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A powdery mildew disease of variegated ivy (Hedera canariensis L. var. azorica) was observed on the Tyrrhenian coast in Tuscany (Italy) in spring 1998. Symptoms began as small, nearly circular reddish spots that later enlarged and coalesced. The hyaline mycelium produced abundant, ellipsoid conidia in long chains that ranged from 20 to 40 μm in length and from 12 to 25 μm in width. Cleistothecia were globose (100 to 120 μm diameter), dark brown (when mature) with a basal ring of mycelioid appendages, and contained several (up to 20) ovate asci, each generally containing two ascospores. Ascospores were hyaline, one-celled, ellipsoid (20 to 35 μm in length and 10 to 20 μm in width). The morphological characteristics of this fungus were those given for Erysiphe cichoracearum DC. Infection also was found on English ivy (Hedera helix L.). It is reported that this species is, occasionally, subject to powdery mildew caused by E. cichoracearum (1). Conidia from infected leaves were shaken onto leaves of melon (Cucumis melo L.), cucumber (Cucumis sativus L.), watermelon (Citrullus lanatus [Thunb.] Matsum. & Nakai), lettuce (Lactuca sativa L.), tomato (Lycopersicon esculentum Mill.), tobacco (Nicotiana tabacum L.) and variegated and English ivy. After 7 days, the disease was observed on cucumber, melon, watermelon, tobacco, and variegated ivy. Examination confirmed that test plants were infected with E. cichoracearum. This is the first report of E. cichoracearum on variegated ivy in Italy. Reference: (1) P. P. Pirone. 1970. Diseases and Pests of Ornamental Plants. The Ronald Press, New York.

In 1995, powdery mildew was observed on commercial greenhousegrown Aster ericoides L. from La Plata, Buenos Aires Province. The disease affected about 95% of the growers. Mildew first appeared as white circular patches on the adaxial surface of leaves. As disease progressed, the abaxial surface of leaves, petioles, stems, and calyces were covered by cottony masses of mycelium and conidia, and basal leaves later wilted and died. Young plants (4 to 5 leaves) through flowering plants were affected. Conidia were ovoid-cylindrical, often slightly constricted at the ends, and were produced in chains on unbranched conidiophores. Conidia lacked fibrosin bodies and ranged from 30 to 41 μm × 10 to 19 μm. Long unbranched germ tubes were formed from the ends of conidia. The morphological characteristics of the fungus fit those described for Erysiphe cichoracearum DC (1). In addition, the perfect stage was found on older tissues. Subglobose, dark brown cleistothecia (105 to 210 μm in diameter) with a basal ring of myceloid appendages were observed. Cleistothecia contained multiple ellipsoid asci (48 to 69 μm × 30 to 37 μm) with two hyaline, one-celled, ellipsoid ascospores (22 to 26 μm × 11 to 15 μm). Pathogenicity was tested by pressing diseased leaves onto healthy leaves of aster cv. Sunset and incubating plants in humidity chambers for 48 h. The powdery mildew that developed was morphologically identical to the original isolate. This is the first report of E. cichoracearum on heath aster in Argentina. Reference: (1) H. J. Boesewinkel. Bot. Rev. 46:167, 1980.

Creeping or Canada thistle (Cirsium arvense (L.) Scop.) is a perennial weed of Eurasian origin that arrived in North America as early as the 1700s (3). Spreading by seeds and rhizomes, it is now widely distributed in Canada, Alaska, and 40 other states. It is apparently absent from Texas, Oklahoma, Louisiana, Mississippi, Alabama, Georgia, Florida, and South Carolina (1). Powdery mildew is common on C. arvense in Europe, but it has never been observed in North America (4). In Europe and Asia, powdery mildew of C. arvense is caused by any one of the following fungi: Leveillula taurica, two species of Sphaerotheca, and varieties of Erysiphe cichoracearum and E. mayorii. Specimens of C. arvense infected with powdery mildew (deposited in the U.S. National Fungus Collections as BPI 843471) were collected in the fall of 2003 near Moscow, ID and in two areas in Oregon (the canyon of the Grande Ronde River and near the base of the Wallowa Mountains). Mycelium and cleistothecia were observed on stems and upper and lower surfaces of leaves. The mean diameter of the cleistothecia was 122 (±11.6) μm. Basally inserted, mycelioid appendages were hyaline or brown and varied considerably in length, but most were in the range of 80 to 120 μm. Asci averaged 58 (±5.5) μm × 35 (±4.1) μm in length and width, respectively. Each ascus bore two ascospores averaging 23 (±1.4) μm × 14 (±1.7) μm. Conidia averaged 30 (±3.0) μm × 14 (±0.8) μm. The specimens fit the description of E. cichoracearum DC. (2). Because the length/breadth ratio of conidia is greater than 2, the specimens could be further diagnosed as E. cichoracearum var. cichoracearum (2). Also noteworthy was the presence of the hyperparasitic Ampelomyces quisqualis Ces. ex Schlechtend. E. cichoracearum is thought to be a cosmopolitan powdery mildew of broad host range, but this concept is difficult to reconcile with the absence of mildew on North American populations of C. arvense for more than 200 years. References: (1) Anonymous. USDA Natural Resources Conservation Service Plants Profile for Cirsium arvense. On-line publication, 2003. (2) U. Braun. A monograph of the Erysiphales (powdery mildews), J. Cramer, Berlin-Stuttgart, 1987. (3) G. Cox. Alien Species in North America and Hawaii, Island Press, Washington, D.C., 1999. (4) D. F. Farr et al. Fungal Databases, Systematic Botany and Mycology Laboratory, ARS, USDA. On-line publication, 2003.

In October 2003, potato plants in three fields (cv. Desiree, Satina, Midas, and Mondial) in Lancaster, California exhibited symptoms and signs of powdery mildew. Disease symptoms were most severe on cvs. Desiree and Santina. Disease expression was greater along sprinkler lines and in localized areas from which the disease spread to surrounding plants. Severely affected plants began collapsing just prior to water cutoff. Early symptoms comprise small dark areas on the adaxial surface of leaves, along the veins, and at the petioles. Dark lesions consisting of mycelia and conidiophores were also visible on the main stems of affected plants. As the disease progressed, leaves were covered by a gray powdery fungal mass, and older leaves became necrotic. Conidial chains arising from the hyaline, epiphytic mycelia consisted of two to eight conidia. The cylindric to doliform conidia measured 16.8 to 22.8 μm wide (mean = 19.2, standard error = 0.36, N = 30) × 28.8 to 45.6 μm long (mean = 32.4, standard error = 0.75, N = 30). No cleistothecia were observed. Identification of the causal agent as Golovinomyces cichoracearum (synonyms G. orontii and Erysiphe cichoracearum) based on morphology was confirmed by internal transcribed spacer (ITS)-polymerase chain reaction (PCR). Conidia were washed off the affected leaves, concentrated by filtration and centrifugation, and sonicated to release genomic DNA. PCR was performed on the sonicated conidia with primers ITS4 and ITS5 (2), and the resulting amplicon was purified and sequenced. BLAST analysis of the ITS sequence revealed a 99% homology to E. cichoracearum from an Ambrosia sp. (GenBank Accession No. AF011292). Pathogenicity was confirmed on potato seedlings cv. Red La Soda. Inoculations were performed twice on six plants (three pots) each time. A sterile brush was used to transfer conidia from the affected leaves to seedlings consisting of two to three fully expanded leaves. A plastic bag was placed around each pot containing two seedlings for 1 to 2 days and then removed. Noninoculated controls were stroked with a sterile brush, placed in a plastic bag for 1 to 2 days, and kept in the greenhouse on a separate bench. Two control plants were included for each inoculation. Plants were maintained in a greenhouse at approximately 25 to 28°C and 40 to 60% relative humidity. After 7 days, dark spots were visible on the leaves of all inoculated plants, and conidiophores with conidia identical to those of the isolate used as the inoculum source were apparent after 10 days. The controls showed no disease symptoms or signs. To our knowledge, this is the first report of powdery mildew caused by G. cichoracearum on potato in California. The first field report of the disease was from Washington in 1950 (1), with subsequent reports from Utah and Ohio. References: (1) J. D. Menzies. Plant Dis. Rep. 34:140, 1950. (2) T. J. White et al. PCR Protocols. Academic Press, New York, 1990.

Common sage, Salvia officinalis L., is produced primarily in greenhouses for the culinary herb market in Argentina. Since 2003 during autumn and winter, powdery mildew symptoms have been repeatedly observed on potted common sage plants in commercial greenhouses located on the outskirts of Buenos Aires. The average disease incidence during this period was 85 to 90%. Circular, white, powdery patches developed on leaf surfaces and stems. Heavily infected leaves turned brown and died. Hyaline mycelium and nonlobed appressoria were observed. Conidiophores were simple with straight foot cells measuring 53.0 to 80.0 × 10.0 to 12.3 μm. Conidia were aseptate, hyaline, cylindrical to ovoid, measured 33.0 to 40.5 × 15.0 to 18.5 μm, did not contain fibrosine bodies, and were produced in chains. Cleistothecia were not observed. The pathogen was identified as Erysiphe cichoracearum DC (1). Pathogenicity was confirmed by gently pressing leaves displaying abundant sporulation onto the adaxial surface of healthy leaves. After 10 to 12 days, typical signs and symptoms of powdery mildew appeared on all inoculated plants. Pathogenicity tests were conducted in a greenhouse at 20 to 23°C and included 10 sage plants (five inoculated and five noninoculated). The experiment was performed twice, each time with the same result. Control plants did not show any signs or symptoms. E. cichoracearum DC was previously reported in the United States on Salvia sp. (2).To our knowledge, this is the first report of an outbreak of powdery mildew caused by E. cichoracearun on potted common sage plants produced in greenhouses in Argentina. References: (1) H. J. Boesewinkel. Rev. Mycol. Tome 41:493, 1977. (2) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN, 1989.

During July 2011, a severe powdery mildew outbreak was recorded in pumpkin (Cucurbita moschata Duch.) fields in economically poor areas in the Neelum Valley (Leswa, Mir Pura, Jura, Kundal Shahi, and Bela). Disease symptoms included grayish white circular to irregular patches consisting of epiphytic mycelia and conidia on both surfaces of the leaves of infected vines. Fungal mycelia and conidiophores were also visible in white powdery patches on the main stems, leaves, and petioles of affected plants. Leaves became necrotic with age. Powdery mildew symptoms were more severe on pumpkin vines located in the shade, and severely affected vines collapsed. A voucher specimen (IR00027) has been deposited in First Fungal Culture Bank of the Pakistan (FCBP), Institute of Agriculture Sciences, University of the Punjab, Lahore, Pakistan. For morphological observation, a clear tape strip was used to remove fungal tissue from infected leaves. The tape was mounted on microscope slides with water and examined with a light microscope (2). Conidiophores were unbranched, cylindrical, erect and arose singly on hyphal cells, 110 to 200 × 6 to 12 μm, composed of a foot cell and three to eight barrel-shaped conidia formed in chains with a sinuate edge, followed with a basal septum at the branching point or slightly displaced from the mycelium. Foot cells were 50 to 80 × 6 to 12 μm, and slightly swollen with constriction at the base. Conidia were cylindrical to doliiform, 30 to 50 × 14 to 20 μm and produced in chains. The length/breadth ratio of the conidia was 1.8 to 2.6. Fibrosin bodies were absent in both conidiophores and conidia. No cleistothecia were observed. Identification of the causal agent as Golovinomyces cichoracearum (DC.) V.P. Heluta (synonym Erysiphe cichoracearum) was based on morphology (1). Pathogenicity was determined using field-infected plant leaves transported to a greenhouse. Fresh conidia of field isolates of G. cichoracearum were transferred by a sterile brush from the affected leaves to fully expanded four to five healthy leaves of three 40-day-old vines. For the control, three vines were stroked with a clean sterile brush and control plants were placed 100 m away from the inoculated plants. For disease development 20°C and 80% relative humidity was maintained in the greenhouse. A plastic sheet was placed around each vine for a week and removed later. Inoculated vines developed visible white spots of powdery mildew on the leaves after 10 days in the greenhouse, whereas control plants remained asymptomatic. Fungal colony and conidial morphology on the leaves of inoculated plants were as described above. Previously, G. cichoracearum has been reported on other cucurbits (3) in the plains of Pakistan. To our knowledge, this is the first report of occurrence of G. cichoracearum as a causal agent of powdery mildew on pumpkin in Neelum Valley, Azad Kashmir. References: (1) U. Braun. Beih. Nova Hedwigia 89:1, 1987. (2) J. C. Correll et al. Plant Dis. 71:248, 1987. (3) A. Wahid et al. Pak. J. Agric. Res. 9:209, 1988.

Cocklebur (Xanthium strumarium L., Asteraceae) is an annual broadleaf weed native to the Americas and eastern Asia. The plant is known as one of the worst competitive weeds in soybean fields and also is known to have some phytopharmacological or toxicological properties. In October 2011, a powdery mildew disease was observed on cocklebur growing in a natural landscape at Geomun Oreum located in Jeju Island, South Korea. Initial signs appeared as thin white colonies, which subsequently developed abundant growth on adaxial leaf surfaces. As the disease progressed, brown discoloration extended down infected leaves which withered. Conidia were formed singly and terminally on conidiophores. Primary conidia (20.3 to 28.6 [average 25.1] μm long × 11.1 to 15.2 [14.3] μm wide, n = 30) were ellipsoid with a round apex and truncate base. Conidiophores were straight or slightly curved and 60.1 to 101.7 (97.3) μm long × 8.2 to 13.2 (11.3) μm wide. Chasmothecia were not observed. No fibrosin bodies were observed in the conidia. Morphological characteristics were consistent with descriptions of Podosphaera xanthii (syn. P. fusca) (2,4). To confirm the identity of the causal fungus, the internal transcribed spacer (ITS) region inclusive of 5.8S and 28S rDNA was amplified from white patches consisting of mycelia and conidia on one leaf using ITS1 (5′-TCCGTAGGTGAACCTGCGG-3′) and LR5F (5′-GCTATCCTGAGGGAAAC-3′), and LROR (5′-ACCCGCTGAACTTAAGC-3′) and LR5F primer sets, respectively. The resulting sequences were deposited in GenBank (Accession Nos. JX502022 and JX964999). A NCBI BLASTn search revealed that the rDNA ITS (JX502022) and 28S (JX964999) homologies of isolate EML-XSPW1 represented 99.6% (512/514) and 100% (803/803) identity values with those of P. xanthii (AB040330 and AB462792, respectively). The rDNA ITS and 28S sequence analysis revealed that the causal fungus clustered with P. xanthii (syn. P. fusca), falling into the Xanthii/Fusca phylogenetic group (2,4). Pathogenicity was confirmed through inoculations made by gently pressing infected leaves onto mature leaves of healthy cocklebur plants in the field in August. The six inoculated leaves were sealed in sterilized vinyl bags to maintain humid conditions for 2 days. Seven days after inoculation, symptoms similar to those observed under natural infection were observed on the inoculated plant leaves. No symptoms developed on the uninoculated control plants. A fungal pathogen that was morphologically identical to the fungus originally observed on diseased plants was also observed on inoculated plants. Erysiphe cichoracearum, E. communis, Oidium asteris-punicei, O. xanthimi, P. xanthii, and P. fuliginea have all been reported to cause powdery mildew on cocklebur (1). P. xanthii was first reported on X. strumarium in Russia (3). To our knowledge, this is the first report of powdery mildew on cocklebur caused by P. xanthii in Korea. The powdery mildew pathogen may represent an option for biocontrol of the noxious weed in the near future. References: (1) D. F. Farr and A. Y. Rossman. Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases , December 11, 2012. (2) H. B. Lee. J. Microbiol. 51:1075, 2012. (3) V. A. Rusanov and T. S. Bulgakov. Mikol. Fitopatol. 42:314, 2008. (4) S. Takamatsu et al. Persoonia 24:38, 2010.

Sonchus asper is an exotic annual herb belonging to the Asteraceae family. Crude extracts of S. asper leaves have antiphlogistic and antibacterial properties. In May 2011, severe infection of powdery mildew was observed on S. asper in Henan Province, a central area of China. Symptoms began as small, nearly circular white spots that later enlarged and coalesced. As the disease progressed, white mycelia covered the entire plant, including the inflorescence. The voucher specimens are kept at the Key Laboratory of Plant-Microbe Interaction, Shangqiu Normal University. Conidiophores were erect, 108 to 220 × 10 to 12 μm, and composed of a cylindrical foot cell followed by two to three short cells. Nipple-shaped appressoria were formed on ectophytic mycelia. Conidia were hyaline and cylindrical, without distinct fibrosin bodies, and ranging from 29 to 42 × 19 to 24 μm. Long, unbranched germ tubes were formed from the ends of the conidia. These morphological characteristics suggested that the powdery mildew fungus is the anamorph of Golovinomyces cichoracearum (1,2). Chasmothecia were not observed in the collected samples. To confirm the identification, the internal transcribed spacer (ITS) region of the rDNA was amplified with ITS1 and ITS4 primers (4) and sequenced. The ITS sequence obtained was assigned Accession No. JQ010848 in GenBank, and had 99% similarity to two ITS sequences from different G. cichoracearum accessions (HM449077 and AY739111). The ITS sequence analysis further verified that the causal agent of the powdery mildew on S. asper was G. cichoracearum. Pathogenicity was confirmed by inoculating five healthy plants of S. asper with a conidial suspension (105 conidia/ml) from the infected plants, with five noninoculated plants serving as control. Inoculated plants developed the original powdery mildew symptoms after 10 days, whereas control plants remained healthy. G. cichoracearum (synonym Erysiphe cichoracearum) is a cosmopolitan powdery mildew fungus, parasitic on numerous plant species in the Asteraceae family. It was reported to be infecting S. asper in Bulgaria (3). To our knowledge, this is the first report of G. cichoracearum infections on S. asper in China. S. asper is one of the most important Chinese herbal medicines. The sudden appearance of powdery mildew caused by G. cichoracearum on this plant could result in substantial production loss of S. asper unless fungicide applications are employed. References: (1) U. Braun. Beih. Nova Hedwigia 89:1, 1987. (2) R. T. A. Cook and U. Braun. Mycol. Res. 113:616, 2009. (3) G. Negrean and C. M. Denchev. Mycologia Balcanica, 2004, 1:63. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, CA, 1990.

Ruth's golden aster (Pityopsis ruthii (Small) Small: Asteraceae) is an endangered, herbaceous perennial that occurs only at a few sites along small reaches of the Hiwassee and Ocoee rivers in Polk County, Tennessee. As part of a planned restoration program, Ruth's golden aster has been micropropagated in vitro and acclimatized to greenhouse conditions. In February 2011, several established plants in a greenhouse in Knoxville, TN exhibited signs and symptoms of powdery mildew including growth of white mycelium and conidiophores on the adaxial surface of leaves and slight curling upward of leaf margins. Mycelium was superficial and nipple-shaped appressoria were present. Mycelia, conidiophores, and conidia were removed from several leaves, mounted in water, and examined microscopically. Cylindrical to ovoid conidia (n = 100) lacking fibrosin bodies were borne in chains and had a mean length of 32.0 μm (19.2 to 38.7 μm) and width of 14.9 μm (6.3 to 21.2 μm). The description and dimension of the conidia agreed well with that provided for Golovinomyces cichoracearum (Erysiphe cichoracearum) reported on Coreopsis spp. (1,3) and Cirsium arvense (creeping thistle) (2). The teleomorph was not observed. Total genomic DNA was extracted from infected leaves, amplified with ITS1 and ITS4 primers for the 18S rRNA subunit (4), and visualized on a 2% ethidium bromide agarose gel. An amplicon of fungal origin, approximately 550 bp and smaller than the approximately 700-bp plant ITS amplicon, was excised, purified, and then sequenced. This sequence was deposited in GenBank (Accession No. JF779687) and was 99% identical to two G. cichoracearum accessions (Nos. AB77627 and AB77625). Infected leaves were rubbed on leaves of four healthy plants and healthy leaves were rubbed onto other healthy leaves of two additional plants as controls in the greenhouse. Signs of powdery mildew developed on those plants inoculated with infected leaves after 7 to 10 days and the morphology of the fungus was identical to our previous description. To our knowledge, this is the first report of G. cichoracearum (E. cichoracearum) infecting Ruth's golden aster. We are not aware of the disease occurring in wild populations of the plant, but it does impact the production of micropropagated plants in the greenhouse. References: (1) D. A. Glawe et al. Online publication. doi:10.1094/PHP-2006-0405-01-BR. Plant Health Progress, 2006. (2) G. Newcombe and C. Nischwitz. Plant Dis. 88:312, 2004. (3) T. E. Seijo et al. Online publication. doi: 10.1094/PHP-2006-1214-01-BR. Plant Health Progress, 2006. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press Inc, New York, 1990.

Powdery mildew is an important disease of melons (Cucumis melo L.) cultivated in greenhouses in Brazil. Currently, there are 5 races of Podosphaera xanthii (formerly known as Sphaerotheca fuliginea) and 2 races of Golovinomyces cichoracearum (formerly known as Erysiphe cichoracearum) described on melons worldwide, but only race 1 of P. xanthii has been reported in Brazil (1). However, typical whitish powdery fungal growth was observed on an experimental hybrid yellow melon resistant to race 1 of P. xanthii during the summer of 2000 in a greenhouse in Bragança Paulista, State of São Paulo. Conidia collected from diseased leaves were spread onto 0.5% water agar medium and maintained at 22°C for 24 h with 12 h of light and 12 h of darkness. Most of the germinated conidia displayed fibrosin inclusion bodies when observed in a solution of 3% potassium hydroxide (KOH), and approximately 1 of 50 also displayed forked germ tubes. These features allowed us to identify P. xanthii as the causal agent. Conidia raised on the susceptible yellow melon ‘Amarelo CAC’ were used to inoculate cotyledons of the differential melon lines (2) ‘Hale's Best Jumbo’ (susceptible to races 1, 2, and 3 of P. xanthii), ‘PMR-45’ (resistant to race 1 and susceptible to races 2 and 3), and ‘PMR-6’ (resistant to races 1 and 2 and susceptible to race 3). Inoculations were performed on 10 plants of each differential line and replicated four times. The presence or absence of symptoms was evaluated 18 days after inoculation. ‘Hale's Best Jumbo’ and ‘PMR-45’ were rated as susceptible while ‘PMR-6’ was rated as resistant, thus indicating the presence of race 2 of P. xanthii in Brazil. During field surveys from 2001 to 2003, this race was found on squash (Cucurbita moschata), summer squash (C. pepo), and melons in São Paulo. References: (1) F. J. B. Reifschneider et al. Plant Dis. 69:1069, 1985. (2) C. E. Thomas et al. Cucurbit Genet. Coop. 7:126, 1984.

Purple coneflowers (Echinacea purpurea) are grown in North America and Europe for their medicinal properties and as ornamental plants. In September 1997 and again in 1998, a previously undescribed disease was noticed on fully grown coneflower plants in Summerland and Oliver, British Columbia. Mycelia were observed on stems, foliage, and flowers, and distinct dark red to black, round (approximately 5 mm in diameter) lesions were observed on the flower petals. The disease appeared similar to powdery mildews that have been reported on numerous genera of the Asteraceae. Samples of the diseased tissue were examined and the salient features of the fungus on two specimens were determined: cleistothecia infrequent, subglobose or flattened on the side next to the leaf surface, 121 to 209 μm in diameter; epidermal (surface) cells 20 μm in diameter; appendages hyphoid, 5 μm in diameter, up to 200 μm long; asci, 10 to 19 in each cleistothecium, broadly ellipsoid, 47 to 85 × 28 to 37 μm with a short stalk, about 8 to 13 μm long and 8 μm in diameter; ascospores, immature, two per ascus, ellipsoid to broadly ellipsoid, 17 to 25 × 11 to 13 μm, thin walled, hyaline, and smooth; conidia oblong with sides slightly convex and apices truncate, 27 to 40 × 14 to 20 μm, walls hyaline, thin, smooth. Based on the occurrence of asci that contained two ascospores and the hyphoid appendages on the cleistothecia we concluded that the fungus was Erysiphe cichoracearum DC. Damage due to this disease was minimal in 1997 and 1998 because it developed very late in the growing season and occurred sporadically within the plantings. In order to complete Koch's postulates, Echinacea purpurea plants grown in the greenhouse were inoculated with a conidial suspension (105 to 106 conidia per ml) from field-infected plants. Powdery mildew first appeared 3 months later, eventually infecting leaves and stems of 12 of 49 inoculated plants. It was distinctly white and in discrete patches on leaves, compared with coalescing dark brown areas on the stems. Microscopic examination of the conidia confirmed that they were E. cichoracearum. Although powdery mildew caused by E. cichoracearum has been widely reported on lettuce, safflower, and other cultivated and wild Compositae, we found no reference to it on Echinacea spp. in Canada (1,2), the U.S. (3), or elsewhere in the world (4). The specimens have been deposited in the National Mycological Herbarium of Canada (DAOM) with accession numbers 225933 and 225934 for Oliver and Summerland, B.C., respectively. References: (1) U. Braun. Beih. Nova Hedwigia 89:1, 1987. (2) I. L. Conners. 1967. An annotated index of plant diseases in Canada and fungi recorded on plants in Alaska, Canada, and Greenland. Canada Dept. of Agric. Pub. 1251. (3) D. F. Farr et al. 1989. Fungi on Plants and Plant Products in the United States. American Phytopathological Society, St. Paul, MN. (4) J. Ginns. 1986. Compendium of plant disease and decay fungi in Canada, 1960-1980. Agriculture Canada Pub. 1813.

International audience; In a survey of cucurbit crops in Sudan, 234 samples of melon, cucumber, and squash showing symptoms of powdery mildew were infected with Sphaerotheca fuliginea, while Erysiphe cichor-acearum was only observed on two samples of watermelon showing mild symptoms. Ieeveillula taurica was not observed on any sample. Field trials with differential lines of melon revealed the presence of race 1 of S. fuliginea in Gezira (Central Sudan) in the summer of 1993, and race 2 in the following winter. Virulence tests in controlled conditions on a limited number of isolates suggest that a shift in prevalence of those races may have occurred on that site over time. The geographic scale of this shift was probably limited as race 0 was observed in late autumn in northeast Sudan in the Gash Delta.

Thirty-six commercial and plant-introduction genotypes of Jerusalem artichoke (Helianthus tuberosus) were grown near Athens, Georgia, to determine their reactions to Puccinia helianthi, Coleosporium helianthi, and Erysiphe cichoracearum. Tuber characteristics and yields were also determined. The genotypes varied from highly susceptible to highly resistant to each of the three pathogens. Generally, genotypes that were highly susceptible to P. helianthi were mostly resistant to C. helianthi. The reverse was also true. The genotypes that had the largest and most desirable tubers and the inherent potential for high-tuber yield were often the most susceptible to P. helianthi (.)