The sensitivity of P. noxius to PCA was assessed in PDA plates. Mycelial discs (5 mm) were removed from one-week-old PDA plates and placed in the center of a 90-mm-diameter petri plate containing PDA plates supplemented with six different concentrations of PCA (1.25, 2.5, 5, 10, 20, and 40 μg/mL), these plates without PCA as control. Each treatment was performed in triplicate. The petri plates were incubated at 30 °C for 9 days, and radial growth was measured at the end of the trial. Growth inhibition of P. noxius by PCA was quantified as described previously [9 (link)].
For PDB medium, 150 mL conical flasks containing 40 mL of potato dextrose broth (PDB) supplemented with five different concentrations of PCA (1.25, 2.5, 5, 10, and 20 μg/mL) were inoculated with mycelial discs (5 mm), excised from one-week-old PDA plates with chloroform/methanol (0.1%, v/v) as control. Each treatment was performed in triplicate. Flasks were incubated on a rotary shaker (220 rpm) at 30 °C for 6 days. After 72 h, mycelia were examined under optical microscopy (Nikon DS-Ril-U2, Tokyo, Japan). At the end of the incubation period, mycelia were collected from each flask, dried at 80 °C, and then weighed.
For PDB medium, 150 mL conical flasks containing 40 mL of potato dextrose broth (PDB) supplemented with five different concentrations of PCA (1.25, 2.5, 5, 10, and 20 μg/mL) were inoculated with mycelial discs (5 mm), excised from one-week-old PDA plates with chloroform/methanol (0.1%, v/v) as control. Each treatment was performed in triplicate. Flasks were incubated on a rotary shaker (220 rpm) at 30 °C for 6 days. After 72 h, mycelia were examined under optical microscopy (Nikon DS-Ril-U2, Tokyo, Japan). At the end of the incubation period, mycelia were collected from each flask, dried at 80 °C, and then weighed.