Biological control of sclerotinia stem rot of canola using antagonistic bacteria

Abstract

Stem rot caused by Sclerotinia sclerotiorum is a major fungal disease of canola worldwide. In Australia the management of stem rot relies primarily on strategic application of synthetic fungicides. In an attempt to find alternative strategies for the management of the disease, 514 naturally occurring bacterial isolates were screened for antagonism to S. sclerotiorum. Antifungal activity against mycelial growth of the fungus was exhibited by three isolates of bacteria. The bacteria were identified as Bacillus cereus (SC-1 and P-1) and Bacillus subtilis (W-67) via 16S rRNA sequencing. In vitro antagonism assays using these isolates resulted in significant inhibition of mycelial elongation and complete inhibition of sclerotial germination by both non-volatile and volatile metabolites. The antagonistic strains caused a significant reduction in the viability of sclerotia when tested in a greenhouse pot trial with soil collected from the field. Spray treatments of bacterial strains reduced disease incidence and yielded higher control efficacy both on inoculated cotyledons and stems. Application of SC-1 and W-67 in the field at 10% flowering stage (growth stage 4Á00) of canola demonstrated that control efficacy of SC-1 was significantly higher in all three trials (over 2 years) when sprayed twice at 7-day intervals. The greatest control of disease was observed with the fungicide Prosaro â 420SC or with two applications of SC-1. The results demonstrated that, in the light of environmental concerns and increasing cost of fungicides, B. cereus SC-1 may have potential as a biological control agent of sclerotinia stem rot of canola in Australia.

Bacillus pumilus strain YSPMK11 as plant growth promoter and bicontrol agent against Sclerotinia sclerotiorum

“…Over last few decades interest in biocontrol against SSR increased, because downfall of chemical pesticides controls the pathogen as well as their impact on environment (Saharan and Mehta 2008). Although several biocontrol agents have been reported to control SSR in different crops (Awais et al 2008;Hu et al 2013;Kamal et al 2015), least information is available on biocontrol of SSR in cauliflower. In an earlier study, B. pumilus SQR-N43 exhibited 68% control efficacy against R. solani in cucumber (Huang et al 2012).…”

Biological control of the soil-borne fungal pathogen Sclerotinia sclerotiorum –– a review

“…The mean disease incidence in the treatment with B. subtilis BY-2 was 8.9-11.8%, while it was 18.1-22.9% in the control. Kamal et al (2015) showed that two applications of B. cereus SC-1 at 7-day intervals significantly reduced the incidence of sclerotinia stem rot of canola (6.5-9.3%), compared with the control (20.0-29.8%).…”

“…In most cases Pseudomonas showed multiple mechanisms in the biocontrol of diseases caused by S. sclerotiorum. Zazzerini 1987;Zhang and Fernando 2004a;Chitrampalam et al 2008;Hu et al 2011;Zeng et al 2012a, b;Monteiro et al 2013;Hu et al 2014;Kamal et al 2015 Bacillus megaterium Hu et al 2013;Hu et al 2014 Bacillus amyloliquefaciens Fernando et al 2007 Bacillus cereus Zazzerini 1987;Kamal et al 2015 Erwinia herbicola (Pantoea agglomerans) Godoy et al 1990b;Yuen et al 1994 Pseudomonas chlororaphis Zhang and Fernando 2004b;Savchuk and Fernando 2004;Fernando et al 2007;Selin et al 2010 Pseudomonas fluorescens Bin et al 1991;Expert and Digat 1995 Pseudomonas putida Expert and Digat 1995…”

Effects of rhizobacteria on the respiration and growth of Cerasus sachalinensis Kom. seedlings

“…Various microbial species are present in the soil, but only few of them have certain advantages and significantly impact on plant growth (Kamal et al, 2015). Studies on the biological control of deleterious rhizosphere microorganisms, identification of plant growthpromoting rhizobacteria (PGPR) and beneficial and harmful effects of microorganisms on plants have received considerable attention in recent years (Dutta et al, 2008;Zhou et al, 2015).…”

“…The bacteria significantly affect the plants when they are sufficient in number. Similarly to biological agents, bacterial inoculations need to reach an optimal amount to show an obvious effect (Yu et al, 2012;Qin et al, 2014;Kamal et al, regulate the EMP pathway. The key enzymatic activities in EMP were unchanged by the growth-promoting Str.…”