Authors: Hintikka, Veikko
Journal: Karstenia, Volume 14 (1974), pages 12-31.
Doi: https://doi.org/10.29203/ka.1974.86
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Abstract: “The infection biology of Armillariella mellea in young pine seedlings is described. E idence supports the view that the bending of seedlings by snow in winter may be one of the main primary causes for the infection of root system& by rhizomorphs. In spruces, infection may take place from the soils by rhizomorphs, as well as from air by spores, or from stumps via root grafts. The external appearance of spruces suffering from heart rot is discussed.
Rhizomorphs occur ery abundantly in forest soils in South Finland, and based on their ability to regenerate after cutting, as well as on their ability to grow under laboratory conditions, the majority of those found in the soil seem to be living and capable of producing new rhizomorphs.
During the summer, freshly cut pieces of unbarked wood were colonized very rapidly in forest humus by rhizomorphs of Armillariella. The sheath-like rhizomorphs grew as fast as 5 mm a day in the phloem. Spruce phloem was infected most easily, pine, larch and birch wood quite easily, Populus, Salix, Sorbus, and Alnus wood more slowly, and wood of Juniperus not at all. When fresh unbarked wood was infected in the laboratory, a similar variation in resistance between tree species was obtained. The influence of temperature, terpenes and cyanogenic glycosides as well as carbon dioxide, on the resistance of different tree species is discussed.
The results are discussed in relation to the conditions existing in forest soils, and the independence of growing rhizomorph tips on oxygen and nutrients may have importance in the colonization of cambium and wood in waterlogged soils.”