Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

First report of Phytopythium vexans causing decline syndrome of Actinidia deliciosa 'Hayward' in Italy.

Abstract

A decline syndrome of kiwi (Actinidia deliciosa) has been reported in Italy since 2012 and currently affects an estimated 12% of the country's kiwifruit production area. The disease usually occurs in poorly drained soils prone to waterlogging, and it causes root rot, reduction of plant vigor, leaf curling, and sudden decline. During 2016 and 2018, 18 vineyards of the Piedmont region (northwest Italy) were monitored in June to October, and symptomatic vines were sampled in October to December. Experimental trials were set up in Friuli Venezia Giulia (northeast Italy) to reproduce the disease in a controlled environment by applying waterlogging to kiwifruit plants grown in 6.5-liter pots filled with sterilized and unsterilized soil from the diseased vineyards. Root rot and decline appeared in 90% of the plants when flooding conditions on unsterilized soil were used, whereas symptoms were not observed on plants grown on flooded sterilized soil, suggesting the involvement of a pathogen. The causal pathogen was isolated and identified as Phytopythium vexans based on morphological characteristics, molecular data (sequence analysis of the rDNA gene internal transcribed spacer (ITS), large subunit (LSU) rDNA, and cytochrome oxidase I (COI) region) and pathogenicity test. This is thought to be the first report of P. vexans causing kiwifruit decline syndrome in Italy.