6 minute read
Long Game
Spur pruning a sound solution for pressured winter season
SOPHIE PREECE
LONG SPUR pruning could be a useful stopgap measure for Marlborough vineyards this winter, says viticultural advisor Mark Allen, in a video guide created for the industry. “We know we are faced with a unique challenge as the wine industry grapples with the consequences of closed borders and fewer experienced return winter pruners,” he says. The numbers will be improved with summer workers on extended visas and locals taking up the opportunity, but there will be a reduction in skill levels, he adds. Combine the need for training with an increased minimum wage, “and it will lengthen the pruning time and cost to complete the region’s vineyards”.
Mark has spent the past eight years running trials on several Marlborough blocks, assessing the efficacy and yields of spur pruning to various degrees, from the lightweight ‘mothball’ option - with a barrel prune and manual tidy up - right through to the ‘full monty’, where a vine is barrel pruned then manually tidied, decluttered and trimmed, retaining two long spurs in the head.
He began the work in order to develop an alternative pruning system to the four cane one typically used in Marlborough, allowing for more mechanisation, possible AI assist and less labour requirement. And it’s an easier handson job, says Mark. “With this spur pruning method, the vine can be done by one person and it’s all cutting through one year wood - so far less physically demanding - and is set up in a very regimented pattern.”
New Zealand Winegrowers, Wine Marlborough and the Bragato Research Institute commissioned the online guide to the pruning technique, with Mark demonstrating and discussing the potential future consequences of using spur pruning this season. In the video he discusses the importance of setting up one, two or three year cycles on the cordon, with long four-budded spurs. The buds are strategically placed along the cordon at 170mm to 200mm apart. The grower then ends up with the same bud number, if not slightly more, as they would have on a four cane vine, he says. “Fundamentally, you have the same number of buds, but you are putting them in a different place.”
The new pruning system could be a stopgap measure
Mark Allen gives guidance on how to prune using the four-cordon, long-spur method. Photo Jim Tannock
for a single year, with spurs left on the head of the vines for replacing canes the following year. “Then you just cut the cordons off next winter, which can easily be done with a Klima,” he says. “It’s very easy to go back to conventiontal pruning.” However, some growers may consider future proofing for labour shortages. “If you look outside winegrowing, at the likes of the apple industry, you see they changed their thinking from big free-standing trees, which are costly to manage and pick, to the trees they have now, which are 2 metres wide, 3m high, espaliered and regimented. It reduced their cost and enabled mechanised picking.”
Spur pruning in Marlborough can create more of a problem with mealy bug, but a good spray programme should allay those concerns, he says. However, he does anticipate resistance from growers who don’t see cordon pruning as right for Sauvignon Blanc, and are worried about crop levels. “But if done properly, there is no impact on yield,” he says, referencing trials blocks in Central Otago, Nelson, North Canterbury and Marlbrough.
“It needs to be looked at as an alternative simplified pruning system for now, and even a future strategy, because we know we can get the same yields, and it can be done quicker and for less cost than conventional Klima cane pruning.” The main motivation this season is the fact that it is so easy to teach and supervise, says Mark. “They don’t have to be that strong or that skilled. Its’ a very straight forward system”.
Prime cuts
Pruning research brought to the fore
SOPHIE PREECE
PRUNING MARLBOROUGH Sauvignon Blanc immediately after harvest can substantially extend the pruning season, with no increased risk of trunk disease. That’s one of the findings complied by the Bragato Research Centre (BRI), in a fact sheet on pruning options under a labour shortage.
As the country heads into winter with its borders closed and vineyard labour impacted, the fact sheet looks at the options and potential consequences of spur pruning (pg16), combined mechanical and spur pruning, and extending the pruning season by starting earlier and finishing later than typical.
BRI brought together relevant and up-to-date research from industry partners, including findings that pruning Marlborough Sauvignon Blanc immediately after harvest can extend the pruning season by as much as 25%, reducing the labour demand.
In colder regions like Marlborough and Central Otago, leaf senescence is observed as the fruit ripens, with little post-harvest carbohydrate accumulation. So while early pruning is not recommended in warmer regions - where post-harvest photosynthesis is important for the accumulation of carbohydrate reserves - Marlborough growers are able to get cracking sooner. “Research has shown that early season cane pruning (10 days post harvest) has no adverse effect on Marlborough Sauvignon Blanc yield or carbohydrate reserves in the vine trunk,” the fact sheet explains. “The same is thought of early season spur pruning.”
Furthermore, recent trials from the Vineyard Ecosystems Programme indicate that spores for fungal grapevine trunk diseases (GTD) - Botryosphaeria and Eutypa dieback - are lower earlier in the pruning season. “The findings show that you can prune in early autumn with no increased risk of GTD infection, if there are no rain
Photo Richard Briggs
events,” the fact sheet states. However, prompt protection of pruning wounds is still necessary, and sap flow may displace initial applications.
When talking of late season pruning, the paper notes that it can delay budburst, mitigating spring frost risk. However, “late pruning delays vine phenological development and may result in inadequate soluble solids accumulation by harvest”, it warns, noting a greater risk in cooler grape growing areas, or in seasons with a later harvest. “Risk associated with autumn rainfall and botrytis due to a longer hang time is also a consideration.”
BRI chief executive MJ Loza says even before the wine industry was announced as an essential service on March 23, the BRI looked ahead to what members would need heading forward. They sought insights from industry contacts across the wine regions, including growers, and large and small wine companies, and were given “a steer” to look at pruning options in a labour shortage, and options for mothballing vineyards, if needed.
The guide was pulled together swiftly, but with some companies choosing to prune early, it was out just in time, MJ says. The BRI will update information as required, and is inviting industry feedback in order to find the gaps in the research knowledge base. That could lead to research programmes going forward, enabling the industry to learn from this experience. Some of that feedback is already being put into action, with the BRI developing a calculator that will enable growers to plug in their specific details and compare potential costs and yields under different pruning scenarios.
Find out more at nzwine.com Search 'pruning' in the members section of nzwine.com for: • BRI fact sheet • Video on how to prune using the four-cordon, longspur method • Fact sheet on mothballing vineyards • Fact sheet on spray applications, to protect pruning wounds on dormant vines
