First Report of Septoria pistaciae Causing Leaf Spot of Pistachio in Egypt

In May 2006, leaf spots were observed on approximately 60% of 8-year-old pistachio (Pistacia vera L.) trees in an orchard located at Rhafah, north of Sinai, Egypt. These spots were typically circular, or occasionally irregular, with white-to-light tan or gray centers and a purple or brown border measuring 1 to 5 mm in diameter, or occasionally larger on the upper leaf surface. A narrow, brown border surrounded the spot, and with age, the lesion cracked. Spots occasionally turned brown and closed to form blotches. Fungal isolates from the leaf spots were identified as Septoria pistaciae on the basis of characteristics of pycnidia and conidia. From the leaf spots, numerous black pycnidia were found that produced hyaline conidia, 3 to 7 septate, generally filiform although tapering at one end, and measuring 46 to 75 × 3 to 4 μm. Pycnidia were dark, separate, globe shaped with an ostiole from which conidia were extruded, and erupted through the surface of infected plant tissue. Conidia were produced on short conidiophores. Single conidial isolations onto 2% malt agar consistently formed slow-growing, dark green colonies. To confirm the pathogenicity of the isolate of S. pistaciae, a suspension of 5 × 10⁵ conidia per ml in water was applied at 1 ml per leaf to 20 leaves of 10 rooted cuttings of pistachio trees in 30-cm pots. Ten controls were misted with water only. All plants were covered with plastic bags for 48 h on a greenhouse bench. Greenhouse temperatures ranged from 15 to 20°C with a 16-h photoperiod. After 6 days, all inoculated plants developed symptoms, and the fungus was reisolated from lesions. No symptoms were observed on control plants. S. pistaciae was previously reported on pistachio in Texas and Arizona (2,3). Reports included mention of its occurrence in the United States (California), Asia (Armenia Republic of Georgia, India, Israel, Kazakhstan, Kirgizstan, Syria, Turkey, Turkmenistan, and Uzbekistan), and Europe (Albania, France, Greece, Italy, and Portugal) (1). To our knowledge, this is the first report of Septoria leaf spots of pistachio in Egypt. References: (1) T. Andrianova and D. Minler. Septoria pistaciae. Page 159 in: IMI Descriptions of Fungi and Bacteria. CAB International, Wallingford, UK. 2004. (2) A. Chitzanidis. Ann. Inst. Phytopathol. Benaki 10:29, 1956. (3) D. J. Young and T. Michailides. Plant Dis. 73:775, 1989.