EN
Field experiments were conducted in two locations in southern Poland in 2008. The aim of this study was to determine the damage and infestation of conventional and Bt maize by the insect pest Ostrinia nubilalis Hbn. and pathogenic fungus Ustilago maydis Unger. Transgenic cultivar (MON 810) showed high resistance to European corn borer infestation and the percentage of affected plants ranged, depended on localization, from only 0.2% to 0.6%, whereas in case of its conventional version the percentage value ranged from 24.5 to 29.5%. Common smut appeared very rarely in both locations, and the highest disease infection was observed in location A on conventional cultivar (4.8%) and significantly lower on Bt cultivar (0.3%). Cob and grain yields were comparable for both cultivars. In case of cob yield the difference in favor of Bt cultivar in location A was 0.67 dt/ha and 0.01 dt/ha in location B, and for grain yield 0.34 dt/ha i 0.02 dt/ha respectively.