First Report of Embellisia hyacinthi Causing a Leaf Spot and Bulb Skin Spot Disease on Scilla peruviana in California.

The genus Scilla (Hyacinthaceae) includes more than 50 species of perennial, flowering bulbs grown in landscapes worldwide. In December 2000 and May 2009, an unknown leaf spot disease on Scilla peruviana was submitted to the California Department of Food and Agriculture Plant Pest Diagnostic Lab. Samples were collected during routine phytosanitary inspections of production fields in Santa Cruz County in 2000 and Monterey County in 2009. The disease was detected before plants flowered in one field at each location each year and appeared to have a scattered distribution. Foliar spots were large, elliptical to oblong with grayish black centers and brown margins. Yellow halos surrounded many of the spots. Examination of the bulb material revealed small necrotic patches on the outer bulb scales. A rapidly growing fungus was isolated on one-half-strength acidified potato dextrose agar (APDA) from the sporulating leaf spots and necrotic patches on the bulbs. The colonies were greenish gray and became dark olivaceous with age. Dictyospores, which formed on simple to branched, geniculate conidiophores, were oblong, fusiform or obclavate and usually had a triangular apical cell. They were initially hyaline, turning olivaceous brown with age. Conidia measured 14 to 39 × 8 to 13 µm (average 24.6 × 9.9 µm) typically with two to four (but up to seven) thick, transverse septa and one to two longitudinal septa. Morphologically, the fungus matched the description of Embellisia hyacinthi de Hoog & Miller (1,3). To confirm pathogenicity, four leaves of four S. peruviana plants were inoculated by taking colonized mycelial plugs from 2-week-old cultures and placing them in a plastic screw-cap lid filled with sterile water. The water plus mycelial plug suspension in the lid was then clipped to the adaxial side of a pushpin-wounded leaf (4). Plants were placed in a dark dew chamber at 20°C for 48 h and then moved to a growth chamber at 20°C with a 12-h photoperiod. After 48 h, the clips, caps, and plugs were removed. An equal number of control plants were wounded and mock inoculated with noncolonized APDA agar plugs and the experiment was repeated. Leaf lesions were visible 3 days after clip removal and expanded to an average of 26 × 10 mm, 14 days after inoculation. Sporulation was observed in the lesions after 5 to 7 days and the fungus was isolated from all inoculated leaves. No symptoms developed on the control leaves. DNA sequencing of the internal transcribed spacer region of the isolate (GenBank Accession No. HQ425562) using primers ITS1 and ITS4 matched the identity of E. hyacinthi (2,4). E. hyacinthi has been reported as a foliar and bulb pathogen on Hyacinthus, Freesia, and Scilla in Japan and Europe including Great Britain. Bulbs infected with E. hyacinthi are generally less sound and less valuable than noninfected bulbs (1). To our knowledge, this is the first report of the disease on S. peruviana in California. References: (1) G. S. de Hoog and P. J. Muller. Neth. J. Plant Pathol. 79:85, 1973. (2) B. Pryor and D. M. Bigelow. Mycologia 95:1141, 2003. (3) E. Simmons. Mycotaxon 17:216, 1983. (4) L. E. Yakabe et al. Plant Dis. 93:883, 2009.

First Report of Ramularia carthami, Causal Agent of Ramularia Leaf Spot of Safflower, in California.

Ramularia leaf spot was identified in several fields of safflower (Carthamus tinctorius) near Gridley, CA in June 2005. Numerous circular to irregularly shaped brown lesions, 3 to 10 mm in diameter, on both sides of leaves and flower bracts resulted in stunted plants and reduced seed production. In two of the fields, nearly all plants were affected, yields were severely reduced, and the crops were abandoned. Ramularia carthami Zaprom. was identified on the basis of morphology of reproductive structures on colonized leaves (1). Hyaline, thin-walled, aseptate conidiophores (2.6 to 4.3 × 28.8 to 72.0 µm) were produced in fan-like fascicles borne on hemispherical stromata (21.6 to 31.2 × 24.0 to 36.0 µm). Hyaline, smooth, cylindrical to fusiform conidia (7.2 to 12.0 × 19.2 to 40.8 µm), 1 to 3 septate or rarely aseptate were produced singly or in short chains. The fungus was isolated from symptomatic leaves and bracts surface disinfected for 1 min in 0.5% sodium hypochlorite and incubated at 25°C on acidified potato dextrose agar (APDA). Colonies of the fungus were white with irregular margins and were slow growing. After 3 weeks, colonies were approximately 3 cm in diameter. Conidia were not produced in culture. To conduct pathogenicity tests, three 3-week-old safflower plants grown in the greenhouse were sprayed with an aqueous suspension of mycelial fragments of the fungus. Inoculum was produced by macerating a 3-cm-diameter APDA culture of the fungus in 30 ml of water. Noninoculated control plants were sprayed with water. All plants were covered with plastic bags for 48 h on a greenhouse bench. Greenhouse temperatures ranged from a minimum of 20°C to a maximum of 27°C. After 7 days, all inoculated plants developed symptoms, and the fungus was reisolated from lesions. Conidia from lesions were suspended in water and diluted to a concentration of 1 × 105 conidia/ml and used as inoculum for additional pathogenicity tests. Three plants were sprayed with the conidial suspension or water as above. Lesions developed on the inoculated plants in 7 days, and the fungus was reisolated. No symptoms developed on plants sprayed with water. Both pathogenicity tests were repeated once. Sequence of the internal transcribed spacer region of rDNA of the fungus was deposited in GenBank (Accession No. DQ466083). To our knowledge, this is the first confirmed report of Ramularia leaf spot of safflower caused by R. carthami in California. Reference: (1) Morbi Plant. Script. Sect. Phytopath. Hort. Bot. Prince. USSR 15:142, 1926.

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.