South Africa Wine Technical Yearbook 2025

role in improving the soil carbon content, which in turn can improve the storage of reserves in the soil. The roots in the soil also increase aggregate formation. This means that a better soil structure is formed which enhances water infiltration, aeration and root penetration. Naturally, the plant is then better able to accumulate reserves and ensure that more elements are stored and captured in the soil. Soil compaction In the case of compacted soils, the post-harvest strategy should be adjusted to first alleviate the compaction before fertiliser is applied. Root pruning should be avoided at all times and only considered as a last resort if soil compaction cannot be uplifted with any other methods. Alternative options to uplift compaction, are cover crops and chemical correction of the Ca-Mg ratio, for example. In many cases, compaction occurs due to a chemical imbalance in the soil. A mechanical action will only uplift the compaction temporarily, after which the soil will become compacted again. Conclusion Post-harvest fertilisation, together with the accumulation and storage of sufficient reserves, is critically important to ensure optimal bud break and subsequently a good harvest in the next season. It is thus crucial to keep the grapevine and soil as healthy and optimal as possible to enable maximum build-up of reserves post harvest. It can also be beneficial to divide the maintenance fertilisation into two instalments to prevent nutrients from being washed out and also allow the plant sufficient time for uptake. This strategy will also limit the stimulation of regrowth. 

Healthy leaves are vital to ensure reserve accumulation – disease control post harvest will be necessary in this case.

Disease control The leaves of the grapevine should be protected at all costs. Ensure that harvest machine settings are correct to minimise leaf damage. In cases where disease pressure was high during the season, it is critically important to spray immediately after harvest to protect the vine’s leaves. Wettable sulphur and copper should provide sufficient efficacy and are also the most economic options. To achieve adequate nutrient uptake, it is paramount that leaf transpiration should still take place, while photosynthesis will ensure that enough carbohydrate reserves can be

stored. Photosynthesis also ensures proper cane ripening. Weed control Weed control can be applied on the berms to limit competition for water and nutrients when the post-harvest fertilisation is applied. The control of perennial weeds, especially couch grass, can be very beneficial at this stage, as the herbicide is translocated to the roots. Cover crops If soil moisture is sufficient, a seedbed can be prepared in advance. Also make sure that good quality seed is obtained, free from weeds like ryegrass. Cover crops play a major

Reference https://www.wineland.co.za/post-harvest-strategy-for-maximum-reserve-accumulation-in-grapevines/

For more information, contact Klaas Coetzee at klaas@vinpro.co.za.

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TECHNICAL YEARBOOK 2025