Phragmidium violaceum - Blackberry plants infected with rust fungus, a biological control agent for blackberry. The newly released strains of the European blackberry rust fungus (<i>Phragmidium violaceum</i>) are highly host-specific for weedy blackberries. © division, CSIRO - CC BY 3.0 - Wikimedia Commons
Foret de Cerisy - Forêt de la Massane