Antimicrobial activity against Macrophomina phaseolina and the control of charcoal rot in soybeans using the homoeopathic drugs Sepia and Arsenicum album

Eloísa Lorenzetti,José Renato Stangarlin,Odair José Kuhn

doi:10.1590/1808-1657000562016

Eloísa Lorenzetti, José Renato Stangarlin + Show 1 more

Open Access

https://doi.org/10.1590/1808-1657000562016

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Abstract

ABSTRACT: The aim of this study was to evaluate the control of charcoal rot in soybeans using Sepia and Arsenicum album homeopathic solutions in dynamizations of 6, 12, 24, 36 and 48CH (hahnemanian centesimal scale), in addition to verify the antimicrobial activity of these treatments against Macrophomina phaseolina. Additional treatments were also used, including distilled water and a hydroalcoholic solution of 30% ethanol. In vitro tests were performed to analyze the number of micro-sclerotia and the mycelial growth of the fungus. In vivo assays were used to evaluate the progress of the disease and the size of the lesions. For the area under the mycelial growth curve (AUMGC), A. album had no effect, however, Sepia reduced up to 32% of the fungal growth. For micro-sclerotia there was no statistical difference. For the area under the disease progress curve (AUDPC), both Sepia and A. album in 24CH dynamization reduced fungal growth up to 50% and 70% in the first and second assays, respectively, compared to control treatments. These results indicate the potential of these homeopathic drugs for controlling soybean charcoal rot.

Highlights

Brazil is the second largest soybean producer in the world, after the United States, with a production of 98,981.6 thousand tons (CONAB, 2016).Over the years, with the increase of cultivated soybean area, there has been an emergence of diseases that harm productivity
The present study aimed to develop an alternative method using the homeopathic drugs Sepia and Arsenicum album against M. phaseolina, and to verify the in vitro antimicrobial activity and the control of charcoal rot in soybean plants
Arsenicum album had no effect on the area under the mycelial growth curve, Sepia inhibited the fungus, which was represented by a quadratic equation, and had a reduction of up to 32% (Fig. 1)

Summary

Introduction

With the increase of cultivated soybean area, there has been an emergence of diseases that harm productivity. One of the most important soybean diseases is charcoal rot, which is caused by the fungus Macrophomina phaseolina (Tassi) Goid (1947), which infects the roots and the lower part of the stem of the plant, causing first, discoloration, and a dark brown or black color (ALMEIDA et al, 2014). When the climate is favorable, in other words, in periods of drought and very high temperature, the disease can attack young and adult plants, and the infection usually occurs in the middle of the plant cycle (ALMEIDA et al, 2014). Pathogens that cause root rot are considered the most difficult to control and among these, REIS (2004) cites M. phaseolina. The control is based on: the practice of no tillage and the use of plants for covering the soil, in order to avoid water stress; chemical and physical soil management; strictness in the planting season; use of recommended varieties for a particular region; and the development of environments that do not let the fungus thrive (EMBRAPA, 2004), as well as alternative methods of control, such as homeopathic treatment

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