Crenate deutzia ( Deutzia crenata Sieb. & Zucc.) is a commonornamental shrub belonging to the Hydrangeaceae. In July 2007,powdery mildew infections were first noticed in a garden ofildew m wdery o P won, Korea. u S , er nt e C iversity d National Agrobiolesions on leaves and non-lignified stems were conspicuous,especially when growing in the shade (Fig. 1A). The leavesexhibited chlorotic circular patches, sometimes forming reddishdiscolorations (Fig. 1B). Production of chasmothecia was foundstarting from September and continued into November. Voucher9). 24694, F2477 KUS-F ( y t i s a Univer e at Kor are kept s n e ecim p sulation. abundant spor oped with devel s e l coloni a ici f uper s ite h WHyphal appressoria were lobed, single or opposite in pairs.Conidiophores were 55-98 × 7.5-10 µ m, composed of 3-4 cells,straight or slightly flexuous at the base, and producing conidiasingly. Conidia were ellipsoid to barrel-shaped, 25-34 × 12.5-16.5µ r a hil i r e ducing p pro and , s e bodi n i os br i conspicuous f of devoid , mgerm tubes. First formed conidia were rounded at the apex andsubtruncate at the base. Chasmothecia were 90-135 µ m in diam.,blackish brown, depressed globose. Appendages were about 8-14in number, substraight to mildly bent, 4-5 times dichotomouslybranched, apex recurved, 1-3-septate. Asci were 3-6 per chasmo-×36-45 42-52 , m u i c e th µ 18- oval, ores were p Ascos spored. 6-8- , m22×12.5-15 µ m (Fig. 1C-J). The observations were in full f o s d recor ous previ h ent wit eem agr ae i z t u e ysiphe d r E U. (Bunkina). 2005) , al. et Bolay 1997; a, ur (Nom . kam a T S. & Braun of n regio S T te I e l p the com ungus, e f h t f o ity e ident h t m confir o T3 S5 and P ers IT im d with pr e plifi m 24694 was a KUS-F om DNA fr re h T sequenced. y directl and 2009) ( al. et u ts a kam a T bed by i scr e as dresulting sequence of 560 bp was deposited in GenBankGA4 E using M d e m or f per s wa is s ogenetic analy l . Phy GU196146) (with neighbor-joining method (using Tajima-Nei model). TheKorean isolate showed 100% similarity with two sequences of E.deutaezi found on D. crenata and D. scabra Thunb. from the UK the sequence , e or f e Ther . ) respectively DQ861917 and DQ861918, (be to e pathogen h ed t i f i r e is v s analy E . deutziae .Erysiphe deutziae is the only powdery mildew fungus knownomfr Deutzia n Far a i Russ om r ed f d recor fungus has been s Thi spp. new ope with Eur om fr recently 1997) and a, ur (Nom n a p and Ja t s a E, Switzerde land and ad in Frhneance, Germa spr Polmepidt e ic , anyUK (Bolay et al., 2005; Denton and Henricot, 2007) on several species of Deutzia of record s no previou been ere has h T . ae i deutz . E of troduced species and in ve ea, where several nati Kor om r f Deaziutt hos s as it fungus as well this of ecord rst r e fi h is is t h T owing. e gr ar. a e Kor t in n a pl