Xylem sap flow on Norway spruce (Picea abies [L.] Karst.) after inoculation with the bark beetle transmitted blue-stain fungus Ceratocystis polonica : Forest Ecosystem Restoration. Ecological and Economical Impacts of Restoration Processes in Secondary Coniferous Forests

2000

S. 151-153

9 Lit. Ang.

Unselbständiges Werk

200072902

In a field experiment the sap flow of Norway spruce (Picea abies [L.] Karst.) was measured in response to inoculation of Ceratocystis polonica, a virulent fungal associate of the spruce bark beetle Ips typographus. In May 1999, four vigorous, mature Norway spruce trees were mass inoculated with C. polonica at a density of four inoculations per dm¬ in a 120 cm wide band on the lower bole. Two other trees were inoculated with sterile agar and served as control. Sap flow on the six trees was measured with the thermal dissipation method over a period beginning three weeks prior to inoculation until 155 days after inoculation. In three trees that have been inoculated with the fungus, sapwood conductivity decreased dramatically within four to seven weeks after incoculation and virtually no sap flow was measurable on these trees 30 to 50 days after inoculation. Sapwood conductivity in the fourth tree that had been inoculated with C. polonica did not differ from the control trees until late in the growing season, which may indicate a high level of resistance of this tree. The results confirm the ability of C. polonica to kill mature Norway spruce trees and give support for the hypothesis that this fungal associate is mutually assisting its insect vector in overcoming the defence mechanisms of the host tree.