Leaf Spot of Arugula, Caused by Alternaria japonica, in California.

Arugula (Eruca vesicaria subsp. sativa (Mill.) Thell. is a Cruciferous plant used for culinary purposes. From 2012 to 2013, a foliar disease seriously impacted the growth and quality of about 0.1 ha of hydroponically grown arugula at a Santa Barbara County nursery. Samples of affected arugula seedlings exhibited adaxial and abaxial symptoms of mottling with circular to oval, water soaked, dark green leaf spots, each 1 to 3 mm in diameter, and some of which coalesced. Conidia of an Alternaria sp. were observed on the foliage. Symptomatic leaf pieces were disinfested with 0.6% NaOCl, blotted dry, and plated on acidified potato dextrose agar (APDA). Cultures were incubated under near-UV lights for 24 h/day. Olivaceous-grey colonies of the same Alternaria species observed on the leaves grew after 7 days. After 21 days on carrot-piece agar (3), the fungus produced beakless conidia with longitudinal and constricted transverse septa that measured 30.0 to 69.0 × 12.5 to 20.0 µm and were borne singly or in short chains of 2 to 3 conidia. In addition, knots of dark, thick-walled micro-chlamydospores were produced by the hyphae. The fungus was identified morphologically as Alternaria japonica Yoshii (2), and the species confirmed by sequence analysis. A portion of the internal transcribed spacer (ITS) region of ribosomal DNA (rDNA) was amplified using ITS1 and ITS4 primers (4). The sequence (GenBank Accession No. KJ126846) was 100% identical to the ITS rDNA sequence of an isolate of A. japonica (KC584201) using a BLASTn query. A. japonica was also detected in seeds of the lot used to grow the affected arugula crop. Pathogenicity of a single isolate was tested by inoculating four 37-day-old plants each of arugula, cabbage (Brassica oleracea L. var. capitata), and broccoli (B. oleracea L. var. botrytis L.). Inoculum was obtained from 11-day-old cultures of the isolate grown at 24°C on half-strength APDA. Half of a 2.5 cm diameter agar plug containing hyphae and conidia was ground in 2 ml of sterilized water, and the volume of water increased to 45 ml. Leaves of four plants/host species were sprayed with 3.5 to 4.0 ml of inoculum. The inoculated plants and four control plants of each species treated similarly with sterilized water were immediately incubated in a dark dew chamber at 23°C. After 72 h in the dew chamber, inoculated plants of all three hosts produced similar symptoms of wilting, water soaking, and dark green leaf spotting as the original symptomatic field plants. Conidia formed in the leaf spots on both sides of inoculated leaves. A. japonica was re-isolated from all of the inoculated plants but from none of the symptomless control plants using the method previously described. Pathogenicity tests were repeated, with similar results. Although reported in Italy in 2013 (1), to our knowledge, this is the first report of A. japonica on arugula in the United States. References: (1) G. Gilardi et al. Acta Hort. 1005:569, 2013. (2) E. G. Simmons. Page 368 in: Alternaria, An Identification Manual. CBS Fungal Biodiversity Centre, Utrecht, 2007. (3) S. Werres et al. Z. Planzenkr. Pflanzensh. 108:113, 2001. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.

First Detection of Puccinia ballotiflora on Salvia greggii.

Salvia greggii, autumn sage, is grown for its bright red to white flowers that bloom in late summer and fall. In February of 2008, a rust sample was sent to the CDFA plant pathology diagnostics laboratory in Sacramento from a nursery in Santa Barbara County, CA. Pustules were abundant on older leaves causing moderate defoliation of containerized stock. Only the varieties with entirely red or pink flowers were affected. S. greggii 'Hotlips,' a popular white/red bicolor, was unaffected. Amphigenous uredinia were cinnamon brown, round, powdery, and sometimes surrounded by yellow halos. Pustules were found primarily on the leaves, although a few were on the stems. Urediniospores were broadly obovoid, subglobose to broadly ellipsoid, echinulate, and 22 to 27 × 24 to 32 µm (24.9 × 26.9 µm average) with one apical pore and 2 to 3 equatorial pores. Urediniospore walls were cinnamon brown in color and measured 1.0 to 2.0 µm (1.5 µm average). No telia were observed. After the initial detection, this rust was found in additional nursery sites in Santa Cruz, Santa Clara, Santa Barbara, and Ventura counties in 2008 and 2009. In November of 2011, a sample from a landscape planting in Santa Barbara County of a similar rust with telia and teliospores was submitted. Urediniospores and teliospores were present in the same lesions. Lesions with teliospores were located primarily on the stems. Mature teliospores were two-celled, verrucose, chocolate brown, and 25 to 31 × 32 to 40 µm (28.6 × 35.3 µm average) with a pedicel ranging from 8 to 12 × 38 to 104 µm, sometimes attached obliquely. The rust matched the morphological characteristics of Puccinia ballotiflora (Syn = P. ballotaeflora Long) (2). To confirm pathogenicity, three 20-cm-tall plants of S. greggii 'Navajo Red' in 3.8-liter pots were spray inoculated with 10 ml of a 2.5 × 103 urediniospores per ml suspension and incubated in a dew chamber at 23°C for 2 days in the dark. Plants were transferred to a growth chamber maintained at 22°C with a 12-h photoperiod. Three plants were sprayed with sterile distilled water as controls. Uredinial pustules (1 to 2 mm) appeared on the abaxial surface of the leaves after 3 weeks. The pathogenicity test was repeated with similar results. The internal transcribed spacer region of rDNA and a portion of the 28S rDNA were amplified with primer pairs ITS5 (5'-GGAAGTAAAAGTCGTAACAAGG-3'), Rust1 (5'-GCTTACTGCCTTCCTCAATC-3'), and Rust2inv (5'-GATGAAGAACACAGTGAAA-3'), LR6 (5'-CGCAGTTCTGCTTACC-3') as described by Aime (1) and sequenced using the amplification primers, Rust2 (5'-TTTCACTGTGTTCTTCATC-3') and Rust3 (5'-GAATCTTTGAACGCACCTTG-3'). BLAST query of the assembled sequence, GenBank KF381491, was 91% identical to P. acroptili, JN204194, its closest match of similar length. P. ballotiflora has been found in Colombia on S. cataractarum, S. petiolaris, and S. mayori (3), and in Texas and Mexico on S. ballotiflora (4). To the best of our knowledge, this is the first detection of P. ballotiflora on S. greggii worldwide. P. ballotiflora is already widespread in the nursery trade in California and frequent fungicide applications are necessary to keep plants marketable. References: (1) M. C. Aime. Mycoscience 47:112, 2006. (2) J. W. Baxter and G. B. Cummins. Lloydia 14:201, 1951. (3) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Botany and Mycology Laboratory, Online publication http://nt.ars-grin.gov/fungaldatabases ARS, USDA, 2014 (4) F. D. Kern et al. Mycologia 25:448, 1933.

First Published Report of Rust on White Alder Caused by Melampsoridium hiratsukanum in the United States.

White alder (Alnus rhombifolia) is a fast-growing tree native to the western United States and is planted frequently in landscapes. In September 2010, mature leaves of white alder with small, orange-yellow pustules were collected in a commercial nursery in Santa Cruz County, CA. Approximately 25 white alder trees were affected. Collected leaves were sent to the California Department of Food and Agriculture Plant Pest Diagnostics Laboratory. Young uredinial pustules were bullate, with urediniospores emerging from a single pore in the pustule. Spiny cells lined the ostiole. With age, pustules broke open to release more spores. Urediniospores were obovate to oval and measured from 14 to 20 × 27 to 41 µm (17.1 × 32.2 µm average, n = 62). Spores were uniformly echinulate and contained a nearly hyaline cell wall measuring from 1 to 2 µm (1.5 µm average) in thickness. A portion of the 28S ribosomal subunit (GenBank Accession No. KC313888) and the internal transcribed spacer regions (KC313889) were amplified and sequenced from DNA extracted from urediniospores using primers LR6 and rust2inv (1) and ITS1-F and ITS4-B (2), respectively. Our ITS sequence had 99% identity to GenBank accession EF564164, Melampsoridium hiratsukanum. In September 2011, white alder leaves with similar symptoms were collected from a commercial nursery in Santa Barbara County, CA. The spore morphology matched the white alder sample previously collected in Santa Cruz County, CA, in 2010. At that time, pathogenicity assays were conducted on three 1-year-old, 61-cm white alder trees planted in 3.8-liter pots. Six detached leaves with visible rust pustules were rubbed gently onto both the apical and distal side of moistened leaves of the healthy alders. Each infected leaf was used to inoculate a total of 6 to 10 healthy leaves by rubbing two leaves per tree before moving to the next tree. Leaves on three additional white alder trees were rubbed with healthy leaves as controls. Trees were incubated in a dew chamber for 3 days in darkness at 24°C, then placed in a growth chamber at 22°C with a 12-h photoperiod. Twelve days after inoculation, small lesions were visible on a few of the leaf undersides of each inoculated tree. Not all inoculated leaves developed pustules. No lesions developed on the control trees. M. hiratsukanum has been reported in Canada, Europe, and eastern Asia (3). There are no published reports of this rust in the United States, but there is an unpublished specimen from white alder in the USDA Systematic Mycology Herbarium (BPI 028048) collected from California in 1931, which was identified as M. hiratsukanum by G. B. Cummins using morphological criteria. We are unaware if older specimens of this rust exist because we were unable to search other herbaria in the United States. To the best of our knowledge, this rust has been present in California since 1931, but has only recently been found causing disease in nursery plants. There have been no reports of the serious foliar disease symptoms on trees in California wild lands as have been reported in Europe, presumably due to dry summer and fall seasons in white alder's natural habitat. References: (1) M. C. Aime. Mycoscience 47:112, 2006. (2) M. Gardes and T. D. Bruns. Mol. Ecol. 2:113, 1993. (3) J. Hatula et al. Mycologia 101:622, 2009.

First Report of Fusarium Wilt Caused by Fusarium oxysporum f. sp. passiflorae on Passion Fruit in North America.

Passiflora edulis Sims f. edulis, known as purple passion fruit, is a woody, perennial vine that is grown for its attractive two-part flower and its purple, edible fruit (4). In November 2009, passion fruit vines were collected during a regulatory nursery inspection in Santa Barbara County and submitted to the California Department of Food and Agriculture Plant Pest Diagnostics Laboratory. Nearly 100% of the plants inspected, all of which were approximately 1.25 m tall, appeared stunted, defoliated, and severely wilted. Dark brown vascular discoloration was present in the roots and lower stems of the plants. A pinkish violet Fusarium oxysporum colony containing chlamydospores, multiseptate macroconidia, and microconidia formed on monophialidic conidiophores was consistently isolated from roots and stems onto half-strength acidified potato dextrose agar (aPDA). All further experiments were done with an isolate obtained from a single conidium. A portion of the translation elongation factor gene (TEF-1α) was amplified and sequenced with primers ef1 and ef2 from our isolate (GenBank No. JF332039) (3). BLAST analysis of the 615-bp amplicon with the FUSARIUM-ID database showed 99% similarity with a F. oxysporum passion fruit isolate from Australia (NRRL 38273) (3). To confirm pathogenicity, washed roots of four-leaf stage seedlings approximately 10 cm tall were submerged in a conidial spore suspension (106 spores/ml) for 15 min. The conidial suspension was prepared by flooding 10-day-old cultures grown on aPDA medium with sterile distilled water. Seven seedlings were inoculated and planted in 10-cm2 pots and kept in a 25°C growth chamber with a 12-h photoperiod. Seven seedlings were mock inoculated with sterile water. After 3 weeks, four of the seven inoculated plants had leaves with yellow veins and discolored roots and had partially defoliated. Two of the four symptomatic plants also had brown stem cankers. F. oxysporum grew from the isolated roots and stems of all the inoculated plants. F. oxysporum did not grow from root and stem pieces from the water-dipped plants and the plants remained asymptomatic. Inoculations were repeated on plants approximately 15 cm tall with F. oxysporum growing from roots and stem pieces of all inoculated plants. Symptoms of yellow veins and root necrosis were not observed until 4 weeks after inoculation. Fusarium wilt caused by F. oxysporum f. sp. passiflorae is a significant disease of P. edulis f. edulis in Australia. The disease has also been reported in South Africa, Malaysia, Brazil, Panama, and Venezuela; but it is unclear as to whether the symptoms were caused by Fusarium wilt or Haematonectria canker (1). Banana poka (P. mollissima), P. ligularis, and P. foetida are also susceptible hosts (2). To our knowledge, this is the first report of Fusarium wilt caused by F. oxysporum f. sp. passiflorae on passion fruit in North America. Passion fruit is not commercially produced for consumption in California so the economic importance of this disease appears to be limited to nursery production and ornamental landscapes. The grower of the California nursery stated that the infected passion fruit plants had been propagated on site from seed. The source of inoculum at this nursery remains unknown. References: (1) I. H. Fischer and J. A. M. Rezende. Pest Tech. 2:1, 2008 (2) D. E. Garder. Plant. Dis. 73:476, 1989. (3) D. M. Geiser et al. Eur. J. Plant Pathol. 110:473, 2004. (4) F. W. Martin et al. Econ. Bot. 24:333, 1970.

First Report of Cercospora beticola Causing a Leaf Spot Disease on Acanthus mollis in California.

The genus Acanthus (Acanthaceae) includes ~30 herbaceous, perennial species grown for their attractive foliage and flower spikes. Between June and December 2009 the CDFA Plant Pest Diagnostics Lab in Sacramento, CA received multiple leaf spot disease samples on Acanthus spinosus and A. mollis, commonly known as bear's breeches. Samples were collected four times from two nurseries in Santa Barbara County. Disease was observed in nearly 100% of the plants inspected. Leaf spots were brown, roundish to elliptical, and 1 to 4 mm in diameter. Older spots often developed grayish centers and often coalesced, leading to large necrotic areas. Conidiophores were fasciculate, amphigenous, light brown to olivaceous, multiseptate, geniculate, and had distinctive spore scars. Conidia were hyaline, straight to slightly curved with tapered tips and truncate bases. Conidia were solitary, multiseptate (1 to 10) and 48 to 160 × 2.5 to 5 µm (average 100 × 3.9 µm). Colonies obtained from single conidial isolates were established on acidified potato dextrose agar (APDA). Morphologically, the causal agent was identified as Cercospora diantherae Ellis and Kellerm (1), a species synonymous with C. apii sensu lato (2). The C. apii sensu lato complex includes three morphologically similar taxa, C. apii, C. beticola, and C. apiicola (3). Sequence analysis of the internal transcribed spacer region from the Acanthus isolate confirmed it belongs to the C. apii complex (GenBank HQ328503). Multiplex PCR to distinguish species within the complex was also performed on the isolate (3). A 176-bp fragment was only observed in the PCR reaction containing the C. beticola primers. To confirm pathogenicity, hyphal suspensions were used to inoculate healthy leaves of A. mollis plants potted in 3.7-liter containers. Hyphal suspensions were obtained by grinding 3-week-old colonies grown on APDA with distilled water using a mortar and pestle. Both sides of healthy leaves and petioles were sprayed with ~40 ml of the suspension. Five plants were inoculated with C. beticola and five plants were sprayed with sterile water. Plants were incubated in a dew chamber for 48 h and then transferred to a 25°C growth chamber with a 12-h photoperiod. The experiment was repeated. Five days after inoculation, small necrotic leaf spots developed on the leaves. After 14 days, the spots had enlarged and the leaves began to turn yellow. Over time, the spots coalesced leading to large necrotic areas, especially along the leaf margins. Petiole spots, not seen on field samples, were seen on laboratory inoculated plants. Sporulation of C. beticola occurred within most of the spots and the pathogen was successfully reisolated from all inoculated leaves. No foliar symptoms developed on any of the control plants. Worldwide, C. beticola is a destructive pathogen of sugar beet (4), and has also been reported on a number of other plant hosts (3). To our knowledge, this is the first report of C. beticola causing a leaf spot disease on a host in the Acanthaceae family. This strain has been deposited into the culture collection at Centraalbureau voor Schimmelcultures. References: (1) C. Chupp. A Monograph of the Fungus Genus Cercospora. Ithaca, N.Y., 1953. (2) P. W. Crous and U. Braun. Mycosphaerella and Its Anamorphs 1: Names Published in Cercospora and Passalora. CBS, Utrecht, the Netherlands, 2003. (3) M. Groenwald et al. Mycologia 98:275, 2006. (4) W. W. Shane and P. S. Teng. Plant Dis. 76:812, 1992.

First Report of Verticillium Wilt on Field-Grown Cosmos Caused by Verticillium dahliae in California.

Cosmos (Cosmos bipinnatus Cav.) is an annual that is grown for cut flowers or as a landscape bedding plant. In late July 2009, cosmos plants were collected from a 0.4-ha field in Santa Barbara County, CA and submitted to the California Department of Food and Agriculture's Plant Pest Diagnostics Laboratory. Plants showed symptoms of chlorosis, wilting, necrosis, and death. Symptomatic plants comprised approximately 50% of the crop. Roots and stems appeared entirely discolored. Pieces (4 mm3) were taken from the edges of the discolored tissue of roots and stems, surface sterilized in 0.6% NaOCl for 2 min, and placed onto one-half-strength acidified potato dextrose agar (APDA). Fungal colonies consisted of fine, hyaline hyphae with verticillate conidiophores producing hyaline conidia, measuring 4.2 to 7.0 × 1.8 to 3.0 µm (5.13 × 2.44 µm average), in slimy masses. Microsclerotia (30.0 to 137.5 × 15.0 to 60.0 µm, 57.6 × 33.7 µm average) formed after 1 week in culture, causing the center of the colony to darken. Morphological characteristics were consistent with those of Verticillium dahliae (2). The internal transcribed spacer region (ITS) of rDNA was amplified for one isolate from cosmos using ITS1 and ITS4 primers as described by White et al. (3), and the amplicon was sequenced (GenBank Accession No. GU99602). BLAST analysis of the 455-bp amplicon showed 100% identity with the ITS sequence of V. dahliae from cosmos in Italy (GenBank Accession No. GQ130129). Pathogenicity of the California cosmos isolate of V. dahliae was determined by inoculating 10 1-month-old seedlings (each approximately 20 cm high) of C. bipinnatus 'Sensation Mix' with this isolate. Plants were inoculated with spores harvested by flooding 2-week-old cultures of V. dahliae grown on APDA medium with sterile distilled water. Plant root tips were trimmed and submerged in a spore suspension (1.3 × 106 spores/ml) for 5 min. Ten plants were dipped in water as the negative control treatment. Plants were then planted in a commercial potting mix in 10-cm-diameter pots and kept in a growth chamber at 25°C with a 12-h photoperiod. Inoculated plants were chlorotic and wilted when root and stem isolations were performed 1 month after inoculation. V. dahliae grew from stems and roots of 7 and 2 of the 10 inoculated plants, respectively. The inoculation experiment was repeated on six 5-month-old plants with similar results, except V. dahliae was isolated from the roots and stems of six and five plants, respectively. No symptoms developed on plants dipped in water, and Verticillium spp. did not grow from isolated root or stem pieces from the noninoculated plants in either experiment. On the basis of morphological and ITS sequence information, the fungus was identified as V. dahliae. V. dahliae is an economically important pathogen with a wide host range worldwide including cosmos in Italy (1). The affected field in California had a history of vegetable and flower seed crops, as well as vegetables for consumption. Infection of cosmos may have been from soilborne microsclerotia from previous susceptible crops. To our knowledge, this is the first report of Verticillium wilt on cosmos in California. References: (1) A. Carlucci et al. Plant Dis. 93:846, 2009. (2) D. L. Hawksworth and P. W. Talboys. No. 256 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1970. (3) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, 1990.

First Report of Botryotinia Blight of Asiatic Hybrid Lily Caused by Botryotinia sphaerosperma in North America.

In November 2002, a disease was observed on eight cultivars of Asiatic hybrid lilies (Lilium sp.) in two fields in Carpinteria, CA. The same disease was observed on greenhouse grown Asiatic hybrid lilies in Nipomo, CA in an adjacent county. 'Monte Negro' was the most severely affected. Symptoms consisted of necrotic leaf tips as well as 5- to 10-mm ellipsoidal necrotic spots on stems and the abaxial and adaxial leaf surfaces. Lesions were initially dark brown and water soaked, becoming lighter as they dried. Although leaf spot symptoms usually began at the leaf tip, eventually the entire leaf would become blighted. Disease symptoms were not observed on Oriental hybrid lilies in the same nurseries. A Botrytis sp. was consistently associated with the disease symptoms. In pure culture, the fungus matched the description of Botryotinia sphaerosperma (Gregory) Buchw. (anamorph Botrytis sphaerosperma (Gregory) Buchw.) (1). The fungus is distinguished by its large, spherical conidia that average 23 to 25 µm in diameter at maturity. The conidia are born in compact heads on unbranched conidiophores. Conidia and conidiophores are hyaline when young. At maturity, the conidia turn dark brown, whereas the conidiophores turn blackish brown. The fungus formed abundant sclerotia on potato dextrose agar when incubated at room temperature with 12 h per day of fluorescent lighting. The sclerotia were black, ovate to sphaeroidal, had a rough surface, and were 1.5 to 2.5 × 1 to 2.5 mm. Apothecia were not observed. Pathogenicity was tested on 12 Asiatic hybrid and 12 Oriental hybrid lilies. Inoculum consisting of mycelial fragments and conidia (1 × 105 conidia per ml) was produced on lily leaf agar (500 ml of H2O, 7.5 g of agar, and 25 g of healthy, macerated lily leaves). Plants were inoculated by rubbing leaves and stems with the spore and mycelial fragment suspension using cotton swabs. Plants were maintained in a greenhouse at 25°C. After 7 days, characteristic lesions were observed on the leaves and stems of Asiatic hybrid and Oriental hybrid lilies, from which the same Botrytis sp. was consistently isolated. Three control plants each of Asiatic hybrid and Oriental hybrid lilies treated with water as a check, remained symptomless. Although studies to determine potential fungicides for controlling this pathogen have not yet been undertaken, good sanitation, a lily-free period, and steam sterilization of beds should be considered in the management of this disease. In Europe, this fungus has been reported as a pathogen on Lilium regale (2). To our knowledge, this is the first report of this pathogen in North America. Herbarium specimens were submitted to the USDA APHIS mycology laboratory in Beltsville, MD (Accession No. BPI 842231). Cultures were also submitted to the American Type Culture Collection (MYA-2890). References: (1) P. H. Gregory. Trans. Br. Mycol. Soc. 25:26, 1941. (2) G. L. Hennebert. Friesia 9:52, 1969.

First Report of the Rust Miyagia pseudosphaeria on Sonchus oleraceus in the Americas.

In January 2002, a rust was observed on leaves and stems of the weed Sonchus oleraceus L. (annual sowthistle) in Santa Barbara, CA. Infected plants were collected in Santa Barbara and Monterey counties, CA. Specimens were examined microscopically and compared with a published description (1) and herbarium specimens at the USDA National Fungus Collection, Beltsville, Maryland. The fungus was identified as Miyagia pseudosphaeria (Mont.) Jorst. based on characteristics of the uredinia and urediniospores. The uredinial sori were subepidermal, erumpent, and single or in groups. Sori were surrounded by peripheral, laterally connected, chestnut brown paraphyses that initially enclosed the developing urediniospores and eventually opened partially at the apex, breaking the host epidermis and remaining as a wall surrounding the spores. The urediniospores were ellipsoid, ovoid, or pyriform with yellowish, often granular, contents and measured 21.5 to 43 × 17 to 26.5 µm. The urediniospore walls were hyaline and finely echinulate and 2.5 to 3.5 µm thick with germ pores sometimes evident in median view. The paraphyses were 70 to 140 × 6 to 8 µm, thick-walled, hyaline below, chestnut brown above, and often somewhat wider or dichotomously branched at the apex. To test pathogenicity, a spore suspension (4.7 × 104 spores/ml) was sprayed onto 7-week-old annual sowthistle plants. Plants were incubated in a dew chamber for 48 h and maintained in a greenhouse at 22 to 24°C. Signs of rust were observed after 2 weeks, and microscopic examination confirmed that the same fungus was present. Uninoculated control plants did not develop rust. Using the same method, plants of prickly sowthistle (S. asper (L.) Hill) were inoculated and also developed the disease. All inoculation experiments were conducted two times and the results were the same. The rust was found on almost all annual sowthistle plants examined in Santa Barbara County, especially well-nourished specimens growing as weeds in irrigated landscapes, vegetable fields, or in container nurseries. Diseased plants were found in and around vegetable fields in Monterey County. M. pseudosphaeria is macrocyclic, autoecious, and known only on Sonchus spp. It has been reported from northern Africa, China, Europe, Japan, New Zealand, and the former Soviet Union. To our knowledge, this is the first report of M. pseudosphaeria in the Americas. Voucher specimens have been deposited in the U.S. National Fungus Collection (BPI 842025, 842055 to 842060, and 842230). Images can be viewed at nt.ars-grin.gov . References: (1) M. Wilson and D. M. Henderson. British Rust Fungi. Cambridge University Press, Cambridge, 1966.

First Report of Powdery Mildew on Nandina domestica (Berberidaceae) in North America.

Nandina domestica Thunb. (heavenly bamboo) is an ornamental plant that is widely planted in landscapes in California and other states. Since 1996, powdery mildew disease has been seen on outdoor landscape N. domestica in various regions of California (Alameda, Monterey, Riverside, and Santa Barbara counties). Symptoms consist of reddening of leaf and stem tissues colonized by the fungus and curling and twisting of infected leaves. The following observations were the same for all collected isolates. White ectophytic mycelium was observed on leaves and petioles. Mycelium on leaves was amphigenous, mostly epiphyllous, and effused or in patches. Hyphal appressoria were nipple-shaped to lobed and sometimes opposite in orientation. Conidiophores were cylindrical, straight, sometimes slightly flexuous, 22 to 32 × 6 to 8 µm in dimension, and followed by one to two shorter cells. Conidia were cylindrical, produced singly, and 27 to 42 × 11.5 to 14 µm in dimension. Fibrosin bodies were not observed. Conidial germ tubes were approximately twice the length of the spore, originated from the ends of the spore, and terminated in simple appressoria. Cleistothecia were not present. Based on these characteristics, the fungus was identified as Microsphaera berberidis (DC) Lév. (1). Pathogenicity was confirmed by gently pressing diseased leaves on leaves of healthy N. domestica plants. Plants were incubated in a humidity chamber at 22 to 24°C, and after 10 to 14 days, powdery mildew colonies developed. A voucher specimen was deposited in the University of California Herbarium (UC 1738622). Additional inoculation experiments showed that four other N. domestica cultivars were susceptible (Compacta Nana, Gulf Stream, Harbour Dwarf, and Royal Princess). Helfer (2) noted several possible candidates for the Nandina powdery mildew pathogen in the United Kingdom. However, due to the conidial characteristics of that fungus and the paucity of character descriptions for the several species mentioned, no species name was given to the Edinburgh isolate. In contrast, the mitosporic characteristics of our isolates fit the description for M. berberidis. This is the first report of powdery mildew on N. domestica in North America. References: (1) U. Braun. Nova Hedwigia 89:1, 1987. (2) S. Helfer. Plant Dis. 79:424, 1995.

First Occurrence of White Rust of Arugula, Caused by Albugo candida.

In California, arugula (Eruca sativa) is grown commercially as a component of specialty mixed green salads. In 1999, white rust was observed on arugula in the central coast county of Santa Barbara. Symptoms consisted of white, blisterlike sori beneath the raised host epidermis on the underside of leaves from the seedling stage onward. Secondary infection of flower heads led to staghead development. Affected plantings were severely diseased and were not harvested. The pathogen was confirmed to be Albugo candida (Pers.) Kunze (2). Sporangia diameters ranged from 19.5 to 22.2 µm. Inoculum for pathogenicity tests was prepared by scraping sporangia from infected leaves and incubating them in sterile, distilled water for 12 h at 5°C to induce zoospore formation (1). The following plants were then spray inoculated: arugula, cauliflower (Brassica oleracea subsp. botrytis), Chinese cabbage (Brassica campestris subsp. pekinensis), Japanese mustard (Brassica campestris subsp. nipposinica), red mustard (Brassica juncea subsp. rugosa), and tah tsai (Brassica campestris subsp. narinosa). Twelve plants of each species were inoculated with 1.5 × 104 spores per ml at the six- to eight-leaf stage. Plants were incubated in a dew chamber for 48 h at 18°C and then maintained in a greenhouse at 20 to 24°C. After 10 to 12 days, white rust pustules similar to the original symptoms observed in the field developed only on arugula. The experiment was conducted three times and the results were the same. Distinct biological races of A. candida have been described for some Brassicaceae hosts of white rust (1). This is the first report of white rust of arugula in California caused by A. candida. References: (1) R. S. Pidskalny and S. R. Rimmer. Can. J. Plant Pathol. 7:283, 1985. (2) G. S. Pound and P. H. Williams. Phytopathology 53:1146, 1963.

First Report of Black-Foot Disease, Caused by Cylindrocarpon obtusisporum, of Grapevine in California.

Black-foot disease, caused by Cylindrocarpon obtusisporum (Cook & Harkn.) Wollenweb., impacts young table and wine grape (Vitis vinifera) plantings throughout California. Two- to 5-year-old grapevines showed reduced vigor with small-sized trunks, shortened internodes, uneven wood maturity, sparse foliage, and small leaves with interveinal chlorosis and necrosis. In cross-section, trunks showed dark brown to black streaking in a few to most of the vascular elements. Symptoms included a reduction in root biomass and root hairs with sunken, necrotic root lesions. Pith of affected vines was compacted and discolored. Isolations made from roots, vascular elements, and pith tissue consistently yielded colonies of C. obtusisporum as verified by descriptions in standard texts. Koch's postulates were completed by dipping the roots of cv. Carignane seedlings in a 108 spore per ml suspension for 30 min. Plants were repotted in an artificial soil mix and held in a controlled environment facility at 24°C. Typical black-foot symptoms developed on 92% of the plants within 8 weeks. Control plants dipped in distilled water remained healthy. Cylindrocarpon destructans, a species closely related to C. obtusisporum, was first reported to cause "black-foot disease" on young vines in 1961 (2). In 1975, C. obtusisporum was reported to produce similar "black-foot" symptoms (1). We propose the common name Cylindrocarpon black-foot disease be used with both species. References: (1) S. Grasso et al. Vitis 14:36, 1975. (2) D. R. Maluta and P. Larignon. Viticulture 11:71, 1991.

First Report of Three Phaeoacremonium spp. Causing Young Grapevine Decline in California.

A grapevine decline of unknown etiology is currently under investigation in California. Two- to 5-year-old vines show low vigor with undersized trunks, short internodes, uneven wood maturity, sparse foliage, and stunted, chlorotic leaves with interveinal chlorosis and necrosis. Trunks viewed in cross section show dark streaking in few to most of the vascular elements. Pith is compacted and discolored; the surrounding wood is dry with a silvery sheen. Primary roots also show dark streaking in the vascular elements and total root biomass is reduced. Phaeoacremonium spp. were consistently isolated from the roots, crowns, and lower portions of the rootstocks of declining vines but not from adjacent healthy vines. Phaeoacremonium spp. grew slowly out of infected tissues, but sporulated abundantly in culture. Identification was verified from a published key (1). Phaeoacremonium chlamydosporum and P. inflatipes were isolated throughout the northern and central California production areas, but P. aleophilum was isolated only in Riverside County. Koch's postulates were completed for Phaeoacremonium spp. by dipping roots of 2-month-old Carignane grape seedlings (n = 80) in a 108 spores per ml suspension for 30 min. Plants were potted in an artificial soil mix and held in a growth chamber at 25°C. Over 50% of plants inoculated with Phaeo-acremonium spp. developed root, stem, and vascular symptoms within 8 weeks. Each of the individual pathogen species was reisolated from over 75% of the inoculated plants but never from the controls. Similarly, all three Phaeoacremonium spp. are associated with wilt and decline diseases in grapevines in Africa (1) and Europe (2) but this is the first report in North America. While several names for this disease have been used previously with older grapevines, including Esca, apoplexy, and black measles (3), we propose using Phaeoacremonium grapevine decline to describe the diseases caused by P. aleophilum, P. chlamydosporum, and P. inflatipes on young vines. References: (1) P. W. Crous et al. Mycologia 88:786, 1996. (2) P. Larignon and B. Dubos. Euro. J. Plant Pathol. 103:147, 1997. (3) R. Pearson and A. Goheen. 1988. Compendium of Grape Diseases. American Phytopathological Society, St. Paul, MN.

Alternating atrial electromechanical dissociation as contributing factor for pulsus alternans.

Ten patients with mechanical pulsus alternans were studied by echocardiography and mechanocardiography. All had been or were in congestive heart failure. An atrial mechanism for pulsus alternans could be identified in two patients: one with primary congestive cardiomyopathy and one after aortic valve replacement for calcific aortic stenosis. Each strong systole was preceded by an "a" wave, while each weak systole was not. This was documented on both the apexcardiogram and the M-mode echocardiogram. Since both patients were in normal sinus rhythm with regular PP intervals, it was concluded that alternating atrial electromechanical dissociation was either the underlying mechanism or contributed to the pulsus alternans. Thus, alternating atrial electromechanical dissociation exists and may cause pulsus alternans. Pulsus alternans is not necessarily the result of left ventricular myocardial dysfunction alone.