Waimea Nurseries (New Zealand) introduces dwarfing rootstock selections

Some selections of dwarf rootstocks for cherry Gisela® have recently been authorized for the New Zealand fruit industry and will be more widely available to growers starting in 2026. Waimea Nurseries in Nelson has confirmed that Gisela® 6 and Gisela® 12 are in production, while Gisela® 5, 13, and 17 are currently being imported and are in quarantine.

Gisela® 12 and 6 are currently being grown indoors in tissue culture at the Waimea Nurseries laboratory and are being tested in orchards in Central Otago, including Clyde Orchards and Suncrest Orchard in Cromwell. Trials of dwarf rootstocks for cherries are also underway in Hawke's Bay. Variety development manager Tallulah Simpson states that more of these will be available in commercial quantities by the end of 2026.

When Professor Dugald Close from the University of Tasmania visited New Zealand in July, he said that Australasia still has a long way to go before realizing the benefits available in America and Europe, such as the widespread availability of dwarf rootstocks.

Dwarf rootstocks for cherries offer great opportunities to create more intensive cultivation systems, but Waimea Nurseries claims that so far it has been difficult to propagate them in the nursery. “It’s not easy, and we are cautious,” says Kate Marshall, general manager of sales and marketing.

The advantage of growing rootstocks from tissue culture is that they are virus-free.

Growing on dwarf rootstocks, compared to the traditional Colt rootstock, allows growers to quickly produce very high volumes, explains Kate. In the past, fruit growers were reluctant to use them because they were costly and the investment paid off only if the soils had enough nutrients and if they could successfully implement the new changes in their orchard systems.

Tallulah states that New Zealand has fallen behind the US, Europe, and Chile regarding the availability of these rootstocks due to importation difficulties of plant material and because they require significant investment.

Gisela® has already been well marketed abroad, and Central Otago is ideal for the use of dwarf rootstocks, as it has a unique climate and soil conditions, as well as a range of different soil types throughout the district, explains Kate. But dwarf rootstocks require the utmost commitment from growers to make them profitable, and many growers realize this.

Clyde Orchards first planted a row of Gisela® dwarf rootstock cherries in 2018 as a trial, and their production looks promising. According to director Kris Robb, the issue was achieving enough fruiting production for the company, and to do this, a larger number of trees (for example, an entire block) is needed to work with.

To allow growers to manage their orchard systems more efficiently, large quantities of new rootstocks are needed. According to Kris, the lack of dwarf rootstocks for cherries has harmed the overall productivity of the sector. “Probably, the inability to obtain dwarf rootstocks has done a disservice to some underperforming varieties.”

Kordia, Regina, and Folfar are the three cherry varieties that come to mind, but he acknowledged that the challenges faced are both from growers and nurseries. “It took a long time to learn and for nurseries to refine their systems.”

More orchards will seek to begin using dwarf rootstocks as soon as they become available. “If you can harvest more fruit, harvesting costs go down. You end up with smaller and more compact trees, which are more efficient to prune and harvest,” explains Kris.

Growers will see their profits faster, and their yield per hectare will also be higher.” With Colt rootstocks still representing 99% of the sector, the new dwarf rootstocks will offer growers the opportunity to fruit in two years instead of the standard five. Michael Jones, a grower from Cromwell and Suncrest Orchard, has planted 10,000 trees at two different times, but he says it’s still too early to know how they will perform. He received some Gisela® 5 and 12 specimens in 2020 and planted more in 2022.

“We were given permission to graft and bud different varieties onto these stocks and to grow trees for our pergola system at a density of 4,000 trees per hectare. Success rates varied from 40% to 70% depending on the rootstock and variety. Usually, failure was due to rootstock growth and bud or graft failure, which allowed for re-grafting the rootstock.”

The grafting and budding were done on-site by contractors, and so far the experience has been positive.

“We appreciated the input from various people who advised us on what we could do or try in this situation, and it was nice to run ideas past people like Andy McGrath or Ronald Vermeulen and get their perspective on what we were doing.”Michael says that, given the possibilities offered by today’s cultivation systems, it will be interesting to see how the sector progresses over the next decade.

“We studied the use of dwarf plants because we were frustrated by the inconsistent yield and the time it took for less intensive plantations to reach full yield; also for the potential to maximize quality and size and reduce labor and other cultivation inputs.”

Of course, capital expenditure is a high cost, but his advice to growers is to try different solutions in their plots, “whether it’s two trees, two rows, or two hectares. If you don’t try, you can’t know. I’m really looking forward to seeing and working with our new blocks when they start their productive phase.”

With dwarf rootstocks, growers can also plant more trees per hectare, improving efficiency in land use. Over time, existing orchards can be upgraded to higher-density orchards, meaning less land use while maintaining the same volumes over a smaller area.

Richard Mills, technical consultant for Summerfruit NZ, states that dwarfing plants will be a great advantage for other cherry growing areas, particularly in the strong soils of Hawke's Bay. “The anticipation of the potential harvest period should also benefit consumers, thanks to a longer harvest season.”

He notes that good dwarf rootstocks for apples, which emerged about 20-25 years ago, have been a significant factor in allowing this group of products to make huge strides towards higher yields on smaller areas. Waimea Nurseries is currently propagating new selections of cherry dwarf rootstocks in an “Ellepot,” equipped with a paper membrane, which is grown indoors in a “Cravo” greenhouse (a greenhouse with an automatically retractable roof).

Read the full article: Krishak Jagat
Image: SL Fruit Service

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