This research aims to determine the effectiveness of soursop leaf extract, kaffir lime leaf extract, piper betle leaf extract and a combination of the three as a botanical fungicide to control maize downy mildew. Maize plants in this study were planted in soil media in polybags using a Complete Randomized Design 1 factor with 9 levels of treatment : H0 (no fungicide), H1 (soursop leaf extract 100g/l distilled water), H2 (kaffir lime leaf extract 100g/l distilled water), H3 (piper betle leaf extract 100g/l distilled water), H4 extract of (soursop leaf 50g+kaffir lime leaf 50g)/l distilled water), H5 extract of (soursop leaf 50g+piper betle leaf 50g)/l distilled water), H6 extract of (kaffir lime leaf 50g+piper betle leaf 50g)/l distilled water), H7 extract of (soursop leaf 33.3g+kaffir lime leaf 33.3g+piper betle leaf 33.3g)/l distilled water) and H8 (inorganic fungicide Cupric Oxide). The results of the research showed that the extract application of soursop, kaffir lime, piper betle and a mixture of the three resulted in the intensity of maize downy mildew ranging from 18.50%-22.91%, equivalent to the application of cupric oxide of 20.25%, while without fungicide treatment the intensity of downy mildew was 48.16%. Therefore, these three botanical materials have the potential to be used as botanical fungicides to control downy mildew disease in maize plants. The three botanical extracts support better growth and yields of maize plants. A mixture of (soursop leaf 33.3g+kaffir lime leaf 33.3g+piper betle leaf 33.3g)/l distilled water (H7) gave the heaviest seed weight 195.55g/plant.