Abstract: Plant pathology anthracnose by C. acutatum and C. gloeosporioides and root rot and vascular wilt by F. oxysporum and F. moniliforme caused a serious problem of crop loss in Thailand. Agricultural chemicals such as fungicides were sprayed on crops to control diseases that damaged field crops. This has created more problems because fungicide residues have been found on food for human consumption, mostly from post-harvest treatments. Piper retrofractum Vahl (long pepper) is in the Piperaceae family which can be found in Kanchanaburi, Ratchaburi and Chanthaburi Provinces of Thailand. It has been used as a Thai traditional herb ingredient in various treatment formulas. The aim of this research is to extract metabolite from long pepper using several solvents and to perform therapeutic efficacy testing against fungal of plants pathogen disease. The results showed that the bioactive metabolites extracted from P. retrofractum are effective against plant disease-causing fungi Fusarium moniliforme DOAC 1224 causes the stalk rod disease, F. oxysporum DOAC 2269 causes the yellow wilt disease, Colletotrichum gloeosporioides DOAC 2213 and C. acutatum DOAC 2285 both cause the most destructive fungal disease, anthracnose. Total of crude extracted found in isopropanol is 2.193±0.579 g/100 g of fresh pepper. Agar disc diffusion assay performed crude extracted concentrations 713 mg/mL against C. gloeosporioides is clear zone 5.25±0.35 mm. Against C. acutatum is clear zone 11.00±4.24 mm, against F. moniliforme is clear zone 9.00±4.24 mm and against F. oxysporum is clear zone at 6.50±0.71 mm. Moreover, the results can be concluded that isopropanol is an effective solvent for extracting bioactive compounds from fresh P. retrofractum. The crude metabolites have shown potential for broad range antifungal activities in plant pathogens.