Archivio Journal of Plant Pathology

Abstract:

In a survey for diseases of the fern Pteridium aquilinum (L.) Kuhn, leaf samples with blight symptoms were collect- ed from grasslands in the Trabzon province (Turkey) in late spring of 2009. Initial symptoms appeared as small circu- lar spots, light brown in colour. Later, many became dark brown. A fungus, consistently isolated on potato dextrose agar (PDA) from symptomatic leaves, formed conidia singly or in short chains, dark brown, with 3-7 transverse and 0-4 longitudinal septa, 20-60×9-16 μm in size. The pathogen was identified as Alternaria alternata based on morphology char- acteristics (Simmons, 2007). For pathogenicity tests, inocula were prepared by growing isolates on PDA at 25°C for 15 days. Sterile distilled water (10 ml) was added to each plate and colonies were carefully scraped with a sterile needle. The resulting conidial suspension from each isolate (diluted to 5×105 CFU/ml) was used to infect 12 P. aquilinum plants, using an atomizer to spray leaves. After inoculation, plants were covered with polyethylene bags for 72 h to maintain a high humidity, after which the bags were removed and plants were kept under laboratory conditions until symptoms ap- peared. Ten days post inoculation, light brown spots were observed on inoculated leaves but no symptoms were seen on water-treated control plants. Koch’s postulates were ful- filled by re-isolating A. alternata from diseased leaves. Simi- lar symptoms caused by A. alternata on P. aquilinum were reported in UK (Godfrey, 1974). To our knowledge, this is the first report of A. alternata on P. aquilinum in Turkey.