Department of plant pathology of University of Helsinki conducted studies in the surrounding forests of Viikki test farm and on the Hyytiälä forest training station to find about occurrence and spore production of pine needle rust.
The damages have been minor. Most often the infection did not cause yellowing of the needles, only individual needles might have dried up. There were no dead young trees.
The spore production was strongest at the more fertile sites, with abundant occurrence of cow-wheat (Melanpyrum spp.). The infection caused more harm on the cow-wheat than on the pines. In many cases the foliage died prematurely. Melanpyrum spp. were more strongly infected on sites with more light. However, there was no difference found with the fertility of the site.
The PDF contains a summary in Finnish.