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

Abstract

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.Additional keywords: Allium spp.; alternative control; white rot. ResumoStromatinia cepivora é um dos principais patógenos de espécies de Allium em todo o mundo. Partindo do pressuposto de que substâncias produzidas por plantas podem ser usadas no manejo desse patógeno, o efeito de extratos vegetais e de óleos essenciais sobre o crescimento micelial e a germinação de S. cepivora foi avaliado neste estudo. O fungo foi cultivado em BDA com extratos aquosos e etanólicos (20%, m: v) de mentrasto, arruda, gengibre, falso-açafrão, alho e citronela, nas concentrações de 1 ou 10 mL L -1 e os óleos essenciais de citronela, alecrim, nim e eucalipto citriodora, a 100; 200; 400; 800 ou 1.200 µL L -1 . Nenhum dos extratos de plantas reduziu a germinação dos escleródios. Todos os extratos aquosos a 10.000 µL L -1 reduziram o crescimento do fungo, variando de 28,0% a 53,5%. Na concentração de 10.000 µL L -1 , os extratos etanólico de gengibre, citronela, arruda e falso-açafrão reduziram o crescimento micelial do patógeno até 45,1%, especialmente o extrato de gengibre. Os óleos essenciais de todas as plantas suprimiram o crescimento micelial de S. cepivora a 800 e 1.200 µL L -1 , especialmente a citronela e os óleos de alecrim, a 1.200 µL L -1 , que causaram 100% de inibição, 5% dos escleródios germinados em BDA contendo os óleos na concentração de 1.200 µL L -1 , independentemente da planta. Os extratos de mentrasto, arruda, gengibre, açafrão e falsa-citronela e, especialmente, os óleos essenciais de citronela, alecrim, nim e eucalipto citriodora, em 1200 µL L -1 , têm...

Some Plants Showing Antagonism to Five Plant Pathogenic Fungi

“…The extract obtained from the milling and immersion in water, prepared by Garcia et al (2016) at 30% concentration, inhibited 27.71% of the growth of Ss, a result lower than that observed here (70.41%). The aqueous extract of this plant inhibited 30 and 20% of growth of Sc at concentrations of 20 and 2%, according to Fuga et al (2018), a result lower than that observed in the present study, of 70.83%. Autoclaved lyophilized extract, together with the culture medium, provided a 70.6% inhibition of Vd, according to Oliva et al (1999).…”

“…On the other hand, this plant in the 2000 (0.2%) and 2500 ppm (0.25%) concentrations inhibited 94.44% of the Fox mycelial growth (Sreenivasa et al, 2011). The aqueous extract of this plant inhibited 52% growth of Sc at a concentration of 20%, according to Fuga et al (2018), a result lower than that observed in the present study, of 100% inhibition. No citronella Ss and Vd inhibition data were accessed, although there was good fungal inhibition in the present study (72.22%).…”