Evaluation of Biosurfactants Produced by Pseudomonas fluorescens for Potato Late Blight Control (Phytophthora infestans (Mont) de Bary) Under Controlled Conditions

AbstrA ct Phytophthora infestans (Mont.) de bary, causal agent of potato late blight is considered the main limiting pathogen for the production of this crop in colombia. the usual control of the disease has been performed with systemic fungicides which increase production costs, can induce pathogen resistance and have a negative impact on the environment. therefore, this study was carried out in order to find effective and environmentally friendly control alternatives for potato late blight. two Pseudomonas fluorescens native strains (039t and 021V) isolated from potato crops were evaluated against P. infestans. bacterial suspensions (obtained from minimal salts medium added with kerosene) and partially purified biosurfactants (bPP) were applied on detached leaflets for in vitro assays and on potato plants in greenhouse, for in vivo assays and the measure of inhibitory effect of the disease was assessed. the results showed the ability of P. fluorescens biosurfactants and bacterial suspensions to control the pathogen. bPP 039t was able to reduce the level of severity disease by 79.9% in vitro and 38.5% in vivo, whereas bPP 021V decreased 78.7% in vitro and 30.2% in vivo. bacterial suspensions reduced the severity level in 72.4% (039t) and 66.1% (021V) in vitro assessments and 35% in the in vivo experiment. these results show the potential of P. fluorescens biosurfactants to control the potato late blight in colombia.