Heterobasidion root rot in Norway spruce

• Main Author: Thor, Magnus
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2005
• Subjects: Not in use; please see Agris categories; Norway; Stump; The Stump; Fennoscandian
• Online Access: https://pub.epsilon.slu.se/729/; https://pub.epsilon.slu.se/729/1/Avh.nr.5_.pdf

In spite of its biological and economic impact on Swedish forestry, root rot caused by Heterobasidion annosum (Fr.) Bref. sensu lato has received no or little attention in forest planning. This thesis summarizes and discusses two experiments involving prophylactic treatment of stumps, and three investigations on the modelling and simulation of root rot in coniferous stands with special emphasis on Norway spruce (Picea abies [L.] Karst.). In 14 previously unthinned stands of Norway spruce, the efficacy of mechanized stump treatments with disodium octaborate tetrahydrate (DOT), Phlebiopsis gigantea (Fr.) Jül. and urea was compared with no treatment of stumps cut in the summer and winter, and with manual treatment. Stump treatment reduced the stump area colonized by H. annosum s. l. by 88-99% as compared with untreated stumps cut in the summer. In terms of colonized stump area, there were neither differences between compounds, nor between mechanized and manual treatments. Sensitivity of root rot antagonist P. gigantea spores to high temperature or pressure was tested in laboratory and field experiments using a mechanized application. The spores withstood 1,600-2,200 kPa for 24 h without losing viability. Spore germination of P. gigantea had an optimum at c. 30ºC. Mechanized application under normal summer conditions in Sweden did not obstruct spore germination of P. gigantea. Functions for predicting the probability of decay in individual trees were developed using logistic regression from data in the Swedish national forest inventory 1983-2001. The functions use data readily available in most stand records, and are recommended for strategic, tactical and operational planning. Models for simulation of disease development were developed based on known facts about the mode of infection and spread of H. annosum s. l. in Fennoscandian coniferous forests. The economic outcomes for a number of stands typical of Swedish forest management were modelled and predicted using the models for H. annosum s. l. dynamics and models for cross-cutting of trees. Stump treatment in thinning and previous final felling was profitable (interest rates 1, 3 and 5%) in pure stands of Norway spruce and in mixed conifer stands in southern Sweden.