sdu faculty of forestry journal special edition 2009 - Orman Fakültesi

SDÜ ORMAN FAKÜLTESİ DERGİSİ
cotoneaster and Japanese cheesewood, and their importance was lower in European
spindle, with an affected 10.5%. The latter species was affected by powdery
mildew in more than 70% of the SYGs where European spindle was found. This
disease is induced by the fungi Microsphaera euonymi-japonici and it has a high
incidence among this species in cold areas of the Iberian Peninsula (Villalva
Quintana, 2005).
4.7 The most damaged vine species is ivy.
Ivy (Hedera helix) is the most affected vine species as well as the most
abundant vine. Its most frequent problems are dead plants and sunburn lesions on
its leaves. Sunburn lesions appeared because, even though it is a shade tolerant
species which grows in the understorey layer in nature, in many of the cases it grew
in green spaces under full sun situations.
4.8 Biotic diseases are encountered less frequently than abiotic in trees,
although the result was the opposite in shrubs.
In this survey, biotic diseases were due to organisms such as viruses, bacteria,
pests and fungi. On the contrary, abiotic diseases consisted of problems caused by
meteorological and physical agents, by human activities and, by other factors
whose origin is a priori unknown, such as cracks, stem wounds, tumours, etc. Dead
plants were not included in any of the former types.
In trees, abiotic diseases comprised about 60% of total disturbances in each year
(Table 6). The mayor contributions to the high incidence of abiotic diseases are due
to stem wounds, dead branches and epicormic shoots, since they are the most
frequent problems for trees. Similar results were also obtained in a survey in
Quebec (Rocray, 1983).
Table 6. Percentage of abiotic diseases of the total of disturbances. In each year in trees
and shrubs of all the inventoried green spaces.
% of abiotic diseases 2005 2006 2007 2008
Trees 58.8 69.1 56.6 79.7
Shrubs 19.7 47.9 27.6 23.7
The principal problem in green spaces is the abiotic stresses when they are
compared with biotic diseases. This fact should lead to the consideration of the
maintenance and conservation practise which is being applied mainly to the
vegetation of green spaces, because most damages could be avoided if some
recommendations were followed. Various efforts were observed about this issue in
this survey, for instance, the use of stakes and tree shelters in new plantations,
however, in many cases, the achieved effect was just the opposite of the expected
one, since stems were leaned and the friction between the trunk and the object
caused the wounds which were intended to be avoided. Not only the staff in charge
of the conservation of green spaces are responsible for these problems, but also the
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