Incidence of main stem infections of lodgepole pine by western gall rust decreases with tree age

• Published in: Canadian journal of forest research Vol. 35; no. 6; pp. 1314 - 1318
• Main Authors: Blenis, P.V, Li, W
• Format: Journal Article
• Language: English
• Published: Ottawa, Canada NRC Research Press 01.06.2005; National Research Council of Canada; Canadian Science Publishing NRC Research Press
• Subjects: Age; air temperature; Biological and medical sciences; disease incidence; Endocronartium harknessii; forest trees; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; microclimate; Pathology, epidemiology, host-fungus relationships. Damages, economic importance; phenology; Phytopathology. Animal pests. Plant and forest protection; Pinus contorta; Plant growth; plant pathogenic fungi; Plant pathology; Plant resistance; rust diseases; spore germination; tree age; tree growth; tree trunk; Trees; Alberta; Canada; North America; America; Infection modality; Plant pathology; Plant pathogen; Mycosis; Growth; Silviculture; Temperature effect; Pinus contorta; Basidiomycetes; Environmental factor; Microclimate; Epidemiology; Stem; Forest pathology; Fungi; Softwood forest tree; Gymnospermae; Influence factor; Age; Plant height; Thallophyta; Phytoclimate; Pathophysiology; Tree classes; Forest tree; Parasitic rust; Woody plant; Morbidity; Infection; Height increment; Decrease; Vegetative apparatus; Forestry; Concentration effect; Forest thinning; Coniferales; Spermatophyta; Shoot; Inoculum
• ISSN: 0045-5067; 1208-6037
• DOI: 10.1139/x05-059

Infection of lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) by western gall rust has been shown to decrease with tree height and age, but the effects of those two factors have not been separated. Five replicate artificial inoculations were done on a total of 327 trees of different ages in two height classes. Temperature and percentage of spore germination at the height of inoculation, shoot development (stem elongation at the time of inoculation as a proportion of final shoot elongation), main stem leader length at the time of inoculation, tree height, and tree age were measured. Modeled percentages of infected trees and the number of galls per 10 cm of shoot length decreased by 85% and 88%, respectively, as tree age increased between 2 and 10 years, indicating the undesirability of early, aggressive precommercial thinning of lodgepole pine stands in areas where western gall rust is common. By controlling and (or) statistically accounting for inoculum, microclimate, and phenological factors, it was possible to demonstrate that changes in susceptibility with tree age are sufficient to account for the reduction in infection with tree height.