In this work, a bioformulation containing Trichoderma harzianum strain ITEM 3636, an effective biocontrol agent against the peanut pathogen Fusarium solani, was evaluated for control of peanut smut, an emergent disease caused by Thecaphora frezii. The performance of the bioformulation was evaluated during seasons 2014/2015 and 2015/2016 in experimental fields with history of peanut smut. Inoculation with T. harzianum ITEM 3636 significantly reduced the severity of peanut smut during both seasons by 17% and 25%, respectively. This is the first report where a consistent decrease of peanut smut symptoms is achieved in field experiments using a potential biological control agent. The identity of the causal agent of peanut smut was confirmed by sequencing the D1/D2 DNA region. T. harzianum ITEM 3636 caused significant increases in grain weight/plant in both years. Peanut smut and brown root rot are diseases that cause severe economic losses. Both causal agents may be present in the soil and, depending on environmental factors, cause disease. The T. harzianun ITEM 3636 bioformulation has high potential for controlling both diseases. Thus, the application of a single bioformulation could protect the health of peanut plants against two high impact pathogens.

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Aim: To investigate the impact of inoculating peanut seeds with the biocontrol agent Trichoderma harzianum ITEM 3636 on the structure of bacterial and fungal communities from agricultural soils. Methods and Results: Polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (PCR-DGGE) and next-generation sequencing (NGS) of amplicons (or marker gene amplification metagenomics) were performed to investigate potential changes in the structure of microbial communities from fields located in a peanut-producing area in the province of C ordoba, Argentina. Fields had history of peanut smut (caused by Thecaphora frezii) incidence. The Shannon indexes (H 0 ), which estimate diversity, obtained from the PCR-DGGE assays did not show significant differences neither for bacterial nor for fungal communities between control and inoculation treatments. On the other hand, the number of operational taxonomic units obtained after NGS was similar between all the analysed samples. Moreover, results of alpha and beta diversity showed that there were no significant variations between the relative abundances of the most representative bacterial and fungal phyla and genera, in both fields. Conclusions: Trichoderma harzianum ITEM 3636 decreases the incidence and severity of agriculturally relevant diseases without causing significant changes in the microbial communities of agricultural soils. Significance and Impact of the Study: Our investigations provide information on the structure of bacterial and fungal communities in peanut-producing fields after inoculation of seeds with a biocontrol agent. peanuts, although its production represents <2% of the world's production (Pedelini 2014). Peanut plants are susceptible to a large number of diseases that develop due to numerous factors such as the susceptibility of the cultivar to diseases, type of pathogen (fungi, bacteria or viruses), a favourable environment and biotic factors (including the microbiota associated to the plant). Such factors are part of the tetrahedron of the disease described by Brader et al. (2017). Within a favourable environment, Journal of Applied Microbiology 126, 608--623