First report of Pseudomonas syringae pv. actinidiae causing kiwifruit bacterial canker in New Zealand Kerry R. Everett & Robert K. Taylor & Megan K. Romberg & Jonathan Rees-George & Robert A. Fullerton & Joel L. Vanneste & Mike A. Manning Received: 15 July 2011 /Accepted: 12 August 2011 /Published online: 29 September 2011 # Australasian Plant Pathology Society Inc. 2011 Abstract Leaves from gold kiwifruit plants, Actinidia chinensis, with dark brown angular spots and flowers that were brown and wilted, first yielded non-fluorescent bacterial colonies following isolation. These bacterial colonies were identified by diagnostic polymerase chain reaction (PCR) as Pseudomonas syringae pv. actinidiae. These samples were obtained from the Te Puke region of New Zealand. All isolates were Gram negative and were levan positive, oxidase negative, potato soft rot negative, arginine dehydrolase negative and tobacco hypersensitivity positive (LOPAT 1a). Sequences of the gyrB and the rpoD genes of these isolates were 100% homologous to sequen- ces of P.s. pv. actinidiae deposited in GenBank including the type strain. Koch’ s postulates were proven by pathoge- nicity tests on kiwifruit seedlings. Keywords Actinidia chinensis . Pseudomonas syringae pv. actinidiae . Fluorescence . Te Puke . New Zealand Kiwifruit (Actinidia spp.) is an economically important fruit crop grown in New Zealand, Italy, France, Chile and many other countries. In New Zealand, kiwifruit earns c. $NZ1 billion per annum, and is the second most important horticultural export crop by value. Kiwifruit originates in Asia, and since the commercialisation of Actinidia deliciosa ‘Hayward’ by New Zealand growers and government agencies in the 1980s, a breeding programme based on the importation of germplasm from Asia has been estab- lished in New Zealand (Ferguson and Huang 2007). In the early 1990s, the first economically significant product of the government and industry-sponsored breeding programme was commercialised (Actinidia chinensis ‘Hort16A ’) and this variety is now grown throughout the world. A further species of kiwifruit (A. arguta) has also been commercialised (Warrington and Weston 1990) by New Zealand breeders, and is now marketed as Kiwiberry. Pseudomonas syringae pv. actinidiae (Psa) was first described causing a disease of kiwifruit (Actinidia deli- ciosa) in Japan in 1989 (Takikawa et al. 1989). Since then it has been reported from Korea (Koh and Lee 1992), Italy (Scortichini 1994), Portugal (Balestra et al. 2010), China (CABI and EPPO 2008), France (Vanneste et al. 2011a; EPPO 2010), and Chile (Anonymous 2011). This pathogen can cause serious symptoms of cane die-back and vine death, and less serious symptoms of leaf spotting and flower wilting, accompanied by flower and bud drop (Serizawa et al. 1989). Psa is pathogenic on all commercial K. R. Everett (*) : J. Rees-George : R. A. Fullerton : M. A. Manning The New Zealand Institute for Plant & Food Research Limited, Mt Albert Research Centre, 120 Mt Albert Road, Auckland 1025, New Zealand e-mail: Kerry.Everett@plantandfood.co.nz J. L. Vanneste Ruakura Research Centre, East Street, Hamilton 3214, New Zealand R. K. Taylor : M. K. Romberg Plant Health & Environment Laboratory, Investigation & Diagnostic Centres, Ministry of Agriculture and Forestry, 231 Morrin Road, St Johns, Auckland 1072, New Zealand Australasian Plant Dis. Notes (2011) 6:67–71 DOI 10.1007/s13314-011-0023-9