Articles
STRESS FACTORS OF URBAN TREES AND THEIR RELEVANCE FOR VIGOUR AND PREDISPOSITION FOR PARASITE ATTACKS
Article number
496_40
Pages
325 – 334
Language
Abstract
In the city of Basel the influence of various site conditions, nutrient status and air pollutants upon vigour and parasite attacks with avenue trees were studied over a period of fourteen years from 1984 to 1997. Site studies revealed that the main tree species such as Acer, Aesculus and Tilia grown in small tree grids with restricted soil volume and poor water conditions show a significantly increased crown thinning compared to trees in large borders.
By changing the small grids into borders, trees recovered after some years.
However, Tilia in small tree grids were significantly more infested by aphids (Eucallipterus tiliae), spider mites (Eotetranychus tiliarum) and sawfly slugs (Caliroa annulipes). London plane recently stressed by road construction work close to their root space often leading to root injuries showed a significantly increased attack by lace bugs (Corythucha ciliata) compared to undisturbed individuals.
Nutrient analysis revealed wide ratios of N/P, N/K and N/Mg.
Disease incidence of Guignardia aesculi on Aesculus was positively correlated with wide ratios of nitrogen to phosphorus in the leaves and the infestation of Tilia by the gall mite Eriophyes leiosoma with high ratios of nitrogen to potassium.
In various experiments with open top chambers with filtered and non filtered air, pollutants such as NOx and O3 changed the host parasite relationship, resulting in anF increased or decreased attack by pests or pathogenic fungi.
By changing the small grids into borders, trees recovered after some years.
However, Tilia in small tree grids were significantly more infested by aphids (Eucallipterus tiliae), spider mites (Eotetranychus tiliarum) and sawfly slugs (Caliroa annulipes). London plane recently stressed by road construction work close to their root space often leading to root injuries showed a significantly increased attack by lace bugs (Corythucha ciliata) compared to undisturbed individuals.
Nutrient analysis revealed wide ratios of N/P, N/K and N/Mg.
Disease incidence of Guignardia aesculi on Aesculus was positively correlated with wide ratios of nitrogen to phosphorus in the leaves and the infestation of Tilia by the gall mite Eriophyes leiosoma with high ratios of nitrogen to potassium.
In various experiments with open top chambers with filtered and non filtered air, pollutants such as NOx and O3 changed the host parasite relationship, resulting in anF increased or decreased attack by pests or pathogenic fungi.
Publication
Authors
W. Flückiger, S. Braun
Keywords
Site factors, parasite attack, Acer platanoides, Aesculus hippocastanum, Tilia euchlora/cordata, Platanus x acerifolia
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