Pruning is defined as the act of cutting away dead or overgrown branches or stems, especially to encourage growth. Many of us have experience with pruning rose bushes in winter, to ensure new growth and more flowers in the following spring. Similarly, grapevines need to be pruned in the winter-time, to ensure optimal growth and fruit-bearing in the season leading to harvest.
Grapevines are creeping plants, and the key to successful pruning is to work with the creeping nature of the vine. How you choose to prune can dictate things like fruit-load, and help control vigour in the vineyards. These decisions can be complex, with choices like type of trellising, the direction of the rows, the aspect of the vineyard and the type of soil all influencing the final call on how to prune that specific block.
Here at Oldenburg, we’ve been working with specialist pruning training institution – Simonit & Sirch – for the past three years, to adopt an improved method of pruning that ensures longevity of the vines. Older pruning techniques have the effect of creating a large amount of wounds, which create scar tissue on the cordons (or “arms”). This scar tissue eventually starts blocking the sap flow inside the plant (remember, plants – just like animals – are living things that rely on the internal movement of water and nutrients to keep their tissues healthy and growing).
The perils of limited sap-flow include uneven ripening, lack of uniformity in the bunches, and the cordon drying out. When the sap-flow is too inhibited, the tissue starts to die off and in extreme cases, the whole cordon dies. The wounds from older pruning methods can also invite a fungus – Eutypa lata – which infects the vine and causes Eutypa dieback disease, one of the major trunk diseases of grapevine. This fungus grows slowly, causing progressively more damage; stunting shoots, killing spurs and trunks and eventually affecting the entire vine.
With all these things to keep under control, an optimal pruning method is essential to the health and longevity of the vine. The Simonit & Sirch method is used to curb these potential problems by keeping the channels inside the cordons open for optimal sap flow. Risk is minimised through a number of techniques, including avoiding unnecessary pruning and ensuring the wounds from the cutting are as small as possible.
The techniques are also applied differently, as required for each particular block. As an example, the OV14 block of Merlot receives a lot of wind in summer. As a result, the block is pruned to produce fewer shoots. Reducing the number of shoots helps to strengthen those that do develop, making them more resistant to the strong South-Easter.
By better understanding the seemingly simple act of pruning, we are investing in healthier vineyards, that will produce the best quality grapes for many decades to come.
