First report of a new leaf spot caused by Plectosphaerella cucumerina on field grown endive (Cichorium endivia) in Italy.
During the summer of 2012, symptoms of a new leaf spot disease were observed in several commercial fields in Treviglio (Bergamo, Lombardy, Italy) on plants of curly (C. endivia var. crispum) and Bavarian (C. endivia var. latifolium) endive. The initial symptoms on the leaves of the affected plants consisted of small (1.0 mm) black-brown spots of irregular shape, later coalescing into larger spots up to 10-15 mm in diameter. Eventually, spots were surrounded by a yellow halo. Affected tissues rotted rapidly under highly humid conditions. Disease severity was greatest at 75-90% relative humidity and air temperature between 23 and 30°C. This disease resulted in severe production losses. In one farm with three fields, 5-13% of the plants were affected. The pathogen was identified as a Plectosphaerella sp. based on morphological characteristics. The internal transcribed spacer (ITS) region of the rDNA was amplified using primers ITS1/ITS4 and sequenced. BLAST analysis of the 530-bp segment obtained from C. endivia var. crispum isolate PLC28 and of the 527-bp from C. endivia var. latifolium isolate PLC 30, respectively, showed 99% similarity with the sequence of P. cucumerina [Monographella cucumerina]. This is thought to be the first report of P. cucumerina on endive.