Trichoderma harzianum T1A constitutively secretes proteins involved in the biological control of Guignardia citricarpa

•Trichoderma harzianum T1A is a biocontrol agent of Guignardia citricarpa.•Proteomics allowed unraveling the control mechanisms of citrus black spot.•T. harzianum T1A constitutively secretes proteins related to mycoparasitism.•T1A constitutively secretes proteins related to the induction of plant resistance.•Extracellular enzymes may be useful in the formulation of safer fungicides.