Biological Control Efficiency of Fusarium Wilt of Tomato by Nonpathogenic Fusarium oxysporum Fo-B2 in Different Environments

Abstract

Efficiency of nonpathogenic Fusarium oxysporum Fo-B2 for the biological control of Fusarium wilt of tomato, caused by F. oxysporum f. sp. lycopersici CU1, was examined in different environments: a growth chamber with sterile soil-less medium, a greenhouse with fumigated or nonfumigated soil, and nonfumigated field plots. Inoculation of Fo-B2 onto tomato roots significantly reduced the severity of disease, but the efficiency of disease suppression decreased as the experimental environment became less controlled. Relationships between the recovery of Fo-B2 from hypocotyls and the disease severity indicated that the biocontrol agent was most effective when it colonized vascular tissues intensively. Moreover, the degree of Fo-B2 colonization was greatly reduced when the seedlings were grown in nonfumigated soil. Dose-response models (negative exponential, hyperbolic saturation, and logistic) were fit to observed data collected over a range of inoculum densities of the pathogen and the antagonist; the logistic model provided the best fit in all environments. The ratios of an 50% effective dose parameter for Fo-B2 to that of CU1 increased as the environment became less controlled, suggesting that environmentally related efficiency reduction impacted the antagonist more than the pathogen. The results suggest that indigenous soil microbes were a primary factor negatively influencing the efficiency of Fo-B2. Therefore, early establishment of the antagonist in a noncompetitive environment prior to outplanting could improve the efficacy of biological control.

Biocontrol efficiency of Fusarium wilt diseases by a root-colonizing fungusPenicilliumsp.

“…Root colonization by EU0013_90S increased depending on the EU0013_90S spore concentration. Shishido et al (2005) have reported differences in efficiency of nonpathogenic Fusarium oxysporum in the biocontrol of tomato wilt under different environmental conditions. They reported that a biocontrol agent was more effective when used in sterile seedbeds, compared with non-sterile soil, as it decreased competition from indigenous soil microbes.…”

“…Numerous studies using Penicillium oxalicum and non-pathogenic F. oxysporum (e.g. Duijff et al 1998;Larena et al 2003;Shishido et al 2005), have demonstrated significant reductions in the incidence and severity of tomato Fusarium wilt disease. Plant growth promoting fungi (PGPF) have also been reported to suppress plant diseases.…”

Fusarium oxysporum Protects Douglas-fir (Pseudotsuga menziesii) Seedlings from Root Disease Caused by Fusarium commune

“…Both fungi are apparently well-adapted to forest nursery environments. Previous studies using crops other than Douglas-fir in nurseries have shown that non-pathogenic F. oxysporum can prevent disease by pathogenic F. oxysporum (Fuchs et al, 1999;Fravel and Larkin, 2002;HuertasGonzalez et al, 1999;Larkin and Fravel, 2002;Shishido et al, 2005). We therefore hypothesized that some nonpathogenic isolates of F. oxysporum may have the potential to protect conifer seedlings from virulent isolates of F. commune.…”

Screening of native Trichoderma harzianum isolates for their ability to control Verticillium wilt of strawberry

“…Antagonism implies direct interaction between two microorganisms that share the same ecological niche. Such antagonists can compete with pathogens for nutrients, diminish pathogens by parasitism, inhibit growth of pathogens through antibiosis or even induce systemic resistance in plants (Shishido et al, 2005). Earlier studies demonstrated that the volatile and non-volatile compounds of a variety of fungal microorganisms inhibit the activity of pathogenic fungi.…”