Compatibility and combination of selected bacterial antagonists in the biocontrol of sisal bole rot disease

Abstract

Sisal (Agave sisalana Perrine ex Engelm; Asparagaceae) bole rot is a devastating disease caused by Aspergillus niger Tiegh, which contributes to the decline of this crop in Brazil. Currently, there are no control measures available, but biocontrol is being investigated as a promising management strategy. Five previously selected bacterial isolates were identified by 16S rRNA sequencing as Paenibacillus sp. 512, Brevibacterium sp. 90 and Bacillus sp. 105, BMH and INV, and tested for their capacity to control bole rot in vitro and in field experiments. Individual bacterial isolates and their combinations significantly inhibited mycelial growth and spore germination of A. niger. In two independent field experiments, the application of isolates 512, 105, 90, INV, and 127 + INV reduced disease incidence to levels varying from 44 to 75%. Although there was no synergistic effect in their combined use, these bacteria have potential to be used against bole rot disease in the field.