First Confirmed Report on Powdery Mildew of Phlox paniculata Caused by Golovinomyces magnicellulatus in Korea

Abstract

century. Various horticultural varieties areildew m y ea. Powder Kor in al purposes t n e r ornam o planted f widelyer h 1B) are rat ig. F ( orescence and infl 1A) ig. (F on leaves ons infecticommon and troublesome in gardening of this plant in Korea.ined m not been deter ungus has f l of the causa y the identit , However. e at t phic s or lack of teleom to due - o m abundant chas h wit ildew lesions m y 9, powder t 200 gus u A n Ithecia were found on P. paniculata for the first time in Andong,Korea (Fig. 1C). Further surveys in several localities in Koreaincluding Yeongwol, Jeongseon and Yanggu showed that thispowdery mildew fungus is commonly found in these places withmature chasmothecia. The phenomenon was rather surprising,becaus onle conidialye of powderyt a t s mldew has been foui nd onthis plant (Kwon and Park, 2003; Shin, unpublished data). Thevoucher specimens are kept at Korea University (KUS-F24480,F24739). The conidiophores were 70-240 m long and producing 2-6immature conidia in chains with sinuate edge-line. Conidia wereellipsoid or doliiform, 25-35 × 12.5-17.5 m, and without distinct150 100- , l ca own, spheri thecia were dark br o m osin bodies. Chas fibrwere ages d n e App 1D). (Fig. asci l a ained sever t and con . m a di n i mmycelioid, 12-28 per chasmothecium0.5- , 2.5 timesa slong as t hechasmothecial diam., 1-5-septate. Asci were shortly stalked, 55-75 × 5-372 m. Ascospores wer2-spor and d e ellipsoid-ovoid and eod in go are istics character phological r o ese m h T . 22 m 15- × 32 22-agreement with those of previous records of Golovinomycesmagnicellulatus ). 1997 nda, a 987; T 1 (Braun, S rDNA of the The T comI lete p two isolates washwitied amplifprimers ITS5 and P3 and directly sequenced. The sequencesobtained were identical to each other and deposited in GenBank(accession nos. GU945756, GU945757). Phylogenetic analysisng i s u od ( th e ng m oini j - ghbor th nei MEGA4 wi ing us out ried was carn lable i quences avai e s the h ison wit ar p Com ances). t s ei di N - a m i j a Te 100% quences shar e s S T e I h at t h vealed t e GenBank database r e thof ence u q th a se 2 bp) wi (512/51 rity a l i sim latus u magnicell . G on P.paniculata t a th th ) wi p 10/512 b (5 d 99% n a pan a J om r f (AB077621) of ulatus l l ce magni . G host e the sam on e USA. h t om r f 1303) F01 A (Therefore, the sequence analysis confirmed the identity of theogen as path . tus a magnicellul . GPowderyildew on m ta a panicul . P by d cause tus a magnicellul . Gun, a r B ope ( Eur tended to x e ica and er h Am t Nor om fr ecorded was rldew i m y Powder 97). da, 19 n a T d in Japan ( foun recently 7) and 198as d e record t s ant in Korea was fir pl is h on t Oidium Kwon and by sp.ungus is that the f t gures sugges i tion and f r descrip i e Th 2003). ( k r a Pan anamorphic state of G. magnicellulatus . Therefore the present t of unded repor -fo rst well i is the f k wor tus a magnicellul . G on Phloxin Korea although this pathogen is likely to have been present for. w no e befor s ear y