Inhibition of the mycelial growth and germination of Stromatinia cepivora by plant extracts and essential oils

Resumo

Stromatinia cepivora is one of the major pathogens of Allium species worldwide. Assuming that substances pro­duced by plants may be used in the management of this pathogen, the effect of plant extracts and essential oils on the mycelial growth and germination of S. cepivora was assessed in this study. The fungus was grown on PDA medium with aqueous and ethanolic extracts (20 %, m:v) of mentrasto, rue, ginger, false saffron, garlic and citron­ella at the concentrations of 1 or 10 mL L^-1 and the essential oils of citronella, rosemary, neem and Corymbia citriodora at 100, 200, 400, 800 or 1,200 µL L^-1. None of the plant extracts reduced the germination of the sclerotia. All aqueous extracts at 10,000 µL L^-1 reduced the growth of the fungus from 28.0% to 53.5%. At the 1,000 µL L^-1, the ethanolic extracts of ginger, citronella, rue and false saffron reduced the mycelial growth of the pathogen up to 45.1 %, especially the extract of ginger. The essential oils of all the plants suppressed the mycelial growth of S. cepivora at 800 and 1,200 µL L^-1, especially the citronella and rosemary oils at 1,200 µL L^-1, which caused 100% of inhibition. 5 % of sclerotia germinated in PDA containing the oils at 1,200 µL L^-1, regardless the plants. The extracts of mentrasto, rue, ginger, false saffron and citronella and especially the essential oils of cit­ronella, rosemary, neem and C. citriodora at 1,200 µL L^-1 have substances that inhibit the growth of S. cepivora.