Der Einfluß von Fluorverbindungeii auf den Chlorophyll a+b-Gehalt von Pappelblättern im Freiland bei verschiedener Belastung1

The effect of different concentrations of fluorine on the content of chlorophylls a and b in poplar leaves. The concentrations of the chlorophylls a and b and of the fluoride ions in poplar leaves were measured regularly from May to September 1974. The concentration of F increased steadily whereas the concentration of the chlorophylls decreased by 30% compared to first appearance of the leaves. The content of F- to that of chlorophyll a and b cannot be correlated.     

Der Nachweis unsichtbarer („physiologischer”) Fluor-Immissionsschädigungen an Waldbäumen durch eine einfache kolorimetrische Bestimmung der Peroxidase-Aktivität

The detection of hidden F-injury of forest trees by a simple colorimetric determination of peroxidase actívity . The paper describes a simple routine method for determining colorimetrically peroxidase activity (p. a.) in foliage of forest tree species, including conifers. The effect of factors such as foliage age, F Content, external F dust, necrosis etc. on p. a. is investigated. Analyses of plants exposed at different distances to F exhalates of an aluminum plant show that with decreasing distance F content and p. a. increase. P. a. thus is an indicator of air pollution effects on tree physiology even in the range where no visible symptoms of injury occur.     

Untersuchungen zur Abhängigkeit der Buchen-Rindennekrose von der Stärke des Befalls durch Cryptococcus fagisuga in Buchen-(Fagus sylvatica-)Wirtschaftswäldern

Investigations into the dependence of beech bark necrosis on infection with Cryptococcus fagisuga in commercial beech-(Fagus sylvatica)forests. Occurrence and sequence of attack of Fagus sylvatica by Cryptococcus fagisuga, slime flux, and necrosis were followed with four different methods of observation. Under average climatic conditions provocation and development of individual successive infection waves overlap to such a high degree that, because of the relatively short duration of the scale attack and because of the long duration and the great variation of the intensity of the necrotic reaction of the susceptible members of the beech population, individual waves of attack can hardly be discriminated in time and space.     

Die Wirkung wäßriger Streuextrakte verschiedener Waldbäume auf Mycelwachstum und Konidiosporenkeimung von Fomes annosus (Fr.) Cke.

The effect of water extracts of leaf and needle litter from different forest trees on the mycelial growth and the germination rate of conidia of Fomes annosus (Fr.) Cke. Litter extracts from various forest trees and stands have distinct effects on mycelial growth and germination rate of conidia of Fomes annosus. The effects depend on concentration of the extract, period of extraction and on date of collecting the litter samples.     

Über die Ursachen und Kriterien der Immissionsresistenz bei Fichte,Picea abies (L.) Karst1

Causes and criteria of resistance to air pollution in Norway spruce. 1. Morphological and anatomical resistance. Pollution resistance of selected visibly resistant clones is not due to environmental causes or to length of the growing season. Between the resistant and other clones there are significant differences in morphology and anatomy of the needles. The average length, width and weight of the needles of resistant spruce grafts arc greater than those of none resistant. The resistant grafts have more stomata and, at least in winter, lower permeability of needle tissue to gases.     

Experimente mit Erregern der Umfallkrankheit

Experiments with fungi causing damping off. II. Infections of conifer seedlings of different provenances with one or more damping-off fungi and Triclioderma viride Pers. ex Fr. Provenances of native conifer seedlings show varying susceptibility to the agents of damping-off. Following infections with damping-off fungi together with Tricboderma viride increased disease symptoms often appeared. Thus the antagonist seemingly increases the susceptibility of the treated seedlings.     

Untersuchungen über die Salzverträglichkeit verschiedener Pappel-und Weidenarten sowie -klone unter Labor- und Freilandbedingungen

The salt tolerance of various poplar and willow species and clones in the laboratory and field. The resistance of 10 black and 10 grey poplar clones and of 36 willow clones was examined by dipping shoots in a higly concentrated NaCl solution. All the black and most of the grey poplars showed high resistance. Only eleven willow-clones showed sufficient resistance. The studies are to be continued with enlarged material under various ecological conditions.     

Wundfäule in Fichtenwaldungen mit alten Schälschäden

Wound decays in spruce stands following bark stripping . 2083 trees in 91 sample plots on four trial areas (24 ha) were examined for bark stripping and decay. Only 25% of trees showed no injury. Of the injured trees, 73% showed some degree of decay, 10% discoloration. and 17% neither decay nor discoloration. Of the wood destroying fungi isolated Fomes annosus was dominant and appeared to be the most important and widespread of the wound inhabiting fungi in the test area. Besides the Basidiomycetes a considerable number of other fungi was isolated. The most frequent was Cylindrocarpon cylindroides var. tenue.     

Untersuchungen über Potebniamyces coniferarum in den Niederlanden

Research on Potebniamyces coniferarum in the Netherlands . A review of research done in the Netherlands on the fungus Potebniamyces coniferarum, the cause of the Phomopsis disease of Douglas fir and Japanese larch, is given.