scholarly journals First Report of Powdery Mildew Caused by Sphaerotheca fusca on Tomatillo in California

Plant Disease ◽  
1998 ◽  
Vol 82 (6) ◽  
pp. 711-711 ◽  
Author(s):  
S. T. Koike ◽  
R. F. Smith
Keyword(s):  
Powdery Mildew ◽  
Fungal Growth ◽  
Premature Senescence ◽  
First Report ◽  
Powdery Mildew Disease ◽  
Salinas Valley ◽  
Germ Tubes ◽  
Husk Tomato ◽  
Sphaerotheca Fusca ◽  
Commercial Field

Tomatillo or husk tomato (Physalis ixocarpa Brot.) is an annual Solanaceous bush grown for its fruit, which are harvested when the fruit fill the enlarged calyx and are used primarily in Hispanic cooking. In the summer of 1997, commercial field-grown tomatillo in the Salinas Valley (Monterey County) was severely affected by a powdery mildew disease. Fungal growth was found on leaves, petioles, and calyces and resulted in twisting, desiccation, and premature senescence of the tissues. The mycelium was white to gray, ectophytic, amphigenous, and effuse. Mycelial appressoria were indistinct. Conidiophore foot cells were straight, cylindric, measured 36.1 to 61.1 µm (mean 47.0) × 11.1 to 13.9 µm (mean 11.7), and were followed by 1 to 3 shorter cells. Doliform conidia were formed in chains and measured 25.0 to 50.0 µm (mean 32.5) × 11.1 to 22.2 µm (mean 17.7). The length-to-width ratios of conidia generally were less than 2.0, and fibrosin bodies were present. Germ tubes usually were laterally inserted, lacked conspicuous appressoria, and were of the pannosa-type. Cleistothecia were not observed. Based on these characters, the fungus was identified as Sphaerotheca fusca (Fr.) Blumer, Beitr. Krypt.-Fl. Schweiz (1). Pathogenicity was confirmed by gently pressing infected leaves onto leaves of potted tomatillo. Inoculated plants were kept in a chamber at 100% humidity for 48 h, and then maintained in a greenhouse. Powdery mildew developed on inoculated plants after 12 to 14 days, while uninoculated plants did not develop disease. The experiment was conducted a second time and the results were the same. This is the first report of a powdery mildew disease of tomatillo in California. Reference: (1) U. Braun. Nova Hedwigia 89:1, 1987.

First Report of Powdery Mildew of Fringed Willowherb (Epilobium ciliatum) Caused by Podosphaera epilobii in North America

2007 ◽  
Vol 8 (1) ◽  
pp. 41
Author(s):  
Steven T. Koike ◽  
Dean A. Glawe
Keyword(s):  
North America ◽  
Powdery Mildew ◽  
First Report ◽  
Powdery Mildew Disease ◽  
Salinas Valley ◽  
Ornamental Crops

Description and first report of powdery mildew caused by Podosphaera epilobii on E. ciliatum in North America are presented in this brief. The weed is commonly found in California's Salinas Valley (Monterey Co.). Confirmation of the powdery mildew disease indicates that this weed will not be a source of the powdery mildew diseases that affect nearby vegetable and ornamental crops. Accepted for publication 4 September 2007. Published 12 November 2007.

scholarly journals Powdery Mildew of Spearmint Caused by Erysiphe orontii in California

Plant Disease ◽  
1999 ◽  
Vol 83 (4) ◽  
pp. 399-399 ◽  
Author(s):  
S. T. Koike ◽  
G. S. Saenz
Keyword(s):  
Powdery Mildew ◽  
Fungal Growth ◽  
The State ◽  
Conidial Germination ◽  
Mentha Spicata ◽  
First Report ◽  
Humidity Chamber ◽  
Monterey County ◽  
Germ Tubes

In 1997 and 1998, the white fungal growth of a powdery mildew was observed on leaves and stems of both nursery and landscape spearmint (Mentha spicata) growing in coastal California (Monterey County). Mycelia were conspicuous, amphigenous, and epiphytic with indistinct to nipple-shaped appressoria. Conidiophore foot cells were cylindrical, straight, nonconstricted at the base, 61 to 92 μm × 11 to 14 μm in size, and were followed by 1 to 3 cells. Doliiform conidia, which were borne in chains of at least 3 to 5 conidia, measured 28 to 33 μm × 17 to 22 μm. Catenate conidia had sinuate edge lines. Conidia lacked fibrosin bodies. Upon germination, conidia produced germ tubes that were mostly apically inserted and ended in club-shaped appressoria, which fit Braun's Cichoracearum-type of conidial germination (1). Cleistothecia were not observed. Based on these features, the pathogen was identified as Erysiphe orontii Cast. (1). Pathogenicity was demonstrated by gently pressing diseased leaves onto leaves of potted spearmint, incubating plants in a humidity chamber for 48 h, then maintaining plants in a greenhouse. The powdery mildew that later developed was morphologically identical to the original isolates. While powdery mildew on spearmint has been observed previously in the state, this is the first report of the disease and first characterization of the pathogen for California. Reference: (1) U. Braun. Beih. Nova Hedwigia 89:1, 1987.

scholarly journals First Report of Powdery Mildew Caused by Oidium araliacearum on Ivy in California

Plant Disease ◽  
1998 ◽  
Vol 82 (1) ◽  
pp. 127-127 ◽  
Author(s):  
G. S. Saenz ◽  
S. T. Koike
Keyword(s):  
Powdery Mildew ◽  
Fungal Growth ◽  
University Of California ◽  
Accession Number ◽  
Hedera Helix ◽  
Moist Chamber ◽  
First Report ◽  
The University ◽  
Germ Tubes ◽  
English Ivy

Powdery mildew was observed on English ivy (Hedera helix L.) in Berkeley, CA, in the spring of 1997. Fungal growth was ectophytic and amphigenous on leaves and petioles and caused slight reddening and buckling of leaves. The mycelium was white, effuse to dense, and had hyphal diameters of 3.5 to 6.9 μm. Appressoria were nipple-shaped to lobed, and sometimes were opposite. The foot cells of the conidiophores were cylindric, sometimes slightly flexuous, and were 18.5 to 30.0 × 6.9 to 9.2 μm in diameter. The foot cells were followed by 1 or 2 cells. When only one cell followed the foot cell, this cell was longer and slightly wider than the foot cell and measured 20.8 to 46.2 × 6.9 to 9.2 μm. When two cells followed the foot cell, these cells were of similar length to the foot cell, with the second cell usually shorter. Conidia were formed singly, were cylindric to slightly doliiform, and measured 32.0 to 44.0 × 11.5 to 19.0 μm. Fibrosin bodies were not observed. Conidia germinated at the ends and germ tubes terminated in lobed appressoria, placing this fungus in the Polygoni-type germination category (2). Cleistothecia were not observed. Based on these characters, the fungus was identified as Oidium araliacearum U. Braun & E. Oehrens B. A specimen was deposited with the University of California at Berkeley herbarium (accession number UC1713247). Pathogenicity was confirmed by gently pressing infected leaves onto leaves of various stages of maturity on ivy vines (3 to 4 vines per plant; 4 plants). Inoculated plants were kept in a moist chamber for 48 h, and then maintained in a greenhouse. Powdery mildew developed on inoculated plants, primarily on leaves of intermediate maturity, after 14 days, while uninoculated plants did not develop disease. Phyllactinia guttata is the only other powdery mildew recorded on English ivy (2). O. araliacearum differs from P. guttata in conidial shape (cylindric vs clavate), germination habit (end vs side of conidia), and asexual genus (Oidium vs Ovulariopsis) (2). Previous to this report, O. araliacearum was described only on Pseudopanax valdiviensis, another Araliaceae plant, in Chile (1). This is the first report of a powdery mildew disease of ivy in California, and the first report of Hedera helix as a host of O. araliacearum. References: (1) U. Braun. Mycotaxon 25:259, 1986. (2) U. Braun. Nova Hedwigia 89:1, 1987.

scholarly journals First Report of Powdery Mildew, Caused by Erysiphe cruciferarum, on Broccoli Raab in California

Plant Disease ◽  
1997 ◽  
Vol 81 (9) ◽  
pp. 1093-1093 ◽  
Author(s):  
S. T. Koike ◽  
G. S. Saenz
Keyword(s):  
Powdery Mildew ◽  
Disease Incidence ◽  
Width Ratio ◽  
First Report ◽  
Erysiphe Cruciferarum ◽  
Salinas Valley ◽  
Inoculation Procedure ◽  
Uninoculated Control ◽  
Test Plants ◽  
Commercial Field

Broccoli raab (Brassica rapa subsp. rapa), also known as rappini, is a leafy vegetable that is widely grown in Europe and has in recent years become an important crop in coastal California. During summer months in the Salinas Valley (Monterey County) in California, powdery mildew was observed on commercial field and greenhouse-grown plants. White ectophytic mycelial and conidial growth was present on leaves, causing chlorosis, and also developed on stems. Mycelia were amphigenous, in patches, often spreading to become effused. Appressoria were lobed and conidiophores were straight. Foot cells were cylindrical, measured 18 to 26 × 7 to 10 μm, and were followed by one to two cells of variable length. Conidia were produced singly, were cylindrical, and measured 35 to 50 × 12 to 21 μm with a length-to-width ratio greater than 2. No fibrosin bodies were observed in the conidia, and conidia germinated at the ends. Cleistothecia were not observed. The fungus was identified as Erysiphe cruciferarum Opiz ex Junell (1). Pathogenicity was demonstrated by gently pressing infected leaves having abundant sporulation onto leaves of potted broccoli raab (cv. Spring Raab), incubating the plants in a moist chamber for 48 h, and then maintaining plants in a greenhouse. After 10 to 13 days, powdery mildew colonies developed on the test plants. Uninoculated control plants did not develop powdery mildew. With the same inoculation procedure, potted broccoli (Brassica oleracea subsp. botrytis cv. Greenbelt) also became infected by the broccoli raab isolates. This is the first report characterizing this pathogen on broccoli raab in the state. Disease incidence and severity in field-planted crops were low, but greenhouse-grown plants became severely infected. Reference: (1) U. Braun. Beih. Nova Hedwigia 89:1, 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.

First Report of Powdery Mildew of Coreopsis Species Caused by Golovinomyces cichoracearum in the Pacific Northwest

2006 ◽  
Vol 7 (1) ◽  
pp. 57
Author(s):  
Dean A. Glawe ◽  
Gary G. Grove ◽  
Mark Nelson
Keyword(s):  
Powdery Mildew ◽  
Pacific Northwest ◽  
Causal Agent ◽  
Diagnostic Features ◽  
First Report ◽  
The Pacific ◽  
Powdery Mildew Disease ◽  
Golovinomyces Cichoracearum

In 2005, the authors encountered a previously unreported powdery mildew disease of Coreopsis verticillata L. (whorled tickseed) ‘Zagreb’ and C. auriculata L. (lobed tickseed) ‘Nana’ in central Washington and determined the causal agent to be Golovinomyces cichoracearum (DC.) VP Gelyuta. This report documents the occurrence of G. cichoracearum on Coreopsis species in the Pacific Northwest, and describes diagnostic features of the disease and causal agent. Accepted for publication 2 March 2006. Published 5 April 2006.

scholarly journals First Report of Podosphaera aphanis Causing Powdery Mildew on Wild Blackberry Species (Rubus spp.) in Mexico

Plant Disease ◽  
2021 ◽  
Author(s):  
Alma Rosa Solano-Báez ◽  
Santos Gerardo Leyva-Mir ◽  
Moises Camacho-Tapia ◽  
Alfonso Arellano Victoria ◽  
Geremias Rodríguez-Bautista ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Powdery Mildew ◽  
Primary Source ◽  
Morphological Characters ◽  
Morphological Data ◽  
Wild Populations ◽  
First Report ◽  
Voucher Specimens ◽  
New Varieties ◽  
Germ Tubes

Wild blackberry species (Rubus spp. L.; Rosaceae) represents an invaluable source of genes for the generation of new varieties, but also serve as a primary source of disease inoculum. During April of 2020, symptoms of powdery mildew were observed on four populations of wild blackberry species located in the states of Chiapas (16°59'11"N, 92°59'07"W; 16°47'08"N, 92°31'05"W) and Michoacán (19°37'17"N, 100°08'59"W; 19°29'25"N, 101°32'54"W), Mexico. Signs of the pathogen were white powdery masses mainly on the top of new shoots. Symptoms included yellowing, necrosis, and early defoliation of the plants. Hyphae were tin-walled, hyaline, smooth, and 4.0–9.0 mm wide. Appressoria were indistinct -to- nipple-shaped. Conidiophores (n=30, 75–225 × 10.5–13.5 μm) were straight, and unbranched with cylindrical foot cells (n=30, 31.5–158 × 8–13.5 μm), straight, somewhat widening upwards, followed by 1–3 shorter cells. Conidia (n=100; 25.5–38.5 × 9.5–22.5 μm) were catenulate, ellipsoid-ovoid -to- doliiform, containing fibrosin bodies (in 3% KOH). Germ tubes (n=30, 13.5–40.5 × 4.5 μm) emerged laterally, and were unbranched with slightly swollen tips. Chasmothecia were not found. Morphological characters of the fungus in all samples corresponded to the previous descriptions of Podosphaera aphanis by Braun and Cook (2012) and Stevanovi´c et al. (2020). Voucher specimens were deposited in the Department of Agricultural Parasitology Herbarium at the Chapingo Autonomous University under accessions UACH421, UACH423, UACH425, UACH426. To confirm the species identification, the internal transcribed spacer (ITS) of one sample was amplified using the primers ITS5 (White et al. 1990) and P3 (Kusaba and Tsuge, 1995) and sequenced. The sequence was deposited in GenBank (accession number MW988591). A phylogenetic analysis using Bayesian inference and maximum likelihood was performed (Hernández-Restrepo et al. 2018) and included other Podosphaera species (Takamatsu et al. 2010). The sequence from the isolate UACH426 clustered with the strain MUMH1871 of P. aphanis forming a definite clade and remained as a sister taxon of P. pannosa. Pathogenicity was verified through inoculation by gently dusting conidia from one powdery mildew patch onto leaves of five healthy blackberry plants of each specie. The same number of noninoculated plants served as controls. All plants were maintained in a greenhouse at 25–30°C with 75% relative humidity. All inoculated plants developed powdery mildew symptoms after 12 days, whereas no symptoms were observed on noninoculated plants. The fungus recovered from the inoculated plants was morphologically identical to that originally observed on diseased blackberry plants, demonstrating the pathogenicity of the fungus. Based on morphological data and phylogenetic analysis, the fungus was identified as P. aphanis. This fungus has been reported to cause powdery mildew on blackberry plants in Serbia (Stevanovi´c et al. 2020). This is the first report of P. aphanis causing powdery mildew on wild backberry species in Mexico according to Farr and Rossman (2021). The primary source of inoculum of powdery mildew for commercial plantings is wild blackberry plants from noncultivated areas and may warrant control of wild populations.

scholarly journals First Report of Powdery Mildew Caused by Golovinomyces biocellatus on Peppermint in California

Plant Disease ◽  
2010 ◽  
Vol 94 (2) ◽  
pp. 276-276 ◽  
Author(s):  
D. B. Marcum ◽  
K. Perez ◽  
R. M. Davis
Keyword(s):  
Powdery Mildew ◽  
Fungal Growth ◽  
Universal Primers ◽  
Mentha Piperita ◽  
Exact Match ◽  
First Report ◽  
Plastic Bag ◽  
The One ◽  
Shasta County ◽  
Disease Free

In August of 2009, powdery mildew was observed on peppermint (Mentha piperita L.) in several commercial fields in the Fall River Valley of eastern Shasta County, California. Plant growth was apparently reduced by the disease, but its impact on yield was unknown. White fungal growth was restricted to the adaxial surfaces, where colonies were thin and effused. Heavily infected leaves developed a reddish tint as growth prematurely ceased. Doliform conidia ([26.6-] 29.2 [-31.7] × [13.2-] 15.6 [-16.8] μm) were produced in chains of approximately six conidia. Foot cells were cylindrical ([41.3-] 55.2 [-75.0] × [11.2-] 12.0 [-12.8] μm). Immature chasmothecia were yellowish brown and approximately 100.0 μm in diameter with flexuous, mycelium-like appendages up to 200 μm long. All these features were consistent with those of Golovinomyces biocellatus. Asci were not observed. To confirm the identity of the fungus, nuclear rDNA internal transcribed spacer (ITS) regions were amplified by PCR with universal primers ITS4 and ITS5. The sequence (537 bp) was an exact match for several submissions of G. biocellatus in GenBank (e.g., Accession No. EU035602, a sequence of the fungus from mint in Australia [1]). Pathogenicity was confirmed by brushing spores from naturally infected leaves onto three rooted cuttings of M. piperita ‘Black Mitchum’. After the plants were covered with a plastic bag for 36 h to maintain high humidity, they were kept on a greenhouse bench at 23 to 28°C. Three noninoculated plants, which served as controls, were placed in another greenhouse in similar conditions. The experiment was repeated once. All inoculated plants developed signs of powdery mildew within 7 days of inoculation whereas noninoculated plants remained disease free. The fungus on inoculated leaves was morphologically indistinguishable from the one used to inoculate the plants. To our knowledge, this is the first report of G. biocellatus on peppermint in California. References: (1) J. R. Liberato and J. H. Cunnington. Australas, Plant Dis. Notes 2:38, 2007.

scholarly journals First Report of Powdery Mildew of Parsley Caused by Erysiphe heraclei in Florida

Plant Disease ◽  
2007 ◽  
Vol 91 (4) ◽  
pp. 461-461 ◽  
Author(s):  
R. Raid ◽  
C. Miller ◽  
K. Pernezny
Keyword(s):  
Powdery Mildew ◽  
Fungal Pathogens ◽  
Fungal Growth ◽  
Leaf Tissue ◽  
Signs And Symptoms ◽  
Climatic Conditions ◽  
Petroselinum Crispum ◽  
First Report ◽  
Dark Green ◽  
Vegetable Farm

Parsley (Petroselinum crispum (Mill.) Nym. ex A.W. Hill) is an important leaf crop in the Everglades Agricultural Area of southern Florida. During the spring of 2005 and 2006, disease signs and symptoms resembling those incited by powdery mildew were observed on parsley at a commercial vegetable farm located 15 km east of Belle Glade. Symptoms consisted of leaf chlorosis, particularly in the dense lower canopy, and desiccation of affected tissue. A dense, white-to-light gray fungal growth was visible macroscopically on the surface of affected leaf tissue. Microscopic examinations revealed ectophytic hyphae with lobed appressoria and hyaline, straight conidiophores bearing single conidia. Conidia were short-cylindrical to cylindrical, measured 33 to 44 μm long and 13 to 16 μm wide, and lacked fibrosin bodies. Conidiophore foot cells were also cylindrical, straight, and measured 27 to 37 × 9 to 10 μm. Ascocarps of the teleomorph were not observed. The fungus closely matched the description of Erysiphe heraclei DC, a pathogen previously reported as attacking parsley on the U.S. West Coast (1,2). Pathogenicity was verified by inoculating adaxial leaf surfaces of 12 plants (cv. Dark Green Italian) with conidia collected from infected tissue by using a small brush. Inoculated plants and 12 noninoculated plants were lightly misted, held in a moist chamber for 48 h (22°C), and then incubated in a growth chamber for 4 weeks at 22°C with a photoperiod of 16 h. Symptoms that developed on inoculated plants were similar to those observed in the field, with no symptoms evident on the controls treated in a similar manner. To our knowledge, this is the first report of powdery mildew on parsley in Florida, even though parsley has been grown in the area for at least six decades. Noted as being somewhat unique among fungal pathogens because it favors dry rather than moist climatic conditions, it is probably no coincidence that powdery mildew was observed both years during the month of April, the height of Florida's dry season. The fact that monthly rainfall totals of 22 and 35 mm were recorded during April of 2004 and 2005, respectfully, well below the historical average of 72 mm, may have been a contributing influence. Glawe et al. (1), in issuing a first report of E. heraclei on carrots and parsley in the state of Washington and observing ascocarps on carrot tissue, mentioned the prospect of contaminated seed serving as a potential source of dissemination. Although they did not observe the teleomorph on parsley, prospects for its occurrence seem likely. With the bulk of parsley seed planted in Florida being produced in Washington, Oregon, or California, the observations reported herein may provide credence to such a hypothesis. References: (1) D. A. Glawe et al. Online publication. doi:10.1094/PHP-2005-0114-01-HN. Plant Health Progress, 2005. (2) S. T. Koike and G. S. Saenz. Plant Dis. 78:1219, 1994.

First Report of Powdery Mildew of Stachys byzantina (Lamb's Ear) Caused by Neoerysiphe galeopsidis in North America

2007 ◽  
Vol 8 (1) ◽  
pp. 36 ◽  
Author(s):  
Dean A. Glawe ◽  
Steven T. Koike
Keyword(s):  
North America ◽  
Powdery Mildew ◽  
Ornamental Plant ◽  
Commercial Building ◽  
First Report ◽  
Powdery Mildew Disease

During the summer of 2007 the authors encountered a previously unrecorded powdery mildew disease on several plants of the perennial ornamental plant Stachys byzantina K. Koch ex Scheele (common names: woolly hedgenettle, woolly betony, and lamb's ear) growing in a plant bed near a commercial building in Salinas (Monterey Co.), California. This report documents the occurrence of Neoerysiphe galeopsidis on this host in North America. Accepted for publication 11 October 2007. Published 17 December 2007.

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