Biological Management of Basal Rot of Onion by Trichoderma harzianum and Withania somnifera

R Akhtar,A Javaid

doi:10.1590/s0100-83582018360100009

Abstract

ABSTRACT: Onion is attacked by destructive soil-borne fungal plant pathogen Fusarium oxysporum f. sp. cepae, resulting in basal rot disease. In the present study, three Trichoderma species (T. pseudokoningii, T. harzianum and T. reesei) and leaves of solanaceous weed Withania somnifera were used for management of this disease. The in vitro interaction study revealed T. harzianum as the most effective biocontrol agent against the pathogen. In a pot trial, dried leaf material of W. somnifera (1%, 2% and 3% w/w) and inoculum of T. harzianum were mixed in the pot soil previously inoculated with the pathogen. The highest incidence of the disease (87%) was found in positive control (pathogen inoculation without any amendment). Different rates of dry leaf material reduced the incidence of the disease to 41-66%. T. harzianum in combination with leaf material reduced the incidence of the disease to 20-53%. In a laboratory bioassay, the dry leaf extract of W. somnifera was prepared in methanol and partitioned with n-hexane, chloroform, ethyl acetate and n-butanol. The highest concentration (200 mg mL-1) of all except for the n-butanol fraction significantly decreased fungal biomass over control. This study concludes that basal rot of onion can be controlled by combined application of W. somnifera dry leaf material and biological control agent T. harzianum.

Highlights

Onion (Allium cepa), family Alliaceae, is an economically important horticulture crop extensively cultivated worldwide (Griffiths et al, 2002)
One of the important fungal diseases of onion is basal rot disease caused by Fusarium oxysporum f. sp. cepae (Javaid and Rauf, 2015; Javaid et al, 2017a), which leads to serious crop failure and storage losses (Southwood et al, 2015)
Recent studies have shown that Trichoderma spp., especially T. harzianum, can control diseases caused by Rhizoctonia solani, Macrophomina phaseolina and Ceratocystis radicicola (Al-Naemi et al, 2016; Javaid et al, 2017b; Youssef et al, 2016)

Summary

SOCIEDADE BRASILEIRA DA CIÊNCIA DAS PLANTAS DANINHAS

BIOLOGICAL MANAGEMENT OF BASAL ROT OF ONION BY Trichoderma harzianum AND Withania somnifera. Manejo Biológico da Podridão Basal de Cebola por Trichoderma harzianum e Withania somnifera. This study concludes that basal rot of onion can be controlled by combined application of W. somnifera dry leaf material and biological control agent T. harzianum. RESUMO - A cebola é atacada por um patógeno fúngico no solo, Fusarium oxysporum, que resulta na doença da podridão basal. Três espécies de Trichoderma (T. pseudokoningii, T. harzianum e T. reesei) e as folhas da planta daninha solanácea Withania somnifera foram utilizadas para o manejo dessa doença. Este estudo conclui que a podridão basal da cebola pode ser controlada pela aplicação combinada de material de folha seca de W. somnifera e o agente de controle biológico T. harzianum. Biological management of basal rot of onion by Trichoderma harzianum and Withania somnifera

INTRODUCTION

MATERIALS AND METHODS

Laboratory bioassays

RESULTS AND DISCUSSION