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New Zealand Plant Protection 65 (2012): 289

Infection of ZESPRIŽ GOLD kiwifruit (Actinidia chinensis 'Hort16A') lenticels by Pseudomonas syringae pv. actinidiae

N.J. Larsen, P.W. Sutherland, I.C. Hallett, M.K. Jones, I.P.S. Pushparajah and K.R. Everett


Pseudomonas syringae pv. actinidiae (Psa) is a bacterium whose virulent form (Psa-V) causes severe infections of kiwifruit, particularly Actinidia chinensis 'Hort16A'. Lenticels on kiwifruit canes function as pores, allowing gaseous exchange. The lenticellular structure penetrates through the periderm, potentially allowing bacterial entry and subsequent cortex infection. Bacteria have been observed inside and directly below lenticels from ca 3-year-old woody tissue from the field. To investigate this pathway of bacterial infection further, lenticels from three wood ages were inoculated with a strain of Psa-V at 109 cfu/ml. Brown staining was observed on lenticels 3 days after inoculation on the youngest wood (< 1 year old). Lenticels were sectioned 2 and 4 weeks after inoculation, and isolations were conducted from sterilised tissue after 4 weeks. Psa was visible inside lenticels of the youngest wood 2 weeks postinoculation, and was also isolated from the youngest tissue after 4 weeks. Bacteria were not observed in lenticels of older wood, and Psa was not isolated.

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