The Occurrence of Bacterial Leaf Spot of Hydrangea Caused by Acidovorax valerianellae in Gunma Prefecture and its Pathogenicity

Abstract

A bacterial disease on leaves of potted hydrangea (Hydrangea macrophylla (Thunb.) Ser.) has occurred in Gunma Prefecture. Twenty bacterial isolates from the affected hydrangea were identified as Acidovorax valerianellae by investigating bacteriological properties and by analyzing the sequence of 16S rRNA. The isolates associated with the bacterial leaf spot of hydrangea were pathogenic to H. scandens ssp. chinensis, H. paniculata f. grandiflora (Sieb.) Ohwi and melon in addition to H. macrophylla as the original host.