During the spring of 2014, the garlic fields in the province
of Hamedan, Iran were surveyed. Diseased plants showing
white rot symptoms were collected and transferred
to the laboratory so that the pathogenic agents could be
isolated. Diseased samples were processed by cutting, removing,
surface sterilising and culturing diseased pieces
of stems and bulbs on Potato Dextrose Agar (PDA) culture
medium. The grown fungal colonies were then purified
and were identified using the standard identification
keys of Barnett and Hunter (1998). Based on the abovementioned
experiments, five isolates of S. cepivorum were
identified.
The pathogenicity test (Koch postulate) was also conducted
and performed to confirm the role of the isolated
fungus in disease occurrence and symptom appearance.
The test was performed on five isolates of S. cepivorum
in a greenhouse experiment with five treatments each with
four replicates. A replicate consisted of a plastic pot containing
2 kg of garlic-field, pasteurised soil pre-inoculated
with S. cepivorum and sown with three garlic seeds (bulbs).
After the appearance of symptoms on garlic plants, the
pathogenic agent was re-isolated from the infected tissues,
identified as described in the above sections, and evaluated
for pathogenicity according to the respective disease
percent induction (Mahdizadehnaraghi et al. 2007). Based
on the above experiments, the most pathogenic isolate of
S. cepivorum was selected to be used for the rest of the study.