Abstract <p>Control systems for opium poppy (<i>Papaver somniferum</i> L.)—an undesirable narcotic-containing plant—must align with the principles of sustainable agriculture. Their priority is using biological agents and reducing the application of chemical pesticides. In the conducted research, the bioherbicidal activity and efficacy of a promising strain <i>A. papavericola</i> 1.39-8 in laboratory prototypes of mycoherbicides applied in combination with chemical herbicides to suppress <i>Papaver somniferum</i> L. were evaluated. Laboratory mycoherbicide prototypes alone caused mortality of up to 35%, and the severity of toxic damage to surviving poppy plants ranged from 24 to 67%: reductions in growth and biomass reached up to 60 and 65%, respectively. A significant increase in efficacy was recorded after a single combined application of a laboratory prototype based on <i>A. papavericola</i> 1.39-8 and sublethal doses of chemical herbicides based on the active ingredients metsulfuron-methyl and metribuzin. Mortality of test plants and losses in growth and biomass reached 99%.</p>