Research Information System
Forest Pathology, vol.30, no.4, pp.185-193, 2000 (SCI-Expanded, Scopus)
Colonization of living Norway spruce needles by Lophodermium piceae was studied in southern Sweden. One-month to 3-year-old needles were assessed for frequency of infection. Needles appearing in the growing season of 1996 were monitored and sampled at 1 to 4 week intervals over a period of 14 months. Infection frequency of the current-year needles increased from around 20% in July to approximately 40% in August 1996. This level had then doubled to approximately 80% after another growing season in August 1997. Multiple infections were rare in the needles during the first growing season, but after the second growing season at least 70% of the needles had multiple infections. The average number of infections in 9-, 21- and 33-month-old needles were 1.3, 6.3 and 8.4, respectively. The size of the individual mycelia was estimated to be small in all needles, none of the individuals could be isolated from more than two adjacent needle sections, about 1.5 mm long. In conclusion, the number of L. piceae infections per needle increased during ageing of needles but mycelial growth is probably postponed until needle senescence and death.