Studies of the life cycle of Gremmeniella abietina on Scots pine in southern Sweden

Aspects of the life cycle ofGremmeniella abietina(Lagerb.) Morelet were studied from 1988 to 1990 in stands ofPinus sylvestrisL., 16–32 years old, in southern Sweden, initiated in 1988 with a widespread outbreak of the disease. Pycnidia started to release conidia in late spring and apothecia began to release ascospores in summer. Latent infections could still be detected one year after their establishment by cultivation of healthy looking shoots on agar petri dishes.G. abietinaappeared to have a mainly biennal life cycle, as most spores were released two years after infection of the shoot.