Response of weedy sunflower populations (Helianthus annuus L.) to imazamox and nicosulfuron

Weedy sunflower, Helianthus annuus L. is an economically very important, invasive species widely distributed in many regions of the world, especially areas where sunflower hybrids tolerant to some als-inhibiting herbicides are intensively cultivated. The discovery and development a new technology cultivated increased emergence resistant biotypes due high selection pressure spontaneous hybridisation (transfer genes responsible for tolerance from crop wild species). This study examined responses two populations weedy (HELAN 1 HELAN 2) nicosulfuron imazamox bioassay under greenhouse conditions. experiment included five treatments with different application rates (12, 24, 48, 96 192 g ha-1) (10, 20, 40, 80 160 that were applied over plants at their growth stage 2-3 pairs developed leaves. In addition visual assessment plant damage, which was performed 7, 14, 21 28 days after herbicide application, following parameters also measured: fresh dry weight. obtained results indicate changes sensitivity als inhibitors. Reduced 2 suggests possible Surčin area.