The black spot disease caused by the fungus Alternaria solani (Ellis and Martin) L. R. Jones and Gront is one of the most important diseases of tomato (Lycopersicon esculentum Mill.). The control is usually performed with fungicides, resulting in products contaminated with pesticide residues. In recent years, the use of homeopathic medicines has been highlighted in research for disease control. The aim of this study was to evaluate the in vitro fungitoxicity against A. solani by the homeopathic medicines Propolis, Isotherapic of A. solani and Isotherapic of ash, at 6, 12, 30 and 60CH (hahnemanian centesimal) dynamizations, and Sulphur, Silicea terra, Staphysagria, Phosphorus, Ferrum sulphuricum and Kali iodatum at 6, 12, 30 and 100CH dynamizations. Distilled water and 30% hydroalcoholic solution were used as controls at 12, 30, 60 and 100CH dynamizations. Mycelial growth, sporulation and conidial germination of A. solani were evaluated. The results indicated that for mycelial growth only in Sulphur and Staphysagria 100CH showed suppressive effect compared to both controls. For sporulation, Propolis 6, 30 and 60CH and Ferrum sulphuricum 6 and 30CH caused inhibition and differed from both controls. Isotherapic of A. solani 6CH, Isotherapic of ash 6CH and Ferrum sulphuricum 30CH reduced spores germination of the pathogen. It was also found that distilled water at 60 and 100CH inhibited mycelium growth. These results indicate the potential of some homeopathic medicines for trials aiming to control the black spot disease in tomato crops.
Key words: Homeopathy, alternative control, black spot, Solanum lycopersicum.