First report of powdery mildew of Platanus occidentalis caused by Erysiphe platani in Korea.
In June 2012, diseased leaves of P. occidentalis exhibiting signs of powdery mildew from a park in Daegu City, Korea, were sent to the Plant Clinic of Seoul National University for diagnosis. The results indicated that nearly 99% of the approximately 1000 trees surveyed were infected with a powdery mildew. Symptoms were characterized by chlorosis, distortion, or cupping of young leaves. White superficial colonies developed amphigenously on leaves. Hyphae were flexuous to straight, branched, septate, 4-7 µm wide, and had a lobe. The structures and measurements were compatible with those of the anamorphic state of Erysiphe platani. To confirm the identification, the complete internal transcribed spacer (ITS) region of the rDNA from isolate KUS-F26959 was amplified with nested PCR and sequenced. The resulting sequence of 625 bp was deposited in GenBank (accession no. JX997805). A GenBank BLAST search of this sequence showed only one base substitution with the four sequences (JQ365940 to JQ365943) of E. platani on Platanus species. This is thought to be the first report of E. platani infection of P. occidentalis in Korea.