FIELD: plant growing, agriculture chemistry, agriculture. SUBSTANCE: invention proposes composition used for protection of plants and method for treatment of plants used in manufacture of plant production. Method involves treatment of plants with indicated composition containing the preparation as a component of special supplements prepared by successive extraction of biomass of micromycetus Pythium ultimum with nonpolar extractant taken in supercritical state, water, alkali, water, acid, water, alkali and water followed by combination of solid residue with the first extract. Plants are treated with composition taken in the amount 0.1-20 mg/ha o planting or 0.5-10000 mg/t of sowing material as measured for the total content of chitosan, arachidonic and eicosapentaenic acids. Invention allows reducing the accumulation of toxic substances in agriculture crops and on soil, their transport and stress effect of toxic substances on agriculture crops also. EFFECT: improved treatment method of plants. 2 cl, 3 tbl, 5 ex
