Archivio Journal of Plant Pathology

Abstract:

In the course of a survey to determine the fungal pathogens of asparagus in Balıkesir province (north-western Turkey) brown sunken lesions with dark purple margins were observed on the spears. Pseudothecia and ascospores were looked for in overwin- tering plant debris. Diseased tissues were surface-sterilized in 1% sodium hypochlorite for 2 min and placed on potato dextrose agar medium. The isolated fungus was identified as Stemphylium vesicarium based on morphological traits (Ellis, 1971), i.e. brown, oblong to broadly ellipsoidal and verruculose conidia (20 to 45×15 to 22 μm), with cross and longitudinal septa; pale to light brown conidiophores with a dark smooth or minutely verrucu- lose band; bitunicate and clavate asci (190 to 150×25 to 33 μm); light brown and ellipsoidal ascospores (35 to 45×15 to 22 μm). The identification was confirmed comparing the sequence of a 544 bp product (accession No. JX397964) amplified from the ITS region of the fungus under study by PCR using the primers ITS1/4 (White et al., 1990) with that of a comparable region of S. vesicarium rDNA present in GenBank. Asparagus seedlings (45- day-old) were sprayed with a suspension of 5×104 conidia/ml, then covered with polyethylene bags for 48 h and kept for 21 days at 22±1°C and a 14 h photoperiod. Symptoms comparable to those seen in the field were obtained and the fungus was con- sistently re-isolated from the lesions. S. vesicarium (telemorph, Pleospora herbarum), is an asparagus pathogen first recorded in the USA (Lacy, 1982). To our knowledge, this is the first report of asparagus purple spot disease in Turkey.