Pathogens Associated to Kiwifruit Vine Decline in Italy

Abstract

Kiwifruit production has gained great importance in Italy, becoming a strategic crop in several areas. In recent years, the Italian kiwifruit industry has been threatened by the emergence of a new, idiopathic syndrome causing a severe and rapid decline, leading to vine collapse within two years from symptom development. The main symptoms associated to this syndrome are the disappearance of feeding roots, blocking of both stele and xylem vessels, root cortex breakdown, leaf necrosis, phylloptosis, twig wilting and plant death. Kiwifruit decline affects both Actinidia chinensis var. chinensis and A. chinensis var. deliciosa. Due to the similarity with other fruit trees idiopathic diseases, such as the rapid apple decline, we propose to name this disorder as kiwifruit vine decline syndrome (KVDS). The causes of KVDS are still unknown. However, KVDS is prevalent in soils affected by waterlogging or poor aeration, suggesting a physiological origin of this disorder. In addition, our experiments suggested a role of the rhizosphere microbial community, since healthy and KVDS-affected plants show distinct bacterial and fungal communities. Phytophthora spp. and Phytopythium spp. were more frequent in symptomatic plants (58.6%) than in asymptomatic ones (19%). Moreover, Desarmillaria tabescens were found only on symptomatic plants. Inoculation of potted kiwifruit vines with those pathogens resulted in KVDS symptom development. Finally, induced waterlogging conditions increased the incidence of pathogen isolation, but not the symptom development.

Early Identification of Root Rot Disease by Using Hyperspectral Reflectance: The Case of Pathosystem Grapevine/Armillaria

“…Armillaria spp. can parasitize a wide range of plant species in forests, both conifers and broadleaves [7], and in garden trees and shrubs [8], and it can cause extensive losses in fruit orchards, such as apples and berries [9], pears [10], peaches [11,12], and kiwifruits [13], as well as grapevines [14][15][16][17].…”

Prediction of the Kiwifruit Decline Syndrome in Diseased Orchards by Remote Sensing

“…KD spreads following an oil-spot pattern, with an astonishing speed that can compromise the whole orchard in only one or two growing seasons [2]. Currently, studies on KD are mostly focused on understanding the aetiology of the disease, which has not yet been fully clarified, but it seems that an interaction between waterlogging and several soil-borne pathogens is necessary to induce the disease [2,[10][11][12][13].…”

Pathogenicity of Phytopythium chamaehyphon: A New Player in Kiwifruit Vine Decline Syndrome of Actinidia chinensis var. deliciosa ‘Hayward’ in Italy

“…This genus can inhabit both water and soil, and requires free water for the zoospore movement and for the initiation of the infection, as many other oomycetes (de Cock et al 2015). Previously other oomycetes have been associated to KVDS: Phytopythium vexans (Prencipe et al 2020), Phytopythium helicoides (Donati et al 2020), Phytophthora infestans (Donati et al 2020), Phytophthora citrophthora and Phytophthora cryptogea (Tacconi et al 2015). It may be speculated that KVDS is enhanced if several pathogenic species are simultaneously infecting the roots, since the speed of symptom appearance and the disease incidence were higher in PC treatments compare to PCHA.…”

“…Phytophthora genera) seem to play a major role in KVDS (Savian et al 2020a;Donati et al 2020;Prencipe et al 2020), however, also fungi (genus Desarmillaria) and bacteria (genus Clostridium) have been associated with the disease (Donati et al 2020;Spigaglia et al 2020).…”