出版社：Forestry Commission of the Hungarian Academy of Sciences
摘要：Gremmeniella abietina type A caused two widespread epidemics in Nordic countries: in 1982 in Finland and in 2001 in Sweden. The reasons for these epidemics are discussed based on the inoculation experiments in Finland and the literature. The fungus has been inoculated by putting a piece of mycelium in the phloem or by spraying the conidia or ascospores on pine shoots. Mycelial inoculations cause cankers in dormant period inoculations, but not in summer inoculations. During the dormant period, pine cannot actively defend against the fungus. Spore inoculations are successful in summer, which is also the natural spreading time of the fungus. The reason for infection seems to be poor structural resistance in infected shoots. Firstly the fungus infects the bract and during the dormant period it grows to the phloem through poorly developed cork layers between the dead bract and living phloem. A serious epidemic needs a rainy and cloudy summer and also the same kind of summer two years before. A mild winter enhances the growth in cankers, but a mild winter alone cannot cause the epidemics. Gremmeniella abietina damage is controlled by using local or a little bit of northern provenances
