DIGITALNA ARHIVA ŠUMARSKOG LISTA
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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.). |