scholarly journals First Report of Powdery Mildew (Oidium sp.) on Akebia quinata in Italy

Plant Disease ◽  
2004 ◽  
Vol 88 (6) ◽  
pp. 682-682
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
M. L. Gullino
Keyword(s):  
Powdery Mildew ◽  
The Netherlands ◽  
Northern Italy ◽  
Abaxial Surface ◽  
First Report ◽  
The Family ◽  
White Mycelium ◽  
The University ◽  
Ornamental Species

Akebia quinata Decne., an ornamental species belonging to the family Lardizabalaceae, is used as a climbing species in gardens to cover walls as well as supports and is very much appreciated because of its dark red flowers. During the summer of 2003, severe outbreaks of a previously unknown powdery mildew were observed on established plantings in several gardens near Biella (northern Italy). The upper surfaces of leaves were covered with white mycelium, and the corresponding abaxial surface of infected leaves were chlorotic. Young, green stems also affected showed extended chlorosis. As the disease progressed, infected leaves turned yellow and died. Foot cell was cylindric and appressorium lobed. Conidia formed singly were hyaline, ellipsoid, and measured 26.4 to 45.6 × 10.6 to 15.6 μm (average 35.1 × 12.7 μm). Fibrosin bodies were not present. The pathogen was identified as Oidium sp. subgenus Pseudoidium (1) partially because cleistothecia were not observed. Conidial measurements are close to those reported for Microsphaera akebiae Sawada. Pathogenicity was confirmed by gently pressing diseased leaves onto leaves of healthy A. quinata plants. Three plants of A. quinata were used as replicates. Noninoculated plants served as controls. Plants were maintained between 20 and 30°C in a garden located 5 km from where the disease was originally found. After 10 days, typical symptoms of powdery mildew developed on inoculated plants. Noninoculated plants did not show symptoms. To our knowledge, this is the first report of the presence of powdery mildew on A. quinata in Italy. The disease is currently restricted to the area of Biella. The presence of M. akebiae was recently reported in the Netherlands (2). Specimens of this disease are available at the DIVAPRA Collection at the University of Torino. References: (1) U. Braun and S. Takamatsu. Schlechtendalia, 4:1, 2000. (2) M. Scholler and W. Gams. Nova Hedwigia, 67:101, 1998.

scholarly journals First Report of Powdery Mildew Caused by Erysiphe aquilegiae var. aquilegiae on Aquilegia flabellata in Italy

Plant Disease ◽  
2004 ◽  
Vol 88 (6) ◽  
pp. 681-681
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
M. L. Gullino
Keyword(s):  
United States ◽  
Powdery Mildew ◽  
The United States ◽  
Northern Italy ◽  
American Phytopathological Society ◽  
First Report ◽  
Powdery Mildews ◽  
The Family ◽  
White Mycelium ◽  
The University

Aquilegia flabellata Sieb. and Zucc. (columbine) is a perennial garden species belonging to the family Ranunculaceae. During the summer of 2003, a severe outbreak of a previously unknown powdery mildew was observed in several gardens near Biella (northern Italy). Upper surfaces of leaves were covered with a white mycelium and conidia, and as the disease progressed infected leaves turned yellow and died. Foot cell was cylindric and appressorium lobed. Conidia were hyaline, ellipsoid, and measured 31.2 to 47.5 × 14.4 to 33 μm (average 38.6 × 21.6 μm). Fibrosin bodies were not present. Cleistothecia were globose, brown, had simple appendages, ranged from 82 to 127 (average 105) μm in diameter, and contained one to two asci. Ascocarp appendages measured five to eight times the ascocarp diameter. Asci were cylindrical (ovoidal) and measured 45.3 to 58.2 × 30.4 to 40.2 μm. Ascospores (three to four per ascus) were ellipsoid or cylindrical and measured 28.3 to 31.0 × 14.0 to 15.0 μ;m. On the basis of its morphology, the pathogen was identified as Erysiphe aquilegiae var. aquilegiae (1). Pathogenicity was confirmed by gently pressing diseased leaves onto leaves of five, healthy A. flabellata plants. Five noninoculated plants served as controls. Inoculated and noninoculated plants were maintained in a garden where temperatures ranged between 20 and 30°C. After 10 days, typical powdery mildew symptoms developed on inoculated plants. Noninoculated plants did not show symptoms. To our knowledge, this is the first report of the presence of powdery mildew on Aquilegia flabellata in Italy. E. communis (Wallr.) Link and E. polygoni DC. were reported on several species of Aquilegia in the United States (2), while E. aquilegiae var. aquilegiae was previously observed on A. flabellata in Japan and the former Union of Soviet Socialist Republics (3). Specimens of this disease are available at the DIVAPRA Collection at the University of Torino. References: (1) U. Braun. Nova Hedwigia, 89:700, 1987. (2) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St Paul, MN, 1989. (3) K. Hirata. Host Range and Geographical Distribution of the Powdery Mildews. Faculty of Agriculture, Niigata University, 1966.

scholarly journals First Report of Powdery Mildew Caused by Oidium Subgenus Pseudoidium on Lonicera caprifolium in Italy

Plant Disease ◽  
2004 ◽  
Vol 88 (9) ◽  
pp. 1045-1045
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
M. L. Gullino
Keyword(s):  
Powdery Mildew ◽  
Growing Season ◽  
Northern Italy ◽  
First Report ◽  
Leaf Surfaces ◽  
Voucher Specimens ◽  
Inoculation Procedure ◽  
White Mycelium ◽  
The University

Honeysuckle (Lonicera caprifolium L., family Caprifoliaceae) is a climbing shrub used in gardens to cover walls and supports. During the summer of 2003, severe outbreaks of a previously unknown powdery mildew were observed on this species in some gardens near Biella (northern Italy). The first symptoms included extensive chlorosis on leaves, followed by the appearance of white mycelium on the adaxial and abaxial leaf surfaces. As the disease progressed, infected leaves turned yellow and died. Conidia were hyaline, ellipsoidal, and measured 27.6 to 43.2 × 12.2 to 21.6 μm (average 35.7 × 17.6 μm). Foot cells were cylindric and appressoria lobed. Fibrosin bodies were not present. Cleistothecia were not observed during the growing season. The pathogen was identified as Oidium subgenus Pseudoidium (2). The inoculation procedure involved gently pressing diseased leaves onto leaves of healthy L. caprifolium plants. Three plants of L. caprifolium were used as replicates. Noninoculated plants served as control. Inoculated and noninoculated plants were maintained in a garden at temperatures ranging from 15 to 25°C. After 10 days, typical symptoms of powdery mildew developed on inoculated plants. Noninoculated plants did not show symptoms. To our knowledge, this is the first report of powdery mildew on L. caprifolium in Italy. The presence of powdery mildew on different species of Lonicera has been reported in several countries, particularly, Microsphaera miurae U. Braun on L. morowii A. Gray in Germany (1), M. lonicerae (DC.) Winter on L. peryclimenum L. in England (3), and M. lonicerae-ramosissimae on L. ramosissima Fr. & Sav. in Japan (4). The conidia of M. lonicerae are smaller than those of the Oidium sp. reported on L. caprifolium. Voucher specimens are available at DIVAPRA Collection at the University of Torino. References: (1) U. Braun. Mycotaxon 16:417, 1983. (2) U. Braun and S. Takamatsu. Schlechtendalia 4:1, 2000. (3) J. Robbins. Cecidology 15:15, 2000. (4) S. Tanda. Mycoscience 41:155, 2000.

scholarly journals First Report of Powdery Mildew on Euryops pectinatus in Italy

Plant Disease ◽  
2002 ◽  
Vol 86 (8) ◽  
pp. 920-920
Author(s):  
A. Garibaldi ◽  
A. Minuto ◽  
D. Bertetti ◽  
M. L. Gullino
Keyword(s):  
Powdery Mildew ◽  
Leaf Surface ◽  
Northern Italy ◽  
Growth Chamber ◽  
Growth Reduction ◽  
First Report ◽  
Similar Disease ◽  
Commercial Farms ◽  
White Mycelium ◽  
Sphaerotheca Fusca

Euryops pectinatus is grown in Italy for landscape use in parks and gardens. In 2001, severe outbreaks of a previously unknown powdery mildew were observed in commercial farms located in Albenga (northern Italy). All green parts (leaves, stems, and petioles) became covered with a white mycelium. Infections were particularly severe on the upper leaf surface. With progress of the disease, infected leaves turned yellow and died. The presence of powdery mildew infections on leaves and stems only rarely was linked to growth reduction. Conidia were hyaline, cylindric to slightly doliform, did not show fibrosin bodies, borne in chains, and measured 24 to 41 × 12 to 20 μm. Cleistothecia were not observed. The pathogen was identified as Oidium sp. subgen. Fibroidium (1). Pathogenicity was confirmed by gently pressing diseased leaves on leaves of healthy E. pectinatus plants. Inoculated plants were maintained in a growth chamber at 20 to 24°C. After 12 to 14 days, powdery mildew symptoms developed. A similar disease of E. pectinatus was observed in 1999 in California and identified as being caused by Podosphaera (Sphaerotheca) fusca (2). It is possible that the powdery mildew observed in Italy belongs to the same species, also considering that recently the two genera, Podosphaera and Sphaerotheca, have been unified in the genus Podosphaera (1). References: (1) U. Braun and S. Takamatsu. Schlechtendalia 4:1, 2000. (2) G. S. Saenz et al. Plant Dis. 84:1048, 2000.

scholarly journals First Report of Powdery Mildew Caused by Oidium Subgenus Pseudoidium on Salvia scabra in Italy

Plant Disease ◽  
2004 ◽  
Vol 88 (6) ◽  
pp. 682-682
Author(s):  
A. Garibaldi ◽  
A. Minuto ◽  
D. Bertetti ◽  
M. L. Gullino
Keyword(s):  
Powdery Mildew ◽  
The United States ◽  
Northern Italy ◽  
American Phytopathological Society ◽  
First Report ◽  
Experimental Station ◽  
Mature Leaves ◽  
Comprehensive Treatise ◽  
Erysiphe Polygoni ◽  
The University

Salvia scabra Thunb. is grown and used on the Italian Riviera as a potted plant and used in gardens. During the spring of 2003, severe outbreaks of a previously unknown powdery mildew were observed in a collection of Salvia spp. maintained at an experimental station at Albenga (northern Italy). Powdery mildew was observed only on S. scabra. Leaves were covered with white exophytic mycelia on both surfaces. As the disease progressed, infected leaves turned yellow and died. Conidia were single, hyaline, cylindric, and measured 21.3 to 35.5 × 12.5 to 22.5 μm (average 28.2 × 18.4 μm). Observations made with a light microscope revealed that foot cells were cylindric and appressoria lobed. Cleistothecia were not observed. The pathogen was identified as Oidium subgenus Pseudoidium (1,2), and pathogenicity was confirmed by gently pressing diseased leaves onto mature leaves of healthy, 40-day-old S. scabra plants. Five plants of S. scabra were used as replicates. Noninoculated plants served as controls. Inoculated and noninoculated plants were maintained in a growth chamber at 20°C. After 5 days, typical symptoms of powdery mildew developed on inoculated plants. Noninoculated plants did not show symptoms. To our knowledge, this is the first report of the presence of powdery mildew on S. scabra in Italy as well as in the world. Erysiphe polygoni DC. (Oidium subgenus Pseudoidium) and E. cichoracearum DC. (Oidium subgen us Reticuloidium) were previously reported as causal agents of powdery mildew on other species of Salvia (S. officinalis and S. sclarea) (3,4). Specimens of this disease are available at the DIVAPRA Collection at the University of Torino. References: (1) R. Belanger et al., eds. The Powdery Mildew A Comprehensive Treatise. The American Phytopathological Society, St Paul, MN, 2002. (2) U. Braun. Nova Hedwigia. 89:700, 1987. (3) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St Paul, MN, 1989. (4) A. Pisi and M. G. Bellardi. Inf. Fitopatol. 48(10):57, 1998.

scholarly journals First Report of Powdery Mildew Caused by Oidium Subgenus Pseudoidium on Mandevilla splendens in Italy

Plant Disease ◽  
2004 ◽  
Vol 88 (6) ◽  
pp. 682-682
Author(s):  
A. Garibaldi ◽  
A. Minuto ◽  
M. L. Gullino
Keyword(s):  
Powdery Mildew ◽  
Lower Surface ◽  
Northern Italy ◽  
Pathogenicity Test ◽  
American Phytopathological Society ◽  
First Report ◽  
Tropical Plant ◽  
Comprehensive Treatise ◽  
Young Leaves ◽  
The University

Mandevilla splendens (Hook.) Woodson is a tropical plant belonging to the Apocynaceae family and grown in Italy as an ornamental. It is generally potted and used to create small barriers on terraces and gardens. During February 2003, severe outbreaks of a previously unknown powdery mildew were observed in a commercial glasshouse located at Albenga (northern Italy) where 30% of the plants were affected by the disease. Infected young leaves were covered on both sides with white mycelia. Mycelia were more evident on the lower surface of older leaves. As the disease progressed, infected leaves turned reddish and eventually became yellow and died. Powdery mildew infections sometimes cause leaves to distort and have reduced growth. Conidia were hyaline, ellipsoid or cylindrical, sometimes appeared to adhere in chains, measured 9 to 15 × 14 to 28 μm (average 12 × 21 μm), and did not show fibrosin bodies. Foot cell was cylindric and appressorium lobed. Cleistothecia were not observed. The pathogen was identified as Oidium sp. subgenus Pseudoidium (1,2,3). Pathogenicity was confirmed by gently pressing diseased leaves onto young leaves of healthy, 1-year-old M. splendens plants grown in 3.5 liter pots. Three plants were inoculated, while three noninoculated plants served as controls. After inoculation, plants were maintained in a growth chamber at 18°C (12-h light, relative humidity >75%). After 60 days, powdery mildew symptoms were observed on inoculated plants. Noninoculated plants remained healthy. The pathogenicity test was carried out twice. To our knowledge, this is the first report of powdery mildew on M. splendens in Italy, as well as in the world. Specimens of this disease are available at the DIVAPRA Collection at the University of Torino. References: (1) R. Belanger et al., eds. The powdery mildew A comprehensive treatise. The American Phytopathological Society, St Paul, MN, 2002. (2) U. Braun. Nova Hedwigia, 89:700, 1987. (3) R. T. A. Cook et al. Mycol. Res. 101:975, 1997.

scholarly journals First Report of Powdery Mildew Caused by Erysiphe (Golovinomyces) orontii on Veronica spicata in Italy

Plant Disease ◽  
2006 ◽  
Vol 90 (6) ◽  
pp. 831-831
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
D. Minerdi ◽  
M. L. Gullino
Keyword(s):  
Powdery Mildew ◽  
Its Region ◽  
Lower Surface ◽  
Pathogenicity Test ◽  
Sphaerotheca Fuliginea ◽  
First Report ◽  
Golovinomyces Orontii ◽  
The Family ◽  
Blastn Analysis ◽  
White Mycelium

Veronica spicata (spike speedwell) is a perennial garden species belonging to the family Scrophulariaceae. During the summer through fall of 2004 and 2005, severe outbreaks of a previously unknown powdery mildew were observed in several gardens near Biella (northern Italy). Upper surfaces of leaves were covered with a white mycelium and conidia, and as the disease progressed, infected leaves turned yellow and died. Very rarely was the mycelium observed on the lower surface of leaves or on petioles and flowers. Foot cell was cylindric and measured 19.2 to 25.7 × 10.8 to 14.3 μm (average 21.9 × 12.0 μm). Conidia were hyaline, ellipsoid, brought in short chains (three conidia per chain), and measured 22.2 to 40.8 × 13.6 to 21.6 μm (average 30.1 × 17.0 μm). Conidiophores measured 45.5 to 74.0 × 10.4 to 11.0 μm (average 59.4 × 10.6 μm). Fibrosin bodies were absent. Cleistothecia were never observed on the samples collected. The ITS region (internal transcribed spacer) of rDNA was amplified using the primers ITS4/ITS6 (3) and sequenced. BLASTn analysis (1) of the 504 bp obtained showed an E-value of 0.0 with Erysiphe (Golovinomyces) orontii (2). The nucleotide sequence has been assigned GenBank Accession No. DQ386696. Pathogenicity was confirmed by gently pressing diseased leaves onto leaves of five healthy Veronica spicata plants. Five noninoculated plants served as controls. Inoculated and noninoculated plants were maintained in a greenhouse where temperatures ranged between 15 and 28°C. After 15 days, typical powdery mildew symptoms developed on inoculated plants. Noninoculated plants did not show symptoms. The pathogenicity test was carried out twice. To our knowledge, this is the first report of the presence of powdery mildew on V. spicata in Italy. Sphaerotheca fuliginea has been reported as the causal agent of powdery mildew on V. spicata (4). Specimens of this disease are available at DIVAPRA Collection, University of Torino. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) U. Braun. Nova Hedwigia 89:166, 1987. (3) D. E. L. Cooke and J. M. Duncan. Mycol. Res. 101:667, 1997. (4) B. Ing. Mycologist 4:125, 1990.

scholarly journals First Report of Powdery Mildew Caused by an Oidium sp. on Papaver nudicaule in Italy

Plant Disease ◽  
2004 ◽  
Vol 88 (6) ◽  
pp. 682-682
Author(s):  
A. Garibaldi ◽  
A. Minuto ◽  
D. Bertetti ◽  
M. L. Gullino
Keyword(s):  
Powdery Mildew ◽  
Northern Italy ◽  
Cut Flower ◽  
Plant Leaves ◽  
American Phytopathological Society ◽  
Voucher Specimen ◽  
First Report ◽  
Erysiphe Cruciferarum ◽  
Comprehensive Treatise ◽  
The University

Iceland poppy (Papaver nudicaule L.) is grown on the Italian Riviera for export as a cut flower and its importance in the industry is increasing. During the spring of 2003, severe outbreaks of powdery mildew that had not been reported previously, occurred in several commercial plantings grown outdoors in containers near Imperia in northern Italy. Mycelium was observed on all green organs of the plant (leaves, stems, and petioles). Both surfaces on the leaves were affected, and heavily colonized leaves were distorted. As the disease progressed, diseased leaves turned yellow and died. The disease did not affect the flowers. Conidia were hyaline, cylindric, and measured 10.8 to 29.8 × 16.8 to 48.0 μm (average 13.7 × 37.3 μm). Foot cells were cylindric and appressoria unlobed. Fibrosin bodies were not present, and cleistothecia were not observed. The pathogen was identified as Oidium sp. subgenus Pseudoidium (1,2). Pathogenicity was confirmed by gently pressing leaves with visible sporulation onto the leaves of five 90-day-old P. nudicaule plants that were healthy and free of symptoms. Five noninoculated healthy plants served as controls. Inoculated and noninoculated plants were maintained in a growth chamber at 15°C with a 12-h photoperiod. After 7 to 10 days, typical symptoms of powdery mildew developed on inoculated plants but not on noninoculated plants. Previously, Erysiphe cruciferarum Opiz ex L. Junell has been reported on P. nudicaule in all continents, and E. cichoracearum DC. and E. polygoni DC. have been reported in several countries, including Italy, as a causal agent of powdery mildew on other species of Papaver including P. rhoeas and P. strigosum. To our knowledge, this is the first report of powdery mildew caused by an Oidium sp. on P. nudicaule in Italy. The voucher specimen is kept in the department collection at the University of Torino. References: (1) R. Belanger et al., eds. The Powdery Mildew A Comprehensive Treatise. The American Phytopathological Society, St Paul, MN, 2002. (2) U. Braun. Nova Hedwigia. 89:700, 1987.

scholarly journals First Report of Powdery Mildew Caused by Leveillula taurica on Cynanchum kashgaricum in China

Plant Disease ◽  
2012 ◽  
Vol 96 (9) ◽  
pp. 1373-1373
Author(s):  
G. He ◽  
B. Xu ◽  
J. G. Song ◽  
L. L. Zhang ◽  
Z. Y. Zhao ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Morphological Characters ◽  
Taklimakan Desert ◽  
Its Sequence ◽  
Endangered Plant ◽  
Voucher Specimen ◽  
First Report ◽  
Leveillula Taurica ◽  
The Family ◽  
In The Wild

Cynanchum kashgaricum Liou f., belonging to the family Apocynaceae, is an endemic herbaceous perennial and extremely endangered plant species, only found in the wild in desert regions of Xinjiang, China (3), and is valuable for sand stabilization. In August 2010, a previously unknown and widespread powdery mildew disease was observed on C. kashgaricum growing in the Taklimakan Desert in Xinjiang, China. Disease symptoms included the appearance of a white mycelial coating on the upper surfaces of leaves, while the corresponding abaxial surfaces of infected leaves became chlorotic. As the disease progressed, the infected leaves turned yellow and necrotic. In this survey, the incidence of affected C. kashgaricum plants was 60%. On the basis of microscopic examination, the morphology of the fungus can be described as follows: the primary conidia of the fungus were lanceolate or clavate, with a pointed apex and rounded base, measuring 40.4 to 82.5 × 11.1 to 24.6 μm, with an irregular surface covered by warts; the secondary conidia varied in shape from subcylindrical to cylindrical, with rounded ends, and had lateral borders that were parallel to each other with rounded or truncate bases, measuring 40.5 to 73.5 × 11.2 to 23.9 μm. The ascomata were nearly gregarious and globe-shaped, of dust-colored appearance, and 113 to 267 μm in diameter; they were immersed in dense mycelial tomentum with numerous asci (usually 10 to 18 per ascoma). Numerous, well-developed appendages were present on the lower half of the ascomata; these appendages were irregularly branched and their length was 0.15 to 0.3 times the diameter of the ascomata. The asci were stalked, long or wide ellipsoidal in shape, and 93 to 140 × 27.6 to 52.9 μm. The asci usually contained two ellipsoidal ascospores 24.5 to 49.5 × 18.3 to 29.5 μm. On the basis of morphologic characteristics, the fungus was identified as Leveillula taurica (2). A voucher specimen of the fungus under the identifier HMTU09021 was deposited in the Mycological Herbarium of Tarim University (HMTU). To verify the identity of the fungus, the internal transcribed spacer (ITS) rDNA was amplified and sequenced, and the sequences were deposited as GenBank Accession No. JN861731. Comparison with sequences in the GenBank database revealed that the ITS sequence showed 100% homology with the sequence of L. taurica on Capsicum annuum (Accession No. GQ167201) and Lepidium latifolium (Accession No. AB044349). Thus, the pathogen was identified as L. taurica on the basis of the anamorphic and teleomorphic morphological characters and the ITS sequence. To our knowledge, while L. taurica infection in plants of the family Apocynaceae has been reported around the world (1), in east Asia only a single report of C. glaucum infection in this genus has occurred, in Afghanistan (1). This is the first report of L. taurica infection of C. kashgaricum. Outbreaks of this powdery mildew could not only threaten growth of the endangered plant but also accelerate local ecological deterioration. References: (1) K. Amano. Host Range and Geographical Distribution of the Powdery Mildew Fungi, 2nd ed. Japan Scientific Societies Press, Tokyo, Japan, 1986. (2) U. Braun. A Monograph of the Erysiphales (Powdery Mildews). Nova Hedwigia Beiheft 89:1, 1987. (3) F. Ying et al. Acta Bot. Boreali-Occidentalia Sin. 23:263, 2003.

scholarly journals First Report of Powdery Mildew on Azalea Cv. Mollis (Rhododendron japonicum × R. molle) in Italy

Plant Disease ◽  
2002 ◽  
Vol 86 (3) ◽  
pp. 329-329
Author(s):  
A. Garibaldi ◽  
G. Gilardi ◽  
D. Bertetti ◽  
M. L. Gullino
Keyword(s):  
United Kingdom ◽  
Powdery Mildew ◽  
Northern Italy ◽  
First Report ◽  
The United Kingdom ◽  
Powdery Mildews ◽  
Initial Symptoms ◽  
Leaf Surfaces ◽  
Microscopy Examination ◽  
Selection Of

Rhododendron cultivation has a long history in northern Italy, where a wide selection of varieties and hybrids are grown. In summer 2001, a previously unknown powdery mildew was observed on azalea cv. Mollis (Rhododendron japonicum × R. molle) grown in several gardens in the province of Biella. Initial symptoms included chlorotic spots, followed by white fungal mycelia on both leaf surfaces. Eventually, infected leaves turned reddish and dropped prematurely. Fruit were also infected. On infected tissues, dark brown-to-black spherical cleistothecia developed, alone or in groups. The teleomorph was identified by light microscopy examination of cleistothecia. Cleistothecia measured 110 to 140 µm and were dark brown. They contained four to eight stalked or sessile asci that measured 35 to 45 µm × 40 to 55 µm, each containing six to eight ascospores. Ascospores were ellipsoid to ovoid and measured 12 to 18 µm × 20 to 25 µm. Cleistothecial characteristics were consistent with those described for Microsphaera azaleae but were different from those of the recently described species M. digitata reported in Belgium (1). The presence of conidia was rare in the specimens, so the anamorph could not be identified. To our knowledge, this is the first report of M. azaleae in Italy, but three outbreaks of powdery mildew on rhododendron were first reported in the United Kingdom on plants grown in glasshouses in the mid-1950s, 1969 and 1973 (1). Outdoors, powdery mildew was first reported on rhododendron in Europe in 1981. M. azaleae has been identified as the causal agent of rhododendron powdery mildew in the United Kingdom, Germany, and Switzerland (1). In most cases the disease is readily controlled by regular application of fungicides commonly used against powdery mildews of other crops. Reference: (1) A. J. Inman et al. J. Phytopathol. 148:17, 2000.

scholarly journals First Report of Powdery Mildew Caused by Podosphaera aphanis var. aphanis on Potentilla fruticosa in Italy

Plant Disease ◽  
2005 ◽  
Vol 89 (12) ◽  
pp. 1362-1362
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
M. L. Gullino
Keyword(s):  
United States ◽  
Powdery Mildew ◽  
The United States ◽  
Pathogenicity Test ◽  
First Report ◽  
Potentilla Fruticosa ◽  
Erysiphe Polygoni ◽  
Voucher Specimens ◽  
White Mycelium ◽  
Sphaerotheca Macularis

Potentilla fruticosa L. (bush cinquefoil), belonging to the family Rosaceae, is an ornamental plant used in parks and gardens. During the spring and summer of 2005, severe outbreaks of a previously unknown powdery mildew were observed in several private gardens located near Biella (northern Italy). The adaxial and abaxial surfaces of leaves as well as the stems were covered with white mycelium. Buds and flowers also were affected. As disease progressed, infected leaves turned yellow and dehisced. Conidia formed in chains and were hyaline, ovoid, and measured 24.0 to 36.0 × 15.8 to 24.0 μm (average 30.1 × 20.0 μm). Fibrosin bodies were present. Chasmothecia were numerous, sphaerical, amber colored, and diameters ranged from 84.0 to 98.4 μm (average 90.4 μm). Each chasmothecium contained one ascus with eight ascospores. Ascospores measured 26.5 to 27.2 × 13.2 to 15.6 μm (average 26.8 × 14.0 μm). On the basis of its morphology, the causal agent was determined to be Podosphaera aphanis (Wallr.) U. Braun & S. Takamatsu var. aphanis U. Braun (1). Pathogenicity was confirmed through inoculations by gently pressing diseased leaves onto leaves of healthy P. fruticosa plants. Three plants were inoculated. Three noninoculated plants served as a control. Plants were maintained at temperatures ranging from 12 to 23°C. Ten days after inoculation, typical symptoms of powdery mildew developed on inoculated plants. Noninoculated plants did not show symptoms. The pathogenicity test was carried out twice. To our knowledge, this is the first report of powdery mildew on P. fruticosa in Italy. Erysiphe polygoni D.C. and Sphaerotheca macularis (Wallr.:Fr.) Lind were observed in the United States on P. fruticosa (2), while in Japan, the presence of S. aphanis var aphanis was reported (3). Voucher specimens are available at the AGROINNOVA Collection, University of Torino. References: (1) U. Braun and S. Takamatsu. Schlechtendalia 4:1, 2000 (2) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St Paul, MN, 1989. (3) S. Tanda et al. J. Agric. Sci. 39:258, 1995.

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