The impact of Sirococcus shoot blight on radial and height growth of Norway spruce (Picea abies) in young plantations

The impact of Sirococcus shoot blight on the radial and height growth of No rway spruce in a young plantation (approximately 20 years old) was investig ated by examining the increment losses for four infection intensities (clas ses). The average diameter at breast height of trees in the lightly damaged class was 72% when compated with the average diameter of the healthy trees , whereas moderately and severely damaged tree classes were 67 and 57%, res pectively. Using tree ring analysis, the development of radial growth over time due to intensity of infection was studied. Height growth of affected t rees was also significantly reduced (up to 43%) compared with the healthy t rees, thus indicating a dramatic impact of Sirococcus conigenus on the grow th of young Norway spruce.