Wplyw spoznionych przymrozkow oraz owadow na zdrowotnosc szyszek modrzewia europejskiego Larix decidua Mill.

Results of the study on impact of the late ground frost on cones of Larix decidua Mill. and cono- and seminiphagous insects: Strobilomyia laricicola (Karl) and Megastigmus pictus (Först.) are given. On 120 twigs, each 1 m in length, the distance of cone from twig apex was measured. It was determined which cones were not damaged by frost, and which were dead. The data obtained were subjected to a statistical analysis using the Kolmogorov-Smirnov's test, Stu­dent's t-test and U Mann Whitney's test. No unequivocal correlation was found between position of a cone on the twig and the effect of low temperature. The late ground frost destroyed 218 cones (61,6%) of a 357 analysed. It was found that the mature cones (not destroyed by the late frost) often (56,1%) were inhabited by S. laricicola. Seeds extracted from these cones, were dissected, and it was found that seeds were infested by M. pictus. This seminiphagous insect destroyed from 0,6% to 7,2% of seeds (3,3% of 3000 analysed). The cones were collected in southern Poland from 30 larches on six localities (5 in each loc.) in a national park, seed plantations and in a managed stand during the growing season of 2001.