Current issue: 55(3)
Under compilation: 55(4)
The effect of three pesticides containing either dimethoate (0.5% a.i.), permitrin (0.5%) or triadimephon (0.5%) on the cone pests and flowering biology of Norway spruce (Picea abies (L.) H. Karst.) was tested in a seed orchard in mid-May or in the beginning of June. The pesticide treatments significantly reduced infestation by Laspeyresia strobiella and Kaltenbachiella strobi only. Variation in the number of cones infested by both insects and cone rusts was high between the spruce clones. Generally, the pesticides did not affect flower viability, seed quality or seed germination, but reduced drastically the germination capacity of pollen in vitro. In practice, sufficient control cannot be achieved with concentrations or methods used in the present study.
The PDF includes an abstract in Finnish.
This review discusses whether forests are affected by biotic damages due to present or future environmental disturbances, and do environmental threats, such as air pollution and climatic change, weaken the condition of forest in a way that makes them vulnerable to damages by fungi and insect. The defence mechanisms of trees and factors affecting the development of an outbreak are described. Finally, the ways that air pollution and climatic change may affect biotic damages are discussed.
The effect of nitrogen fertilization and two insecticides on the occurrence of the plant pine bark bug, Aradus cinnamomeus Panzer, was investigated in a young Scots pine (Pinus sylvestris L.) stand in Southern Finland. Three years after the treatment the bug density was lowest in the trees treated with lindane or dimethoate. However, in spite of the increasing height growth of the trees, they did not grow significantly faster than the control trees. Nitrogen fertilization increased both bug density and the height growth of the trees. Thus, the value of nitrogen fertilization against Aradus cinnamomeus remains obscure.
The PDF includes a summary in Finnish.