qRT-PCR quantification of the biological control agent Trichoderma harzianum in peat and compost-based growing media

►Similar pattern in T. harzianum quantification are achieved with qPCR and plate counting. ►qRT-PCR can be used to quantify active populations of BCAs in organic substrates. ►The active population of T. harzianum continually increased during melon plant cultivation in both organic substrates. ►Plants grew in green compost show a lower pathogen incidence and a lower fresh weigh loss than in peat. ►Green compost amended with T. harzianum can be a good substitute of peat in greenhouse nursery.