We carried out the comparative analysis of phytotoxic effect of BI-58 pesticide on morphometric indicators of roots of seeds of Zea mays L. and Allium cepa L. Results of the conducted research showed that BI-58 in the range of the studied concentrations (0,05 - 0,4 ml/l) had the negative impact on sprouts of Allium cepa and Zea mays' seeds which is shown in inhibition of a root gain and viability of seeds. This influence had the expressed dose-dependent character: increase of concentration of the tested preparation caused decrease in the studied indicators in both test cultures. The dose of 0,05 ml/l of phytotoxic action didn't render on sprouts of Allium cepa and Zea mays. It should be noted the concentration of BI-58 recommended for application (0,1 ml/l) had the expressed phytotoxic effect on test plants. It was established sprouts of Zea mays were more sensitive to toxic effect of pesticide, than Allium cepa. On the basis of these data this dose at cultivation of the tested cultures was recommended not to use. The further increase in concentration of BI-58 (0,2 and 0,4 ml/l) caused the interfaced increase of phytotoxic effect on Самарский научный вестник. 2015. № 2(11) 136 Д.Э. Эмирова СКРИНИНГ ФИТОТОКСИЧЕСКОГО ДЕЙСТВИЯ ПЕСТИЦИДА БИ-58 ... the tested cultures. Length of roots of Allium sera decreased by 1,5 times at concentration of 0,2 ml/l and by 40,66% - at decrease in quantity of the sprouted seeds. The increase in concentration of a preparation (0,4 ml/l) caused decrease in length of roots of sprouts of the studied test culture and oppression of their viability. In particular, length of roots of Allium sera in this option of research decreased by 1,8 times in comparison with control, a viability indicator - by 46,16%. Pesticide had similar impact on Zea mays. In particular, at a dose of BI-58 of 0,2 ml/l length of backs of Zea mays decreased by 45,1%, a viability indicator - for 25,3% in comparison with control. The increase in concentration of the studied preparation twice (0,4 ml/l) caused decrease of the morforometric roots indicators for 52,1%, decrease in viability - for 28,8% in comparison with control option.