failing to develop full foliage this summer, prompting an investigation by the Natural Resources Institute Finland (Luke), which says the cause remains unknown. Researchers have received a surge of reports from members of the public about thinning canopies and sparse foliage on birch trees, particularly in urban areas and alongside roads. According to Luke, the affected trees are most often found along roadsides, in tree-...