Moria dell’actinidia nel veronese: anomalie climatiche, struttura del terreno e ruolo dei patogeni.

A vine decline of kiwifruit (Actinidia deliciosa, A. chinensi) was observed in 2012 and 2013 in about 600 hectares in the province of Verona (Northern Italy). During the last two years, a progressive vine decline took place during summers with high temperatures (over 35C °) requiring copious furrow irrigation, and with mild temperatures and abundant rainfall during winter and spring that caused long periods of soil waterlogging. The diseased plants died after a gradual blight of the leaves. Rotting of the roots intermediate in diameter and of the distal rootlets were associated with all cases of decline. Phytophthora and Pythium species were isolated from the decayed roots, were plate purified and identified by sequence analysis of the internal transcribed spacer (ITS) region of the rDNA amplified with specific primers. Pathogenicity of the Phytophthora isolates was verified with experimental inoculations of kiwifruit plantlets:typical symptoms of the decline in the leaves were caused by isolates of Phytophthora cryptogea. This is the first report of Phytophthora and Pythium presence in plants with root rot and vine decline of kiwifruit in Northern Italy associated to anomalous climate condition. Keywords: soil texture; irrigation; rain; feeder roots