The presence of kochia (Kochia scoparia [L.] Schrader) was discovered at three new localities with different histories of imazapyr use. At the locality Jihlava, kochia was resistant to imazapyr and cross resistant to nine sulfonylureas after long-term applications of imazapyr. At Ћiћkov and Karlín most kochia plants were sensitive to all tested sulfonylureas. Plants showed the highest level of resistance to triflusulfuron. Plants of all three populations were sensitive to atrazine. After treatment with all tested herbicides the fresh matter of aboveground parts of the populations at Žižkov and Kolín was reduced in comparison with the untreated control. Treatment with all sulfonylureas and imazapyr caused significant differences in the fresh matter of aboveground parts between the population at Jihlava and those at Karlín and Žižkov.