Pollen research results

A two-year research project which investigated the impact of applying pollen naturally contaminated by Psa, to an orchard already infected with Psa, has now been completed.

Trap plants were hung in the kiwifruit canopy to allow visualisation of disease (leaf spotting) and comparisons made between trap plants that were covered and uncovered during artificial pollination rounds. The results showed disease incidence in the canopy was not increased by the pollen application.

The project also looked at the percentage fruit set of flowers pollinated with Psa-free pollen, versus flowers pollinated with pollen naturally contaminated with Psa on this same orchard. Results showed that vine location had a greater influence on the percentage of fruit set than any effects resulting from using pollen naturally contaminated with Psa or not.

These findings are consistent with anecdotal evidence from Bay of Plenty kiwifruit growers, which previously suggested there was no significant increase in disease observed on orchards already contaminated by Psa following application of pollen milled from flowers from regions where Psa had been detected.

The research authors strongly recommended that although pollen naturally contaminated by Psa is not the main cause of Psa spread in the orchard, these results should not be used to justify using Psa-contaminated pollen or potentially contaminated pollen in orchards or regions where Psa is not present.

Under the National Psa-V Pest Management Plan (NPMP) KVH Protocols have been established for controlling the movement of risk items capable of spreading Psa-V including artificial pollination.

A cover note for this project can be read here. The full report will be available at a later stage.