Pomegranate fruit rot caused by Coniella granati confirmed in Greece

Pomegranate (Punica granatum) is a rapidly developing crop grown for its fruits all over Greece. In autumn 2006 a fruit rot was observed in six pomegranate orchards in the area of Serres (Northern Greece, Central Macedonia). Symptoms first appeared as small circular spots on the fruits which later increased in size and developed into expanded brown lesions. Affected fruits rotted completely during storage causing yield losses of up to 50%. Abundant pycnidia covered the rind of rotted fruits (Fig. 1).

Isolations made on potato dextrose agar (PDA) gave rise to white mycelium colonies that formed large numbers of pycnidia after incubation at 25° C for 7 days. The fungus was identified as Coniella granati (Hebert & Clayton, 1963; Sutton, 1969) based on morphological characteristics. Pycnidia were globose, brownish in colour, with thin membraneous pseudoparenchymatic walls 49- 112 µm in diameter. Conidia were hyaline, one-celled, elongate, straight or slightly curved, 12-18 x 2-5 µm (mean 13.1 x 3.4 µm) (Fig. 2). One isolate was deposited at the Benaki Phytopathological Institute Culture Collection as BPIC 2593.

Pathogenicity tests were conducted by placing 5 mm diameter mycelial plugs on to scalpel wounds made in the surface of sterilized fruits. The tests were repeated three times. Inoculated fruits were placed in plastic bags and kept at 25° C for 10 days. Wounded fruits without mycelial inoculum were kept as controls. After 10 days all inoculated plants developed symptoms similar to those seen in the field. The pathogen was reisolated from the fruit.

Coniella granati is a widespread pathogen of P. granatum recorded in Brazil, Cyprus, Italy, Korea, North Carolina, The Netherlands, Pakistan (Farr et al. 2007) and Turkey (Yildiz & Karaca, 1973), but to our knowledge this is the first report of this pathogen causing fruit rot of pomegranate in Greece.