Te Puke’s claim to be the kiwifruit capital of the world may be endangered later this century unless the industry can come up with some climate change-resistant Green varieties, according to new research.
The research, carried out by NIWA climate scientist Dr Andrew Tait and Alistair Mowat of Tauranga-based consultants Thought Strategy, focused on the impact of climate change on the high-earning fruit. It paints a less than positive picture for the long-term future of the Green variety.
Dr Tait said that while the NIWA research was conducted specifically in the Te Puke district, climate change was expected to have a generalised effect across the entire Western Bay of Plenty.
He added that the work he and Mowat conducted was equally applicable to other fruit crops likely to be affected by the changes, including pipfruit.
Using an empirical NIWA climate model and crop data, the latest research has found the diminishing number of the winter chilling nights the Green variety requires will jeopardise its cropping ability, making it marginal by 2050 and “most likely” not viable by 2100.
The traditional temperature drop from May to July results in more flowers on Green vines, and an earlier flowering period. This has been accentuated in recent years by the use of hydrogen cyanamide-based sprays, which promotes bud burst.
However, the spray is not without its controversy, and Dr Tait said it may not always be an option with which to counter the loss of winter chilling effects.
The research has built on work conducted two decades ago, but now incorporated NIWA temperature data with high resolution mapping. From this they had determined inland areas of Bay of Plenty would provide viable planting areas, and even some districts within the Otago and Canterbury regions.
“But we do not think Bay of Plenty is done. It is a well-established industry there and that has to be deeply considered.”
Green kiwifruit accounted for 63 percent of the 137 million trays marketed by Zespri in the 2016-17 season, the balance coming mostly from the new Gold variety, which is being planted in increasing numbers.
Dr Tait said the most surprising outcome from their research was that regardless of what reductions were achieved in carbon emissions, the decline in vine productivity remained highly likely.
“All pathways resulted in a very similar type of scenario as their outcome.”
Given the kiwifruit industry’s vertically integrated nature, Dr Tait said there was a good case for industry bodies to take the lead with planting location, varieties and management techniques to help counter the creep of climate change.
“As an individual grower you are heavily invested and it is difficult to change your crop or your region. But as an industry such signals are important to lead those changes.”
Dr Tait said he took heart from how the industry had responded to the 2010 Psa outbreak crisis, which had resulted in a complete change in plant variety from the vulnerable Hort16a hybrid to SunGold, within two years.
Carol Ward, Zespri general manager for innovation, said the study highlighted how important it was for Zespri and the New Zealand kiwifruit industry to think longer term on the potential impact of climate change.
“We are a resilient industry, thanks to several factors. One is diversity – many orchardists grow more than one variety of kiwifruit. Another factor is that we are continuously working to develop and evaluate new cultivars of kiwifruit through the world’s largest kiwifruit breeding programme with Plant and Food Research.”
She said this gave the sector the potential to develop new cultivars with different attributes, including resilience to environmental risks and productivity under different growing conditions.
“It is a very long-term programme and one that is vital for being prepared for future change.” She said the industry was also innovating through different growing systems and solutions, including growing under shelter netting to protect against different climate risks in terms of short term seasonal factors, and longer term trends.
New Zealand Kiwifruit Growers Incorporated vice chairman Mark Mayston said the organisation would continue to advocate for growers through its ongoing work with industry stakeholders, including Zespri and Plant and Food Research.