New Zealand is the third largest producer of kiwifruit in the world behind China and Italy. Despite the global pandemic, kiwifruit exports have shown no sign of slowing. In 2019, 149 million trays of green kiwifruit were produced for export. And the gold variety on supermarket shelves known as Zespri Sun Gold rose from 67 million trays to 75 million in 2020, proving popular with its smooth skin and perfect oval appearance.
But success of the Zespri Sun Gold variety has not been complete overall. In November 2010, the HORT 16A gold variety, was ravaged by the bacterial disease PSA. This variety of gold kiwifruit was smaller in size and had a flat, almost woody beak. The disease spread like wildfire.
"The general consensus is that PSA was imported on pollen," says award-winning scientist at Plant and Food Research professor Russell Lowe, who this year was awarded the Plant Raiser's Award by The Royal New Zealand Institute of Horticulture.
Very little was known about the disease in 2010, including how it behaved or travelled, and how fast it could spread. The news of PSA hit media headlines almost as quickly as the bacteria spread across the country.
"Once PSA spread from the original site across the Bay of Plenty and arrived on the Te Puke Orchard, visible signs of infection were seen right throughout the plants," Lowe told sunlive.co.nz. "One of our researchers did some forecasting based on the number of plants that were dying over a short period and estimated that within a year or two there wouldn't be a single kiwifruit plant left.”
Kiwifruit growers across the country were sent into a state of panic. And with approximately 100 scientists across the country working on ways to eliminate the disease, the only way to contain the spread of the bacteria was to eradicate any plants showing signs of disease.