2.4. Characterization and selection of fungal isolates
P. expansum and B. cinerea isolates were selected by their
aggressiveness and sensitivity to fungicides thiabendazol (TBZ) and
captan according to the following procedures.
2.4.1. Aggressiveness determination
The aggressiveness of each fungal isolate was determined by
measuring the lesions diameter (mm) induced on pear fruits after
wound inoculation with the respective fungal isolate. Pear fruits were
surface-sterilized with 70% (v/v) ethanol, and air dried prior to
wounding. One wound (3 mm deep and 3 mm wide) was made at the
equatorial region of each fruit using a conk borer. Each wound was
inoculated with 10μl of an aqueous suspension (10
6
conidia/ml) of
the respective fungal isolate. B. cinerea conidia preceded from
14-days-old cultures in light at 20 °C andP. expansumconidia from
7-days-old cultures grown in darkness at 20 °C. Treated fruits were
placed in poly-ethylene bags and incubated at 20 °C and 95% relative
humidity (RH) for seven days. Lesion diameters were measured and
recorded. Each assay was conducted three times with three fruits per
assay.
Minimal conidial concentration (MCC) was determined forB. cinerea
andP. expansumon pears. Conidia suspensions were adjusted to 10
2
to
10
6
conidia/ml. Pear fruits were disinfected, wounded and inoculated as
described above