Common bean (<i>Phaseolus vulgaris</i> L.) is one of the most important crops in human food production. The occurrence of diseases, such as white mold, caused by <i>Sclerotinia sclerotiorum</i> can limit the production of this legume. The use of <i>Trichoderma</i> has become an important strategy in the suppression of this disease. The aim of the present study was to evaluate the effect of volatile organic compounds (VOCs) emitted by <i>Trichoderma azevedoi</i> CEN1241 in five different growth periods on the severity of white mold in common bean. The <i>in vitro</i> assays were carried out in double-plate and split-plate, and the <i>in vivo</i> assays, through the exposure of the mycelia of <i>S. sclerotiorum</i> to the VOCs of <i>T. azevedoi</i> CEN1241 and subsequent inoculation in bean plants. Chemical analysis by gas chromatography coupled to mass spectrometry detected 37 VOCs produced by <i>T. azevedoi</i> CEN1241, covering six major chemical classes. The profile of VOCs produced by <i>T. azevedoi</i> CEN1241 varied according to colony age and was shown to be related to the ability of the biocontrol agent to suppress <i>S. sclerotiorum</i>. <i>T. azevedoi</i> CEN1241 VOCs reduced the size of <i>S. sclerotiorum</i> lesions on bean fragments <i>in vitro</i> and reduced disease severity in a greenhouse. This study demonstrated in a more applied way that the mechanism of antibiosis through the production of volatile compounds exerted by <i>Trichoderma</i> can complement other mechanisms, such as parasitism and competition, thus contributing to a better efficiency in the control of white mold in bean plants.

Several Trichoderma species are known to be able to establish beneficial interactions with plants. These interactions are complex and involve different mechanisms and modes of action that can act individually or together. The production of secondary metabolites, including volatile organic compounds (VOCs) is involved in these interactions and these compounds have been detected and characterized. Methodologies to evaluate the role of VOCs from Trichoderma in the biological control and in the plant growth promotion are some of the difficulties to study the subject. This review summarizes advances in knowledge of VOCs from Trichoderma and the methodologies/adaptations to evaluate the effects of VOCs in the selection of strains for biological control. The action of these VOCs is mainly mentioned for Sclerotinia sclerotiorum. This review also shows the possible classes and VOCs, which have the capacity to promote plant growth.

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