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-The incorporation of organic matter has been used to manage of diseases caused by soilborne pathogen, but there is a gap in the use of coffee residues on disease supressiveness. The objective of this study was to evaluate the effect of organic matter sources against cassava root rot caused by F. solani CFF109. Fertilization with coffee residue (CR), cattle manure (CM), earthworm excrements (EE) and goat manure (GM) resulted in suppression of cassava root rot. The treatments of CR and CM presented higher reduction in the cassava disease severity. There were changes in the soil microbial community structure by organic matter incorporation, mainly in total fungi and Gram-negative bacteria populations. The total organic carbon and magnesium are negatively associated with disease severity. The microbial quotient, alkaline and acid phosphatase activities were positively and the biomarker a-15:0 was negatively associated with disease severity. This study indicated that agro-industrial residues can be recycled for providing organic matter and nutrients with effect for management of plant diseases by suppressing soilborne pathogens. This is the first evidence that the industrial residue of coffee can be use in the management of cassava root rot, caused by F. solani.Keywords: Manihot esculenta. Fusarium solani. Coffee residue. Extracellular soil enzyme. Microbial community structure. FAMES E ATIVIDADES MICROBIANAS ENVOLVIDAS

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Yeasts have been used to manage a large number of plant diseases, but little is known about the mechanisms used by these biocontrol agents. The objectives of the present study were to evaluate the antagonistic effect of yeasts against Rhizoctonia solani and possible mechanisms of action in cowpea plants. Seventy yeast isolates were obtained from leaf, root and stem tissues of cowpea and common bean plants. Screening experiments were conducted in a greenhouse at temperatures ranging from 15 to 26°C in the first and from 22 to 31°C in the second experiment. Candida saopaulonensis C6A, Cryptococcus laurentii FVC10 and Bullera sinensis FVF10 (R1) reduced disease severity by 57.4%, 48.5% and 66.3%, respectively. Cowpea plants treated with FVF10 (R1) showed the highest peroxidase and catalase activities. The mechanisms of action were based on competition and induction of enzymes such as peroxidase, catalase and ascorbate peroxidase in cowpea. Candida saopaulonensis C6A, C. laurentii FVC10 and B. sinensis FVF10 (R1) are potential biocontrol agents of damping-off and stem rot caused by R. solani on cowpea plants.