Decay resistance of Siberian larch wood against brown rot fungus. - Part 3. The variation between plus trees and their grafted clones
H Viitanen, L Paajanen, M Venäläinen, A Harju, P Velling
The aim of the study was to estimate the variation in the decay resistance of Siberian larch (Larix sibirica Ledeb.) wood using mature plus trees and their grafted clones. Samples were collected with an increment core borer from 11 original plus trees and their 25-year-old grafted seed orchard clones. A typical brown rot fungus, Coniophora puteana (Schum. ex Fr.) Karst. (BAM Ebw. 15), was used as the decaying organism. The mass loss after 6 weeks' incubation was observed. The results showed that the fast growing wood of the grafts was more susceptible to decay than the wood of the original plus tree. The results showed also radial variation within the mature plus tree logs: the inner part of the heartwood was more susceptible to decay than the outer part of the heartwood. The main advantages of decaying the increment core samples were the possibilities to study standing trees, and to screen large numbers of samples at reasonable costs.