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ŠUMARSKI LIST 12/1959 str. 41     <-- 41 -->        PDF

8. Kr ahl
- Urban (J): Untersuchungen über den Jahrringbau der Eichen im
Preuss. Forstamt Freienwalde, Verlag J. Neumann-Neudamm, 1939.
9. Krahl-Urban (J): Die Eichen, Berlin 1959.
10. Tredelenbur g (R): M. Mayer-Wegelin, Holz als Rohstoff, München 1955.
11.
Trouvelot (B), Grison (P), Billioti (E): La prevision des infestations de
Processionnaire du Chene eu vue de traitement chimiques. Extrait du proces
verbal de la Seance du 9. Juillet 1952; Academie d´Agriculture de France.
12.
Schobe r (R): Zum Einfluss der letzten Dürrejahre auf den Dickenzuwachs
Forstwissenschaftliches Centralblatt, 70 Jahrg. Heft 4, April 1951.
ECONOMIC AND BIOCOENOTIC EFFCTS OF LATE TREATMENT OF STANDS
AGAINST THE GIPSY MOTH (LYMANTRIA DISPAR L.)


SUMMARY


In the forests of the Lipovljani district, which, in 1950, were totally defoliated
by the Gipsy Moth (Lymantria đispar L.) K1 e p a c established a loss of SO10/!) of the
total annual increment. Meanwhile, in 1957, these forests were treated by aerial
mist-spraying, and therefore no loss of increment was expected. But in this year,
too, K1 e p a c established a loss of 40´Vo of the total annual increment. In his work
the author interpreted this phenomenon. The author states that the spraving in the
before-mentioned forests was carried out too late so that before being destroyed
the caterpillars already reduced the chlorophyll apparatus which remained in such a
reduced condition up to the end of the growing season, i. e. almost 3 months (fot. 5).


In case of complete defoliation trees regenerate their foliage after 20—25 days,
(fot. 3 and 4). Owing to this also the increment was less reduced. The author established
that a loss of 4ö°/o of the totale annuel increment in 1957, cannot be ascribed
to the climatic conditions, comparing the average annual increment of the 1951-1955
period with that of the year 1957 by availing himself of SCHOBER´s investigations
on the influence of dry years on the increment of different tree species.


The author concludes that a late spraying has no justification because the
desirable objective i. e. to save the increment is not attainable. Especially in the
years when a natural decrease of the infestation can be expected a late spraying
has no justification. Besides, when a late spraying is applied there occurs a destruction
of the useful entomofauna which can give rise to a stronger activity of
other forest pests having common parasites with Gipsy Moth.


The
author recommends that an early spraying with chemicals should be


applied, and that rationally.


(Primljeno za štampu VIII. 1959.).