RESUMEN
For several years, a leaf spot disease has been observed on Betony, Stachys officinalis (synonym Betonica officinalis), in an experimental field in Kazanlak, Bulgaria. The round to somewhat angular spots (6 to 8 mm diameter) are dark brown with a pale center and have a chlorotic halo. A Phoma species isolated from the lesions formed regular to irregular, light brown colonies on potato dextrose agar (PDA). The isolate was studied as described by de Gruyter and Noordeloos (2). After 7 days, the growth rate was 43 mm on oatmeal agar and 33 mm on malt agar; the colonies were olivaceous gray-to-glauceous gray with a regular outline and with finely floccose, white-to-olivaceous gray aerial mycelium. Pycnidia, produced after 2 weeks, were ostiolate, globose to subglobose, 120 to 280 µm in diameter, citrine or honey, and later olivaceous to olivaceous black. The conidiogenous cells were globose to bottle shaped, 2 to 6 × 3 to 5 µm. The conidia were hyaline and unicellular, 5 to 7.5 × 2.5 to 4.2 µm, cylindrical to ellipsoidal with several small, scattered guttules. Chlamydospores were absent. According to these in vitro characters and after comparing the isolate with several Phoma isolates present in the culture collection of the Dutch Plant Protection Service, Wageningen, the Netherlands, the fungus has been identified as Phoma strasseri Moesz. The pathogenicity of the isolate was confirmed by artificial leaf inoculation of potted S. officinalis plants with a spore suspension (8 × 106 spores per ml) kept in a moist chamber for 48 h at a mean average temperature of 16°C. Leaf spots observed 4 to 5 days after inoculation were similar to those observed in the field. P. strasseri was subsequently reisolated from the spots. P. strasseri (synonym Phoma mentae Strasser) has been recorded as the cause of rhizome and stem rot on mint, Mentha spp., in Europe, Japan, and North America (3). In addition, this fungus has been found in New Zealand (strain identified at the Dutch Plant Protection Service, unpublished data). To our knowledge, this is the first report of P. strasseri on S. officinalis in Bulgaria. P. strasseri may produce septate conidia and, therefore, can be classified in Phoma section Phyllostictoides Zherbele ex Boerema (1). P. strasseri clearly differs from other Phoma species described on Lamiaceae: Phoma leonuri Letendre (Phoma section Plenodomus (Preuss) Boerema et al., pycnidia scleroplectenchymatous, conidia aseptate, 3.5 to 5.5 × 1.5 to 2.5 µm), Phoma dorenboschii Noordel. & de Gruyter (Phoma Sacc. section Phoma, conidia aseptate, 3 to 5.5 × 2 to 2.5 µm, producing dendritic crystals in vitro), and Phoma valerianae Henn. (Phoma Sacc. section Phoma, conidia aseptate, 2.5 to 4 × 1.5 to 2 µm). Occasionally P. strasseri has been isolated from other Lamiaceae, namely Monarda didyma (Dutch Plant Protection Service, unpublished data). There is also a report from Valeriana sp. (3). References: (1) G. H. Boerema. Mycotaxon 64:321, 1998. (2) J. de Gruyter and M. E. Noordeloos. Persoonia 15(1):71, 1992. (3) C. E. Horner. Plant Dis. Rep. 55:814, 1971.
RESUMEN
During late summer 1996 to 1997, 27 to 30% of Gypsophila paniculata (baby's-breath) plants were noted as diseased in an experimental field (Kazanlak, Bulgaria). Symptoms on lower and middle leaves consisted of small circular spots, with light brown centers and reddish purple margins. Development of numerous spots (which grew larger) and, especially, damage to the midrib led to withering of leaflets. Conidiophores of the isolated fungus were dark, formed singly or in clusters, were unbranched with three to eight septa, and were 40 to 120 µm long. Conidia, produced in branched chains (four to six conidia or longer), were brown, globose, and ovate to pyriform with short beaks, contained four to five transverse and zero to two longitudinal septa, and were 36.6 to 46.6 × 10.0 to 13.3 µm. The fungus was identified as Alternaria alternata. Pathogenicity was confirmed by artificial inoculation of potted G. paniculata and Dianthus caryophyllus plants. Conidia (2 weeks old) produced on potato dextrose agar were sprayed on plants in a 5 × 103 suspension, and plants were incubated at 20 to 24°C in a moist chamber for 2 days. Lesion development in both plant species was observed and recorded at 4 to 5 and 6 to 7 days after inoculation, respectively. Lesions were most numerous on G. paniculata. This is the first report of A. alternata on baby's-breath in Bulgaria. References: (1) M. B. Ellis. 1971. Dematiaceous Hyphomycetes. Commonwealth Mycological Institute, Kew, U.K. (2) E. G. Simmons. Alternaria themes and variations. Mycotaxon 37:79, 1990.
RESUMEN
In the spring of 1996, diseased plants of Trigonella coerulea were noted in an experimental area at Kazanlak, Bulgaria. The primary symptoms were leaf spots 8 to 2 mm in diameter, light brown then becoming gray and slightly zonate, and surrounded by a diffuse chlorotic margin. When single lesions occur the disease normally develops as a typical leaf spot. However, the development of more than one spot is followed rapidly by yellowing and withering of entire leaflets. Stem lesions usually begin at the point of leaf attachment, extend both directions about 15 to 20 mm, and often encircle the stems. Isolations on potato dextrose agar (PDA) yielded a slow-growing, gray fungus. Conidia from the isolated fungus when inoculated at 3.104 spores per ml on potted T. coerulea seedlings and kept in a moisture chamber for 48 h caused foliar spots in 5 to 8 days and sporulating structures similar to those seen in field observations. Simultaneous inoculation of T. foenum-graecum (fenugreek) plants produced similar symptoms, but the percentage of successfully inoculated leaves (3.6%) was lower than in T. coerulea (27.6%). Conidiophores of the fungus are dark, arising in clusters, unbranched, septate (1 to 3), and have small conidial scars. Conidia are hyaline, straight, multicelled (1 to 17), tapering at the base, and measured 30 to 212 × 4 to 6 µm. The pathogen was identified as Cercospora traversiana Sacc. and this is the first report of its occurrence in Bulgaria.
