In vitro antimicrobial activity and alternative control of anthracnose in papaya

Héber Ferreira Dos Reis,Silvana De Paula Quintão Scalon,Lilian Maria Arruda Bacchi,Jasna Karoliny Pereira Flores

doi:10.1590/1808-1657000192018

Héber Ferreira Dos Reis, Silvana De Paula Quintão Scalon + Show 2 more

Open Access

https://doi.org/10.1590/1808-1657000192018

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Abstract

ABSTRACT: We evaluated the efficacy of natural products in the control of papaya anthracnose, in vitro and in vivo. The in vitro experiments for evaluation of mycelial growth used a completely randomized 10 × 4 factorial design (treatments × evaluation periods) with eight replicates, with sporulation evaluated at the end of the experiment. The treatments involved the use of aqueous extract at concentrations of 5 and 15% for Syzygium aromaticum (L.) Merr. & Perry (clove), Cinnamomum zeylanicum Breym (cinnamon), and Zingiber officinalis Rox. (ginger); 1 and 3% chitosan; the fungicide Prochloraz at 100 µg.mL-1; and a control (no treatment). For evaluating conidia germination, we used six treatments with five replicates. The treatments included 7.5% of each extract (clove, cinnamon, and ginger), 1.5% chitosan, and 50 µg.mL-1 of Prochloraz. For the in vivo experiment, “Formosa” papaya “Tainung 1” was used in a completely randomized design, with six treatments and four replicates to evaluate the severity of anthracnose caused by Colletotrichum gloeosporioides. The fruits were treated by immersion for 5 min with 15% clove, cinnamon, and ginger extracts, 8% chitosan, and control with distilled water, and immersion for 2 min in Prochloraz (33.75 g a.i./100 L). The treatments with 15% clove extract and 8% chitosan were effective in all evaluations, resulting in a viable alternative to the fungicide Prochloraz. The treatments with ginger extract were less effective and those with cinnamon offered intermediate control.

Highlights

MATERIAL AND METHODSAnthracnose of papaya, caused by Colletotrichum gloeosporioides Penz., is very important economically — the fruits affected by this disease become unsuitable for commercialization and consumption
Mycelial growth was completely inhibited by treatments with 5 and 15% clove, 1 and 3% chitosan, and the fungicide Prochloraz, which differed from the other treatments (Fig. 1)
Inhibition of mycelial growth by ginger extract was confirmed by BRITO; NASCIMENTO (2015): they found that the 5% concentration of ginger extract provided 70% inhibition of mycelial growth of Curvularia eragrostidis

Summary

Introduction

Anthracnose of papaya, caused by Colletotrichum gloeosporioides Penz., is very important economically — the fruits affected by this disease become unsuitable for commercialization and consumption. The fruits do not show symptoms of the disease at harvest, it manifests itself during the packaging, transportation, ripening, and commercialization phases, causing substantial losses (SIQUEIRA JUNIOR et al, 2011). Post-harvest disease control in papaya is usually done by immersing the fruits in water at 48–49oC for 20 min, followed by another immersion at 14oC for 20 min. The application of waxes and fungicides is recommended to guarantee longer fruit survival (CARNELOSSI et al, 2009). The use of fungicides is an important control strategy, their residues in fruits have generated cause for concern owing to their negative effects on human health and the environment. In 2016, ANVISA prohibited the use of the active ingredient Prochloraz in pesticides, based on the results of its toxicological reassessment per the newly adopted guidelines and toxicological evaluation requirements (ANVISA, 2016)

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