Selection of fungi with biocontrol potential against the black spot disease of papaya1

Pedro Henrique Dias Dos Santos,Janieli Maganha Silva Vivas,Danilo Batista Pinho,Olinto Liparini Pereira,Silvaldo Felipe Da Silveira

doi:10.1590/1983-40632017v4749178

Pedro Henrique Dias Dos Santos, Janieli Maganha Silva Vivas + Show 3 more

Open Access

https://doi.org/10.1590/1983-40632017v4749178

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Abstract

ABSTRACT The use of fungicides is the main control measure against the black-spot disease of papaya. The biological control is an alternative to that, being the selection of mycoparasitic fungi the first step in programs aiming at this kind of control. This study aimed to obtain and select fungi with potential to the biocontrol of the black spot disease of papaya. For this purpose, 24 isolates were collected from different regions and pathosystems, and then identified morphologically and by the ITS region sequencing. In order to evaluate the mycoparasite potential, two assessments, in a randomized block design, with three replications, were carried out in a shadehouse, being the obtained isolates inoculated on papaya leaves with black spot lesions. The average time for the appearance of mycoparasitism signs and the incidence of mycoparasitized black spot lesions were evaluated. Of the 24 isolates obtained, ten were from Hansfordia pulvinata, two from Lecanicillium lecaniium, two from Simplicillium lanossoniveum, one from Sarocladium implicatum and nine from Acremonium spp. A wide variability, concerning the mycoparasitism on black spot lesions, was observed, especially for the isolates H-611, H-613, H-614 and H-615, which showed the highest colonization averages. The results demonstrate that H. pulvinata has a great potential to be used as a biocontrol agent against Asperisporium caricae.

Highlights

For the management of the black spot disease, caused by the fungus Asperisporium caricae (Speg.) Maubl., on papaya leaves in the field, one of the practices adopted to reduce the inoculum source is the elimination of the affected and senescent leaves (Suzuki et al 2007)
The study included mycoparasitic fungi obtained from leaves of okra [Abelmoschus esculentus (L.) Moench.] and scarlet eggplant (Solanum aethiopicum L. var. gilo Raddi) showing pathogens with signs of mycoparasitism similar to the black spot observed in papaya, as well as leaves of coffee (Coffea arabica L.) and frangipani (Plumeria rubra L.) showing rust mycoparasites (Table 1)
Confirming the morphological analyses, the 24 isolates were grouped into five clades (Table 1, Figure 2), which contain species previously described as having a biocontrol potential

Summary

Introduction

For the management of the black spot disease, caused by the fungus Asperisporium caricae (Speg.) Maubl., on papaya leaves in the field, one of the practices adopted to reduce the inoculum source is the elimination of the affected and senescent leaves (Suzuki et al 2007). Despite being the main form of control, the intensive use of fungicides may select resistant isolates and negatively affect the human health, environment and fruit commercialization.

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