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 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 (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 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.

scholarly journals First Report of Powdery Mildew, Caused by an Oidium sp., on Poinsettia in California

Plant Disease ◽  
1998 ◽  
Vol 82 (1) ◽  
pp. 128-128 ◽  
Author(s):  
S. T. Koike ◽  
G. S. Saenz
Keyword(s):  
United States ◽  
Powdery Mildew ◽  
Pacific Northwest ◽  
The United States ◽  
Euphorbia Pulcherrima ◽  
American Phytopathological Society ◽  
First Report ◽  
The Pacific ◽  
Uninoculated Control ◽  
Alternative Identification

In December 1996 and January 1997, powdery mildew was observed on potted poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch) plants in Monterey County, CA. Mycelia were observed on stems, petioles, mature and immature leaves, and bracts. Severely diseased leaves became twisted and bent and senesced prematurely. The white mycelia were conspicuous, epiphytic, and amphigenous; hyphae measured 4.6 to 6.9 μm in diameter. Growth initially was in patches but eventually became effused. Appressoria were slightly lobed to lobed and sometimes opposite. Conidiophore foot cells were cylindrical, sometimes bent at the base, and slightly flexuous to flexuous. Foot cells measured 30.0 to 46.2 μm × 5.8 to 6.9 μm and were followed by one to two shorter cells. Conidia were cylindrical to slightly doliform and measured 25.4 to 32.3 μm × 11.6 to 18.5 μm. The length-to-width ratios of conidia generally were greater than 2.0. Conidia were produced singly, placing the fungus in the Pseudoidium-type powdery mildew group. Conidia germinated at the ends, and no fibrosin bodies were observed. Cleistothecia were not found. The fungus was identified as an Oidium species. Pathogenicity was demonstrated by gently pressing infected leaves having abundant sporulation onto leaves of potted poinsettia plants (cvs. Freedom Red, Peter Star Marble, and Nutcracker White), incubating the plants in a moist chamber for 48 h, and then maintaining plants in a greenhouse. After 12 to 14 days, powdery mildew colonies developed on the inoculated plants, and the pathogen was morphologically identical to the original isolates. Uninoculated control plants did not develop powdery mildew. This is the first report of powdery mildew on poinsettia in California. This fungus appears similar to Microsphaera euphorbiae but has longer, slightly flexuous foot cells that do not match the description for M. euphorbiae (1,2). An alternative identification would be Erysiphe euphorbiae; however, there are no available mitosporic descriptions for morphological comparisons (1,2). In the United States, powdery mildew of poinsettia previously has been reported in various states in the Pacific Northwest, Midwest, and Northeast. References: (1) U. Braun. Beih. Nova Hedwigia 89:1, 1987. (2) D. F. Farr et al. 1989. Fungi on Plants and Plant Products in the United States. American Phytopathological Society, St. Paul, MN.

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 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 the Powdery Mildews Leveillula taurica and Podosphaera pannosa on Rose Periwinkle in the United States

Plant Disease ◽  
2014 ◽  
Vol 98 (6) ◽  
pp. 848-848 ◽  
Author(s):  
M. K. Romberg ◽  
A. H. Kennedy ◽  
M. Ko
Keyword(s):  
United States ◽  
Powdery Mildew ◽  
Consensus Sequence ◽  
The United States ◽  
Infected Leaf ◽  
Adaxial Side ◽  
First Report ◽  
Leveillula Taurica ◽  
Powdery Mildews ◽  
External Hyphae

In April 2013, unthrifty rose periwinkle (Catharanthus roseus (L.) G. Don) from a residential garden in Mililani, HI, was sent to the Hawaii Department of Agriculture. Symptoms, present on all plants, included leaf chlorosis, defoliation, and premature flower drop with necrotic spots on the adaxial side of leaves corresponding to patches of grayish mildew-like growth on the abaxial side. Samples were collected and sent to USDA PPQ National Identification Services (NIS) for confirmation. At NIS, stereoscope examination of the plants revealed two distinct powdery mildews. One, on the stems and leaves, had dimorphic conidia, with lanceolate primary (54 to 72 × 14 to 22 μm) and cylindrical secondary conidia (49 to 75 × 11 to 21 μm) (n = 25 for each), both with a reticulate surface. This fungus was identified morphologically as Leveillula taurica (Lév.) G. Arnaud (1). The second powdery mildew appeared confined to the sepals and petals. The external hyphae of this fungus produced upright chains of cylindrical to ovoid conidia (up to eight per chain), which contained fibrosin bodies and measured 22 × 12 μm (n = 50) with straight foot cells averaging 43 μm long, placing this fungus in the genus Podosphaera Kunze (1). Plants containing both fungi were accessioned as BPI892677 in the US National Fungal Collection. For molecular characterization, genomic DNA of the Podosphaera was obtained by scraping conidia from a petal and extracting with Thermo Scientific's Lyse and Go PCR Reagent. DNA of the Leveillula was extracted from 5 mm2 of infected leaf using Qiagen's Plant mini kit. The ITS region of each fungus was amplified and sequenced directly with primers ITS1F and ITS4. Each consensus sequence was created from manually edited chromatograms, searched against NCBI's GenBank using MegaBLAST and phylogenetically analyzed in MEGA5.2 under maximum parsimony (MP) in context with most similar hits and representatives from phylogenetic studies (2,3). Sequences from types of these fungi are not available for comparison. The resulting Podosphaera phylogeny grouped the Podosphaera suspect (GenBank KF703448) within a clade of P. pannosa (e.g., AB525938; bootstrap = 90). The Leveillula phylogeny grouped the Leveillula suspect (KF703447) within a clade (bootstrap = 88) of L. taurica (e.g., AB044346), L. chrozophorae (AB044346), and L. elaeagni (AB048350). Although the ITS sequences of these taxa are phylogenetically indistinguishable, morphological characters differentiate each species and the suspect as L. taurica (1). L. taurica has been recorded on C. roseus in India and Korea (1). This is the first report of L. taurica on C. roseus in the United States. This is the first report of P. pannosa on C. roseus worldwide. P. pannosa is commonly known as a powdery mildew of Rosaceae hosts, and has also been reported on hosts in the Anacardaciae and Oleaceae (1). P. pannosa represents the second Podosphaera species reported on any member of the Apocynaceae, with P. sparsa reported on other Apocynaceae genera (1). The presence of two powdery mildew genera on different parts of the same plant could cause multiple forms of damage and impact the production of this popular landscape ornamental plant. References: (1) U. Braun and R. T. A. Cook. Taxonomic Manual of the Erysiphales (Powdery Mildews), CBS Biodiversity Series No. 11. CBS, Utrecht, Netherlands, 2012. (2) S. A. Khodoparast et al. Mycol. Res. 105:909, 2001. (3) S. Takamatsu et al. Persoonia 24:38, 2010.

scholarly journals First Report of Powdery Mildew Caused by Golovinomyces orontii on Corn-Salad in the United States

Plant Disease ◽  
2005 ◽  
Vol 89 (6) ◽  
pp. 686-686 ◽  
Author(s):  
S. T. Koike ◽  
G. S. Saenz
Keyword(s):  
United States ◽  
Powdery Mildew ◽  
Mycelial Growth ◽  
Leaf Growth ◽  
The United States ◽  
First Report ◽  
Powdery Mildews ◽  
Leaf Surfaces ◽  
Germ Tubes ◽  
Symptoms And Signs

Corn-salad or lamb's lettuce (Valerianella locusta) is a specialty leafy green, annual vegetable that is grown commercially in California for use in salads. During the summer (June through August) of 2004, field plantings in coastal California (Monterey County) showed symptoms and signs of a powdery mildew. White, ectophytic mycelia and conidia were present on leaves and petioles. Extensively colonized leaves were slightly twisted and later developed a tan necrosis. Mycelial growth was spread out, flat, sometimes dense, and colonized both sides of the leaf. Growth was more extensive on the upper leaf surfaces. Hyphae were 5 to 7.5 μm wide with nipple-shaped appressoria. Conidiophores were straight and had foot cells that were simple, mostly curved, measured 50 to 65 × 10 to 12.5 μm, and followed by two to three cells of equal size. Conidia developed in short chains. Conidia were cylindric to doliform, measured 27.5 to 32.5 × 15 to 17.5 μm, and lacked fibrosin bodies. Conidial length-to-width ratios were usually less than or equal to 2.0. Conidia germinated at the ends (cichoracearum-type) and had germ tube lengths that ranged from short to 1.0 to 1.5 times the length of the conidium; germ tubes had swollen tips. Cleistothecia were not observed. On the basis of these characteristics, the fungus is identified as Golovinomyces (Erysiphe) orontii(Cast.) Heluta (1). To demonstrate pathogenicity, heavily colonized corn-salad leaves from commercial plantings were collected and gently pressed onto leaves of potted corn-salad plants. Plants were then maintained in a greenhouse (22 to 24°C). After 8 to 10 days, symptoms and signs of powdery mildew developed on the foliage of inoculated plants, and the pathogen morphology matched that of the originally observed pathogen. Noninoculated control plants did not develop powdery mildew. To our knowledge, this is the first report of powdery mildew of corn-salad caused by G. orontii in the United States. This corn-salad disease has been reported from a number of countries in Europe (2). Because the presence of powdery mildew on the harvested foliage made the leaves unmarketable, part of the crop could not be sold. References: (1) U. Braun. Nova Hedwigia 89:1, 1987. (2) U. Braun. The Powdery Mildews (Erysiphales) of Europe. Gustav Fischer Verlag, Jena, Germany, 1995.

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 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.

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