Diagnostic Challenges for the Detection of Emerging Pathogens: A Case Study Involving the Incursion of Pseudomonas syringae pv. actinidiae in New Zealand

In November 2010, Pseudomonas syringae pv. actinidiae (Psa) was detected for the first time in New Zealand. This finding triggered one of the largest surveillance and diagnostic programmes seen in New Zealand’s horticultural industry. During this response, over 912 kiwifruit orchards and 14,500 samples were screened and tested for the presence of Psa. The initial objectives of the response were to confirm the causal agent, determine disease prevalence and identify possible mechanisms of spread with the aim of identifying management options to contain the outbreak. Molecular diagnoses and characterisation of the Psa strains isolated during the response was conducted using a range of techniques that included qPCR, rep-PCR fingerprinting, multilocus sequence analysis, and next generation sequencing. The usefulness and challenges of using the molecular techniques available at the time for Psa detection and characterisation during the response are discussed.