Technical Yearbook 2024

Irrigation Sufficient soil moisture/water supply during the critical stages of the seasonal development of the vine, is essential for the build-up and mobilisation of carbohydrate reserves. The irrigation strategy must be especially closely monitored for the budding, flowering, fruit set and post-harvest stages. The regulated deficit-irrigation approach has been proven to control vegetative growth effectively and stimulate root development without sacrificing carbohydrate reserves. Soil and fertilisation Apply fertilisation wisely by basing applications on regular soil analyses. Precision applications (spot applications and timing) can decrease variation in growth and variation between blocks, which will allow more value to be added from even the most basic viticultural practices. Indirect practices contributing to the optimal functioning of the vine include the use of cover crops, mulches and organic material. These practices lead to better availability of nutrient contributions to conserve soil moisture, regulate soil temperature and supply organic material. All these actions will contribute to the accumulation of carbohydrate reserves.

PHOTO 3. Example of extreme cases of downy (top) and powdery mildew (bottom) infections which resulted in early leaf fall. Given that the crop must be ripened without active leaves, the plant will have to delve deep into the reserve pool, which will then be problematic for the next season.

Harvest Consistently balance the crop size with canopy capacity. An excessively large crop combined with low canopy capacity will most likely culminate in decreased carbohydrate reserve levels at the end of the season. Leaving grapes on the vine to a higher ripeness degree than the canopy can handle, too will have a negative influence on the reserve status. Together these practices will also shorten the recovery time during the post-harvest period, especially in late-ripening cultivars.

PHOTO 2. Competition from weeds for water, nutrients and sunlight also result in lower reserve levels.

Disease and pest control Follow a good disease- and pest-control programme to keep vineyard canopies healthy. This will lead to an effective canopy and optimal photosynthetic activity.

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TECHNICAL YEARBOOK 2024