Authors: Kurkela, Timo
Journal: Karstenia, Volume 11 (1970), pages 41-45.
Doi: https://doi.org/10.29203/ka.1970.70
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Abstract: “Lachnellula willkommii, the cause of larch canker, and Lachnellula occidentalis on larch in Finland. Larch plantations, mainly in southern Finland, were surveyed to obtain information about the distribution of the larch canker fungus, Lachnellula willkommii (Hart.) Dennis and the related fungus, Lachnellula occidentalis (Hahn & Ayers) Dharne. Larix decidua and L. sibirica are the larches most frequently grown in Finland, and 86 per cent of the plantations included in the survey were stands of these species.
Larch canker was found to be common in southernmost and southwestern Finland. European larch was surveyed in 32 plantations, of which 22 were infected with L. willkommii. Siberian larch was infected in 20 of the 111 plantations included in the survey. Although the disease was present on Siberian larches, it was not very harmful in any locality, since the fungus had only caused cankers on weakened branches. All 3 plantations of American larches (L. laricina and L. occidentalis) that were examined proved to be infected. The East-Asiatic larches (L. gmelini and L. leptolepis) were relatively resistant. There were only 2 infected plantations among the 13 of the former species included in the survey and not one of the 7 plantations of the latter. In the literature there is one record of larch canker on L. leptolepis in Finland (HEIKINHEIMO 1956). Fig. 1 shows the distribution of Lachnellula willkommii on these different larch species in Finland. Lachnellula occidentalis was observed in most of the larch plantations examined, even in the north (Fig. 2).”