The effect of red leaf (

Sclerotium rolfsii Sacc. is a pathogenic fungus that attacks soybeans and peanuts, causing damping off diseases. This diseases occurs when before the seeds germinate (pre-emergence damping off). and. when germinating seeds die due to biotic stress (post-emergence damping off). Common control methods involve the use of chemical pesticides, which can have negative impacts. A safe way to control S. rolfsii is to use botanical pesticides, namely red leaf (Syzygium oleana L.). because this plant contains flavonoids, terpenoids, triterpenoids, steroids, alkaloids, and coumarins, which can act as antifungals are environmentally friendly. This study aims to determine the effect of S. oleana aquoeus extract on the incidence of damping off diseases in soybeans and peanuts caused by S. rolfsii. This study was conducted at the Research Laboratory of the Department of Biology, Padang State University, using a Completely Randomised Design with 5 treatments and 4 replicates. The treatments used were S. oleana aquoeus extract with concentrations of 70%, 80%, 90%, 100%, and 0% (control). The percentage of damping off was statistically analysed using ANOVA and Duncan's Multiple Range Test (DNMRT) at a significance level of 5%. The effectiveness of control was analysed descriptively. The results showed that S. oleana aquoeus extract affected the incidence of damping off diseases in soybeans and peanuts caused by S. rolfsii. All treatments different significantly from the control. The disease control efficacy of S.oleana aquoeus extract with a 100% treatment was moderately capable in soybeans and very capable in peanuts.