Open Access

ARTICLE

Control of seedling damping off caused by Rhizoctonia solani and Sclerotium rolfsii using onion broths

by Rivera MC, ER Wright, MC Fabrizio, G Freixá, R Cabalini, SE Lopez

1 Cátedra de Fitopatología, Facultad de Agronomía, Universidad de Buenos Aires.
2 Departamento de Métodos Cuantitativos y Sistemas de Información, Facultad de Agronomía, Universidad de Buenos Aires.
3 Departamento de Biodiversidad y Biología Experimental. Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria (1428), Buenos Aires, Argentina.

* Corresponding Author:Address Correspondence to: Marta C. Rivera, Av. San Martín 4453, Ciudad Autónoma de Buenos Aires, CP1417DSQ, e-mail:

Phyton-International Journal of Experimental Botany 2013, 82(all), 227-234. https://doi.org/10.32604/phyton.2013.82.227

Abstract

Damping off is a frequent disease that kills seedlings. Cultural and biological controls are the only tools in organic crops to manage this disease, and only empirical information is available on the efficiency of plant preparations. This work evaluates the effects of fermented onion decoctions on the growth of Rhizoctonia solani and Sclerotium rolfsii and disease incidence. Broth (B) and sterilized broth (SB) were respectively obtained by boiling chopped yellow onions in water, and incubating for 14 days at room temperature, with or without subsequent sterilization. The pathogens were grown on potato dextrose agar supplemented with B and SB, diluted at 1.7, 3.3, 8.3, 16.7 and 25% (v/v). Their growth was reduced by B at 8.3, 16.7 and 25%. Production of sclerotia by S. rolfsii was diminished by B, but stimulated by SB. Penicillium purpurogenum, P. simplicissimum and Aspergillus niger obtained from B behaved as antagonistic against both pathogens, showing antibiosis, competition and hyperparasitism in dual confrontations with them. Broth and SB at 10 and 50% dilutions were sprayed on chard (Beta vulgaris), tomato (Solanum lycopersicum), pepper (Capsicum annuum) and eggplant (Solanum melongena) seedlings cultivated in pathogen-colonized soil. Damping off incidence in the B treatment at 50% dilution was markedly lower than that in SB. It is concluded that B antifungal activity depends on its dilution and mycota. Broth sprays should be considered as a tool to control damping off in low-environment-impact crop production. Further studies are needed for a complete understanding of B chemical and microbiological components, as well as their changes during fermentation.

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