First Report of Gray Mold on Crepe Myrtle (Lagerstroemia indica ) Caused by Botrytis cinerea in Korea

RNA polymerase subunit II (RPB2) that are commonly used for Botrytis species
identifications (Staats et al. 2005), were also sequenced for isolate BR003. The G3PDH,
HSP60, and RPB2 sequences <strong>of</strong> BR003 (KT728902, KT728903, and KT728904) had 99, 100
and 99% identity with the published GenBank accessions KM016535, KM016534 and
KM032181 respectively. For pathogenicity testing, three detached inflorescences were
sprayed with a conidial suspension (2 × 10 4 conidia/ml) prepared from a PDA culture and
were maintained with petioles immersed in sterilized water. An analogous three
inflorescences, serving as controls, were sprayed with sterilized water. All inflorescences were
sealed in plastic bags and incubated in humid chambers at 20 ± 2°C. After 5 days flower
petals <strong>of</strong> the inoculated treatments had brownish blemishes and blackish gray mycelia with
conidia, whereas control inflorescences remained symptomless. The pathogenicity test was
repeated with similar results. The pathogen was successfully re-isolated from inoculated
flowers, fulfilling Koch’s postulates. <strong>Gray</strong> mold disease <strong>of</strong> L. indica caused by B. cinerea has
been recorded in China and New Zealand (Farr and Rossman 2015). To our knowledge, this is
the first report <strong>of</strong> gray mold on L. indica in Korea. According to our field observations, gray
mold was active at low temperatures and lesions expanded rapidly in humid conditions.
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