Aesculus hippocastanum L. (horse chestnut) and Aesculus xcarnea Hayne (red horse-chestnut) are ornamental tree species commonly planted in parks, gardens and boulevards. In October 2012, typical symptoms of powdery mildew were observed on leaves of several A. xcarnea trees in the University campus of Grugliasco (Piedmont, northern Italy). Trees were 12 years old, about 6 m tall and 20 cm diameter. Whitish fungal mycelium and abundant cleistothecia were visible macroscopically on the both the upper and lower leaf surfaces. Cleistothecia were yellow or light brown and dark brown or black upon maturity. They were globose, 98.4 to 123 um in diameter (on average 105.6 um), with hooked and undulate appendages 108.2-147.6 um long (on average 123 um); short, bristle-like appendages were also observed. Several asci per cleistothecium were present; ascospores were hyaline, ellipsoid and single-celled (17-28 x 9-13 um). Based on these micro-morphological characters, the fungus was identified as Erysiphe flexuosa (Peck) U. Braun & S. Takam. (syn. Uncinula flexuosa), a powdery mildew introduced from North America and now reported from Aesculus spp. in several European countries (Tozlu and Demirci, 2010). Reports from Italy were limited to A. hippocastanum (Parrini and Braccini, 2003). Therefore, to our knowledge this is the first report of E. flexuosa on A. xcarnea in Italy.
First report of the powdery mildew Erysiphe flexuosa on Aesculus xcarnea in Italy
GIORDANO, LUANA;BOCCA F.;GONTHIER, Paolo
2013-01-01
Abstract
Aesculus hippocastanum L. (horse chestnut) and Aesculus xcarnea Hayne (red horse-chestnut) are ornamental tree species commonly planted in parks, gardens and boulevards. In October 2012, typical symptoms of powdery mildew were observed on leaves of several A. xcarnea trees in the University campus of Grugliasco (Piedmont, northern Italy). Trees were 12 years old, about 6 m tall and 20 cm diameter. Whitish fungal mycelium and abundant cleistothecia were visible macroscopically on the both the upper and lower leaf surfaces. Cleistothecia were yellow or light brown and dark brown or black upon maturity. They were globose, 98.4 to 123 um in diameter (on average 105.6 um), with hooked and undulate appendages 108.2-147.6 um long (on average 123 um); short, bristle-like appendages were also observed. Several asci per cleistothecium were present; ascospores were hyaline, ellipsoid and single-celled (17-28 x 9-13 um). Based on these micro-morphological characters, the fungus was identified as Erysiphe flexuosa (Peck) U. Braun & S. Takam. (syn. Uncinula flexuosa), a powdery mildew introduced from North America and now reported from Aesculus spp. in several European countries (Tozlu and Demirci, 2010). Reports from Italy were limited to A. hippocastanum (Parrini and Braccini, 2003). Therefore, to our knowledge this is the first report of E. flexuosa on A. xcarnea in Italy.
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
