Aspects still to solve for the management of kiwifruit bacterial canker caused byPseudomonas syringaepv.actinidiaebiovar 3

Abstract

The pandemic wave of kiwifruit bacterial canker, caused by Pseudomonas syringae pv. actinidiae (Psa) biovar 3, has caused, in recent years, severe economic losses in all major areas of kiwifruit production. After the initial discouragement, each country affected by the disease reacted promptly, trying to establish and promote phytosanitary and agronomic measures aiming at reducing the incidence and severity of the disease and the risk of further spread. Within this context, considerable efforts have been made by public and private research groups, strongly supported by ad-hoc projects funded by international, national and local political and commercial Institutions. Less than 10 years after the initial outbreak of May 2008 in central Italy (Latina province), management of the disease has reached a rather satisfactory level in many areas of cultivation worldwide, despite the endemic presence of the pathogen in orchards. However, if co-existence has been successfully achieved under some circumstances, some aspects of disease control still require particular attention. Among the others, these include: (i) the rapid occurrence of copper-resistant Psa and P. syringae pv. syringae strains in New Zealand and Italy, respectively; (ii) winter and spring frosts promoting an increase in the aggressiveness of the pathogen; (iii) susceptibility of the new gold and red cultivars; (iv) control measures to perform during plant dormancy; and (v) upgrading some agronomic techniques to prevent the multiplication and spread of the pathogen within and between orchards.