Rice blast is a dangerous disease that causes major damage to rice productivity worldwide. The purpose of this report is to examine the protease activity of Pyricularia grisea and the effects of Commelina communis L. (common name “day flower”) extract on mycelial growth. The result showed that three isolates were collected from wild rice (Oryza rufipogon) based on a designation of new international standard and namely as U43-i4-k024-z05-ta532 (isolate 1); U12-i0-k101-z05-ta102 (isolate 2) and U43-i4-k141-z15-ta522 (isolate 3). Particularly, the third isolate showed the highest protease enzyme activity of 30.11 U/ml, followed by isolate 1 (20.27 U/ml) and isolate 2 (12.81 U/ml). The new fungi isolated from wild rice may be important methods to control detrimental diseases infesting cultivated rice. The result showed methanol extract from the day flower inhibitions on P.grisea. Besides protease activity, fungi inhibition was also affected. The protease activity was low; the mycelial growth inhibition was high (IC50 = 2.35mg/mL at Isolate 2). Plant extracts from the day flower saved money and were environmentally friendly. So the implementation of this substance is very essential.