Articles by Antti Uotila

Ascocalyx abietina (now Gremmeniella abietina Lagerb.) infects Scots pine (Pinus sylvestris L.) by means of ascospores or conidia. Ascospores are dispersed by the wind, while the conidia are splash dispersed. The infection rate is positively correlated with the number of inocula. The aim of this study was to determine the extent to which G. abietina spreads to the trees surrounding the diseased trees and to find the correct time to perform sanitation cutting.

The results were obtained from Ascocalyx-inventory carried out in a Scots pine progeny test at Loppi, Southern Finland. Three Siberian provenances were totally destroyed, while the Finnish progenies remained relatively healthy. The two rows adjacent to the destroyed plots were inventoried separately.

There were 29.7% more diseased or dead trees in the two adjacent rows than in the rest of the same plots. The difference was statistically significant. The trees had probably been infected by conidia, because the effect of the destroyed plot only extended to the adjacent two rows. Furthermore, pycnidia had mainly developed on the dead shoots.

On the basis of the life cycle of the fungus and the results, the correct time to carry out sanitation cutting is the first winter after the disease symptoms have appeared. If it is done later, the disease could be spread and bark beetles (Tomicus spp.) could propagate in dying trees. Susceptible provenances may spread the disease to surrounding resistant trees owing to the increasing number of spores.

The PDF includes a summary in English.

• Uotila, E-mail: au@mm.unknown

The Scots pine (Pinus sylvestris L.) pruning experiments were established in different geographical regions of Finland. The pines were pruned in 16 different times during the year. Half of the trees were inoculated with conidia of Phacidium coniferarum (Hahn). Annual cankers were produced in the inoculated trees pruned during October–December. The safe pruning season ended in autumn when the five-day mean temperature decreased below +7°C. The unsafe pruning season terminated when the temperature remained permanently over 0°C. Dry-pruned branches were infected only if the phloem had been wounded. The mycelia of the fungus were pathogenic in the phloem in the inoculations made from October to March. The fungus occurred commonly in slash and in pines wounded during the autumn. The fungus has a one-year life cycle.

The PDF includes a summary in Finnish.

• Uotila, E-mail: au@mm.unknown

• Vartiamäki, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: henna.vartiamaki@metla.fi
• Hantula, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: jh@nn.fi
• Uotila, University of Helsinki, Hyytiälä Forestry Field Station, Hyytiäläntie 124, FI-35500 Korkeakoski, Finland E-mail: au@nn.fi