Inoculation and co-inoculation of two monosporic fungi onto surface-sterile blackberry fruits for quantification experiments

Trichoderma is used as a biocontrol agent against different plant pathogens in different crops. In Costa Rica, Trichoderma isolates from blackberry fruits (Rubus adenotrichos Schltdl.) have shown antagonism in laboratory and field trials against Botrytis cinerea. Quantifying fungal antagonistic activity directly on target organs or target tissues is of interest to estimate the performance of biocontrol agents. However, this is difficult due to the lack of visual manifestations of fungal structures. As part of a larger study to quantify antagonistic activity by quantitative PCR, we detail here a method to isolate and purify each fungus and then inoculate or co-inoculate them onto surface-sterilized blackberry fruits. • A procedure to co-inoculate the surfaces of blackberry fruits with monosporic fungal suspensions for molecular analyses is described. • The protocol described herein was implemented for subsequent qPCR analysis.