FIELD: plant growing and agricultural chemistry. SUBSTANCE: method involves treating plants with composition comprising preparation obtained by sequential extraction of Mortierella globulifers micromycet biomass by means of non-polar extracting agent in above- critical state, water, alkali, water, acid, water, alkali, and water, said preparation being used as target additive; joining solid residue with first extract. Plants are treated with said composition 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 decreased stress effect of toxic substances on agricultural crops. 3 cl, 3 tbl, 5 ex
