FIELD: plant growing and agricultural chemistry. SUBSTANCE: method involves treating plants with composition comprising target additives containing preparation produced by sequential extracting of Mortierella jenkinii micromycet biomass with non-polar extracting agent in above-critical state, water, alkali, water, acid, water, alkali, and water; joining first extract with solid residue. Composition is used in an amount of 0.1-20 mg/hectare of plantation or 0.5-10,000 mg/t of seeding material at the rate of total content of chitosan, arachidonic acid and eicosapentaenic acid. EFFECT: reduced accumulation of toxic substances in agricultural crops and soil, inhibited migration and stress effect of toxic substances upon crops. 3 cl, 3 tbl
