First report of Chrysomyxa ledicola attacking spruce (Picea spp.) in Greenland.
In August 2019, spruce trees in an extensive area in a plantation in Kuusuaq (Tasermiut), Greenland, showed symptoms resembling those of spruce needle rust. The plantation was established from 1960 onwards and covers an area of 5.5 ha with mainly Picea glauca, Picea × lutzii, Pinus contorta and Larix sibirica partly mixed, partly planted in blocks/rows. The infection was observed primarily on P. × lutzii. Symptoms included yellowing of the current year's needles, entire branch systems turning yellow to whitish, and needles being covered by aecia with white papery fracturing peridia. Minor infection was observed on P. glauca with scattered shoots showing symptoms. The most prominent attacks were observed where P. × lutzii was planted in blocks, and in particular where the alternate host Rhododendron groenlandicum (bog Labrador tea) was growing in dense stands amongst the trees. Here, almost all P. lutzii (an area of 1.0 ha in total) were showing symptoms, even to the tops of the trees. The causal pathogen was isolated and identified as Chrysomyxa ledicola based on morphological and molecular analyses. This is thought to be the first record of C. ledicola attacking Picea sp. in Greenland.