A potential of five rhizosphere biocontrol agents (BCAs), Acremonium zonatum, Aspergillus niger , Chaetomium globosum , Penicillium herquei and Trichoderma viride were studied under in vitro and in vivo experiments for controlling damping-off and wilt pathogens (Fusarium moniliforme, F. oxysporum, F. solani and Rhizoctonia solani) of adzuki bean (Phaseolus angularis L.) and snap bean (Phaseolus vulgaris L.). Aqueous neem leaf extract 40% and benlate (fungicide) were tested for comparison. In vitro experiment showed that all the bioagents as well as neem extract and benlate inhibited the growth of the damping-off and wilt pathogens with various ratios. T. viride causes the highest growth inhibition values while P. herquei gave the lowest ones. In vivo experiments showed that all the BCAs reduced the disease incidence with damping-off and wilt of both bean varieties. T. viride was the most efficient BCA against all pathogens, while neem extract and benlate were less effective. Application of T. viride culture or culture filtrate by soil infestation or seed dressing significantly reduced disease incidence and in some cases completely eradicated the disease especially when seeds soaked for 20 or 30 min in T. viride filtrate. Neem extract and benlate were less significant. Results showed that T. viride was more virulent in controlling Fusarium spp. and Rhizoctonia solani the causal agents of damping-off and wilt of bean plants in comparison with neem extract and benlate.
Key words: Bean, Fusarium spp., Rhizoctonia solani, bioagents, neem extract, benlate
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