A new wood decay of kiwifruit in Italy

A previously undescribed form of wood decay of kiwifruit (Actinidia deliciosa (A. Chev.) C. F. Liang et A. R. Ferguson) plants was observed in 8-10-year-old Emilia Romagna orchards in north-central Italy. Symptoms appear as unspecific interveinal chlorosis of the leaf, which later may become necrotic resulting in premature leaf drop. Fruits never grow as large as on healthy plants nor do they reach full maturity. This foliage chlorosis occurred on current season's shoots developing from canes growing horizontally from the cordon. Cross-sections of the wood show white rot areas surrounded by brown necrosis of hard consistency, preceding the white rot in the colonisation of the wood. Isolations from the zone of hard consistency onto Potato Dextrose Agar (PDA) medium yielded Phaeoacremonium aleophilum, P. inflatipes, P. chlamydosporum, P. rubrigenum, and to a lesser extent, Phialophora sp., whereas Phellinus conchatus was commonly isolated from white rot diseased tissue. Although pathogenicity studies on host plants are still being carried out, a strong similarity with esca disease of grapevine could clearly be noticed.