Zea mays originate from warm and tropical region of the world and needs high sum of effective temperature throughout vegetative period. On the Polish market varieties of maize differ in early maturing, provenance and temperature requirements. The foreign varieties react stronger to the sulfonylurea herbicides (nicosulfuron, rimsulfuron, foramsulfuron + jodosulfuron) than Polish maize varieties under unfavorable weather conditions. The trials were conducted in field conditions using 8 maize varieties. The aim of this experiment was evaluation of the influence of sulfonylurea herbicides on foreign and Polish varieties of maize under different weather conditions. The reaction of foreign maize varieties on herbicides was compared with reaction of Polish maize varieties in the years 2001-2002. Four early maturing varieties of maize were testing: AVENUE (FAO 220)-FR, JANNA (FAO 190)-USA, WIARUS (FAO 220)-PL, FIDO (FAO 220)-PL. It was proved that Polish maize varieties showed a higher toleration towards sulfonylurea herbicides. The later maturing varieties KRÓL (FAO 280)-PL, IMAN (FAO 300)-PL, KANZLER (FAO 300)-FR, MAGISTER (FAO 280)-CH responded in a similar way. In 2002 there were no differences in plant development between foreign and Polish maize varieties.

The aim of trials was to determine the efficacy of three doses of herbicides in different weather conditions. There were tested two herbicide groups: hormon type herbicides and sulfonylurea herbicides. Each of the herbicide (Aminopielik Gold 530 EW, MCPA 750 SL, Duplosan Super 600 SL, Granstar 75 WG, Grody! 75 WG, Lintur 70 WG) was applied in three doses: recommended dose, 1/2 of recommended dose and 1/4 of recommended dose. The herbicides were applied in the tillering stage of spring wheat. In some cases it is possible reducing doses of herbicides but decision about choice of herbicide type and dose should be considered in connection with weather conditions before application.