First report of leaf spot of spinach caused by Pleospora betae in Spain.

The production of spinach (Spinacia oleracea L.) in Spain has increased 50% since 2009, mainly due to the commercialization of fresh-cut spinach leaves packaged in modified atmosphere containers. In October 2012, light brown leaf spots 1 to 2 cm in diameter with dark concentric rings were observed in a commercial spinach production area in Valencia Province, Spain. The initial outbreak comprised an area of about 3 ha with a 20% disease incidence. Symptomatic leaves from spinach cv. Apollo were collected in the affected area and were surface disinfected with 0.5% NaOCl for 2 min. Small fragments from lesions were placed onto potato dextrose agar (PDA) amended with 0.5 g streptomycin sulfate/liter. Fungal colonies developed after 3 days of incubation at 23°C from about 90% of the infected tissues plated. Isolates were transferred to oatmeal agar (OA) (1) and water agar (WA) amended with autoclaved pea seeds (2). Plates were incubated for 30 days at 24°C with 13 h of fluorescent light and 11 h of dark for mo...