Weeds are always a serious problem in agriculture. Depending on the type of product and weed, wide ranges of fighting methods have been utilized and consequently, it is associated with different harmful economic and environmental effects in different countries. Sinapis arvensis is a common weed with the ecumenical expansion causing performance reduction of many crops, especially wheat. In comparison to the other methods, the biological control method is more efficient. In this study, 4 strains of pea pesto-stricken farms, were isolated from Iran (Lorestan) with the aim of biological control of the Sinapis arvensis weeds. The effects of 50 µl /cm2 produced supernatant of 7 days cultured fungal biomass that was purified by filtration were assayed, on the goal plant in laboratory and research greenhouse, three-fold and according to numbering method, the most necrotic was related to IRLM.LC34 strain, because destructive effects were appeared as necrosis on leaf, stem and finally lead to the death. Therefore this strain was selected for further study. Since the strain was native, the supernatant was inspissated using ammonium sulfate, as a result, causes severe destructive effects on the plant. The protein purification using FPLC showed the presence of the main part containing a protein with about 24 kDa. The direct effect of 50 µl purified protein mixed with 0.5% tween 20 on the leaves of weed, resulting in necrosis on target plant . Its morphological properties survey based on 18S rDNA analysis showed that this strain has the most similarity to Fusarium exosporium. These results indicated that selective destructive effect on dicotyledon weeds and non-harmful effect on the type monocotyledon plants like wheat. In addition, losing of the biological activity of phytotoxin could have any serious environmental hazard.