NATIVE RANGE: Alps, Siberia

FIRST FINDING IN SLOVENIA: likely present for over 100 years

PATHWAYS: spontaneous spread

POSSIBLE TO FIND: year-round

DESCRIPTION: This disease can be recognised by yellowish-orange blister-like swellings, 0.5 to 2 cm long, which appear in springtime on the bark of pines. Inside the swellings there are numerous orange spores, which fall out of the fruiting bodies. At other times of the year, only a deformation of infected parts of the trunk or branches is visible as a resin-exuding wound. Spores are carried by the wind to the leaves of various currant species, where a larger number of small, orange fruiting bodies are formed in autumn. In autumn, the dark brown winter fruiting bodies appear.

HOST PLANTS: Five-needle pine species (especially Weymouth pine, Pinus strobus) and currants (especially black currant, Ribes nigra) are susceptible.

STATUS: Widespread throughout Europe.

SIMILAR SPECIES: Cronartium flaccidum, causes pine stem rust. This disease has identical symptoms, but it affects different host plants and is specific to two-needle pines including Scots pine, (P. sylvestris), black pine (P. nigra), Aleppo pine (P. halepensis) and mountain pine (P. mugo)

SOURCE: Field Guide to Invasive Alien Species in European Forests