As the kiwifruit industry's dedicated biosecurity agency, KVH continues to hold the lead in managing the spread of Psa within New Zealand.
This includes managing activities that support the South Island’s ongoing Psa area freedom status, including annual independent monitoring rounds, which are a key part of this programme.
Each year KVH and Mainland Kiwi select sites to be monitored, based on risk.
Factors considered include blocks with more Psa susceptible male varieties (e.g., CK2, Bruce), or those affected by hail, flooding, or cyclone damage, or those generally showing poorer health. A range of varieties and block ages are included each year and across the course of the programme all South Island orchards have now been visited at least once. Monitoring is undertaken by KVH staff, and by AgFirst Consultants Nelson Motueka.
This year, AgFirst staff walked 15 blocks over 14 KPINS, and included Hayward, Gold3 and Arguta varieties from the Motueka and Waimea area. KVH monitored Hayward, Gold3 and both 2022 and 2023 grafted Red19, visiting sites in Riwaka, Motueka and Takaka.
As standard practice, teams forward any samples with Psa-like leaf spotting to Hill Laboratories Ltd for analysis. This year 11 samples were collected by the teams, and all returned a “Not detected” Psa-V result.
The leaf spotting seen is likely resultant of the presence of Pseudomonas syringae pv. actinidifoliorum (Pfm, previously named Psa-LV). Incidence of Pfm has reduced over time as South Island growers have incorporated more winter and spring copper sprays in their spray programmes. Here are some photo examples of the spotting.
This November, KVH also visited sites where unusual symptoms had been followed up through spring, and monitored blocks supplying budwood to the North Island, to verify processes are in place to ensure collection is only from healthy vines. Here are some photo examples of cankers to be excluded, and marked.
These process checks are important to ensure the Cook Strait continues to represent a defendable barrier to the spread of other kiwifruit industry pests and pathogens. Monitoring and testing of blocks is valuable to the Nelson-Tasman community and the industry, and regular contact with the regions provides valuable reminders of the need for all parties to remain vigilant to biosecurity risk.
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