Biological Control of Strawberry Fusarium Wilt Caused by Fusarium oxysporum f. sp. fragariae Using Bacillus velezensis BS87 and RK1 Formulation

Abstract

Two isolates, Bacillus sp. BS87 and RK1, selected from soil in strawberry fields in Korea, showed high levels of antagonism towards Fusarium oxysporum f. sp. fragariae in vitro. The isolates were identified as B. velezensis based on the homology of their gyrA sequences to reference strains. BS87 and RK1 were evaluated for control of Fusarium wilt in strawberries in pot trials and field trials conducted in Nonsan, Korea. In the pot trials, the optimum applied concentration of BS87 and RK1 for pre-plant root-dip application to control Fusarium wilt was 10 5 and 10 6 colony-forming units (CFU)/ml, respectively. Meanwhile, in the 2003 and 2005 field trials, the biological control efficacies of formulations of RK1 were similar to that of a conventional fungicide (copper hydroxide) when compared with a non-treated control. The RK1 formulation was also more effective than BS87 in suppressing Fusarium wilt under field conditions. Therefore, the results indicated that formulations of B. velezensis BS87 and RK1 may have potential to control Fusarium wilt in strawberries.

Effect of different concentrations of bacterial suspensions on biocontrol efficacy and storage stability of Bacillus cereus AR156, Pantoea ananatis YT11 and Pseudomonas fluorescens ABc9

“…Some studies showed the higher the strain concentration, the better effect of biocontrol agents got (Bonaterra et al, 2003;Patino-Vera et al, 2005). But some other reports detected there was no positive trend on the strain concentration to the biological efficacy (Wilson and Chalutz, 1989;Nam, 2009), which were similar to our study. It is possible that too much foreign biocontrol agents in the micro-ecological environment in soil creates unsuitable condition for indigenous bacteria and host plant, which might make it easier for the infection of pathogens.…”

Diffusible and Volatile Antifungal Compounds Produced by an Antagonistic Bacillus velezensis G341 against Various Phytopathogenic Fungi

“…nov. was recently isolated during a research focusing on discovering novel bacterial strains capable of synthesizing new lipopeptides with surfactant and/or antimicrobial activity ( Ruiz-Garcia et al, 2005 ). Several research groups have reported that B. velezensis have potential to control Fusarium wilt in strawberries ( Nam et al, 2009 ), wheat powdery mildew ( Cai et al, 2017 ), Fusarium head blight ( Palazzini et al, 2016 ). Recently, Gao et al (2017) reported that one endophytic B. velezensis ZSY-1 strain produces volatile compounds having antifungal activity against phytopathogenic fungi.…”

Effects of long-term continuous cropping on soil nematode community and soil condition associated with replant problem in strawberry habitat

“…Replant problem manifests in stunted growth, declined crop vigor, weak root systems, and drying foliage, all of which lead to low productivity and shortened economic life 6 7 . For continuously cropped strawberry, replant problem has been attributed to biotic and abiotic factors, including accumulated phytotoxic allelochemical substrates 8 9 10 , build-up of specific pathogenic microorganisms (fungi, bacteria and actinomycetes) 11 12 13 14 and plant-parasitic nematodes 15 16 17 , as well as unbalanced availability of plant nutrients and other declines in soil health (soil acidification, etc.).…”