Gymnosporangium cornutum, a rust fungus known as the Juniper rust

Gymnosporangium cornutum, a rust fungus called the Juniper rust, growing on a leaf of Rowan, Sorbus aucuparia

FinlandGymnosporangiumGymnosporangium cornutumJulyJuniper rustSorbusSorbus aucupariaashaucupariaclavariformecolorfulcornutumdiseasefirefungifungusheteroecioushostinfectionjuniperleafmountainmountain ash juniper rustoforangeparasiteparasiticpihlajapihlajankatajanruosteplantplant disease fungal infectionplantpathogenicrowanruostesienirustrust fungustongues