Vine decline in kiwifruit: a phytosanitary emergency in the province of Verona (Northern Italy) climate change and effect on waterlogging and Phythopthora in North Italy.

A vine decline of kiwifruit (A. chinensis var. deliciosa ‘Hayward’) was observed in 2012 and 2013 in about 600 hectares in the province of Verona (Northern Italy). Kiwifruit had been growing in this area for about 30 years without any phytosanitary emergency. 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 indiameter and of thedistal rootlets was 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 kiwi 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.