At the time of writing the pruning season is drawing towards an end as day length begins to lengthen and a few spring-like days lift our spirits.
The pruning season is the time when there is the greatest demand for labour in the region. Its not difficult to work out that it is also therefore a time of considerable expense. With a ball park figure of 50 million vines in the region and an average pruning cost of $1.20 per vine for pruning there is a lot of money changing hands.
So first of all to the practicalities. We need to prune vines for several reasons. Fruit grows on new growth and we cut back much of last year’s growth to train the vine to produce fruit in one or two strips – called the fruiting zone – so that it can be easily managed. The number of bunches of grapes is limited to ensure a lowish yield of high quality fruit and the bunches need to be spaced out evenly so they have room to grow, they are not crowded together causing disease and they get plenty of sunlight.
There are a number of different types of pruning to achieve this but the predominant one is Marlborough is vertical shoot positioning (VSP) where a number of short canes are wrapped on to horizontal wires – the fruiting wires. One or two short canes or spurs are also left or provide new canes for the following season’s pruning. So you are pruning with an eye on the vine for the next two seasons.
The pruning season used to start once the leaves had fallen and the vines were dormant. It is important to finish before the buds start to burst in the spring. As spring gets closer the sap starts to rise in the trunks and the buds swell. At this time they are very susceptible to damage by strippers and wrappers so early pruning is best. Recent studies have suggested vines can be pruned before leaf fall with little detriment and this has extended the pruning season and taken a bit of pressure off.
The pruning gangs work in three stages. First come the pruners, who select which canes they are going to keep and cut the rest. Depending on the variety, the age of the vines, the soil and the desired fruit, they may retain one to five canes. Next in line are the strippers, whose job is not quite as exciting as it might sound. The pruners leave all the discarded canes caught up in the wires and the strippers’ job is to remove all of these – strip them out. The stripped out canes are laid down the middle of the rows ready for mulching when the whole job is finished. Last come the wrappers who clean up the selected canes, removing any side shoots or old tendrils, wrap the cane around the fruiting wire and tie it down at the end with a freezing bag tie. Job done.
Up until recently this whole job was done by hand, now there are machines that can do some of the stages, particularly the stripping out. The machines are improving all the time, in the early stages they did a fair bit of collateral damage but still most of the work is done by hand. Recent estimates suggest that pruning all of Marlborough’s vines could take around 10 million hours of labour. So the benefits of developing machines that do a quality pruning job are high.Much of the labour comes from overseas, particularly the Pacific Islands and also Thailand. Many Pacific Island workers come in the the government’s RSE programme which allows them to work in horticulture for up to seven months. It must be something of a shock for Islanders to experience working on a frosty morning, but many return each season.
This photo shows a pruned vine at bud burst. Each of the buds on the tied down canes produces a shoot which grows upwards. Because the buds are spaced out the vertical canes are nicely spaced – hence the name vertical shoot positioning. Each of these vertical shoots will produce 2 or 3 bunches. Some of the bunches may be removed later in the season to maintain fruit quality. In this photo you can see the tiny flowers developing, the precursor to a bunch. More of this in a future blog.
Of course if you join Na Clachan on a Marlborough wine tour Helen or Chris can show you all this in the flesh, explain more about other types of pruning and help you find the wine that suits your palate.