Commercial formulations of Bacillus spp. for sugarcane pineapple disease control and growth promotion

Fabio Brandi,Daniel Winter Heck,Wagner Bettiol,Thiago Costa Ferreira

doi:10.1590/s0100-204x2018001200003

Abstract

Abstract: The objective of this work was to evaluate the commercial formulations of Bacillus subtilis QST-713 and Bacillus pumilus QST-2808 on mycelial growth inhibition of Thielaviopsis paradoxa, for the control of the pineapple disease and growth promotion in sugarcane. The inhibition of mycelial growth was evaluated in paired culture tests. Bacillus isolates were transferred to Petri dishes 48 hours before the pathogen, and the zone of inhibition was determined. The direct effect of the autoclaved commercial formulations at 0, 0.001, 0.01, 0.1, 1.0, and 10.0% on the inhibition of pathogen mycelial growth was evaluated. Bacillus spp. potential in controlling the disease and promoting plant growth was evaluated in assays on plant development and disease severity, both under controlled conditions and in the field. Bacillus isolates inhibited pathogen mycelial growth; however, the isolates did not control the disease effectively in the growth chamber and in the field. In the field assay without infestation by the pathogen, all treatments with biocontrol agents and fungicide increased the yield of cane stalks and sugar per hectare, compared with the control. In the assay with infestation by the pathogen, the B. pumilus-based product (2.0 L ha-1) and fungicide differed from the control only for the variable number of tillers.

Highlights

Sugarcane is one of the most important agricultural crops in Brazil, and it is used for the production of food and biofuel (Aguiar et al, 2014)
In the work using the paired culture technique, to evaluate the zone of inhibition formed by the B. subtilis QST-713 and B. pumilus QST-2808 isolates, zones of inhibition of 2.16 cm and 2.21 cm, respectively, were observed for the Bacillus isolates on the fourth day
The inhibition of the pathogen mycelial growth by B. subtilis and B. pumilus based products at different concentrations showed no significant interaction between the studied factors

Summary

Introduction

Sugarcane is one of the most important agricultural crops in Brazil, and it is used for the production of food and biofuel (Aguiar et al, 2014). With the management adapted to the driest and coldest seasons (Aguiar et al, 2014), and planting in this period can be affected by Thielaviopsis paradoxa (Ceratocystis paradoxa), a fungus that causes the pineapple disease of sugarcane. This disease is associated with retards of the bud germination and shoot development, early shoot vigor, and seed piece decay (Raid & Rott, 2012; Chapola et al, 2014). These problems are aggravated by the mechanized planting, in which smaller seed pieces are used, resulting in fewer buds and more injuries (Raid & Rott, 2012; Serafim et al, 2013; Chapola et al, 2014)

Objectives

Methods

Results