|Petrović Ljubomir, Mihajlović Novak|
|The role and tasks of engineers and technicians of forestry and timber industry in the further development of the communal systemas well as in the futherance of the forestry and timber industry PDF||193|
|Organization of modern forest production (forestry) and new achievements in science and engineering. PDF||198|
|Argyresthia fundella F. R. — A moth of Fir needles — the causative agent of the dying back of Fir in Gorski Kotar. PDF EN||203|
|Summary: Thus far the Fir needle moth (Argyresthia fundella F. R.) was considered in Croatia an insignificant insect pest. In the last years it has multiplied to such numbers in the area of the Fužine forest district (in Gorski Kotar) as to cause serious damage to the forest economy. Owing to this insect pest a large number of Fir trees have died back and have been felled - according to incomplete data - totalling a volume of over 12.000 cu. m.|
The favourable climatic conditions round Fužine - exposed to the influence of Mediterranean climate, which in the last years has become warmer - has helped multiplication of this insect pest.
The biological data on the Fir needle moth occurring in our regions are - some small variations excepting - in harmony with those already known in literature. In Gorski Kotar the built-up of the population ("gradation") started already in 1950 and ended in 1957. During this period the infestation was spreading more and more, occupying new forest stands every year. Intensively attacked were ca. 400 ha., the whole of the area amounting to ca. 1000 ha. Above an altitute of 1000 m. Argyresthia does not occur, which, too, proves that its occurrence is conditioned in the first place by climatic conditions.
Damages by the Fir needle moth manifest themselves in dying away of trees as well as in the loss of increment. The loss of increment because of the poor capability of Fir to regenerate the crown extends over several years. In Gorski Kotar it is still felt to-day after 8 years. Some trees die back immediately, others vegetate for 8 years and more, dying back at last. The young growth of Fir too. suffers from attacks. The Spruce is not endangered in spite of attacks on single needles during the culmination of the pest outbreak. The attacked Fir trees bear no seeds. Thus there is a risk of deforestation for the soil on a calcareous parent rock.
Experiments of control performed both in the forest and in the laboratory have proved the Parathion E-605 to be effective against larvae in a concentration of 0.1- 0.2 %. Metasystox has given good results in higher concentrations (0.3 %). Systox is ineffective. Cold weather reduces the efficiency of all the mentioned preparations. Owing to this as well as because of the inadequate potency of these insecticides their use in the control is not recommended.
The control of butterflies can be carried out by means of the Swingfog apparatus spraying DDT-preparations (Pantakan M-15). The combating should be started immediately after the emergence of the first butterfly, and then it is to be repeated after 10 and 20 days respectively. For the beginning of the control one should consult the entomologist who will follow up the course of pupation as well as the emergence of the butterfly, and on the basis of this he would determine the time of combating action.
The enormous losses caused by this inect pest to our coniferous forest resources will justify the expenses to be sustained in the control.
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|Juridical considerations from the field of forestry. PDF DE||223|
|An old practical method for the calculation of increment in selection forets. PDF FR||228|
|Some characteristics of the plant community Querceto-Carpinetum Serbicum Rudski. PDF DE||231|
|Effect of gamma-rays on the germinability of certain Conifer seeds. PDF EN||235|