Winetech Technical Yearbook 2022

APRIL

UNIWINES VINEYARDS’ QUALITY STRATEGY FOR HIGHER-YIELDING VINEYARDS

BY PIERRE SNYMAN

INTRODUCTION uniWines Vineyards is a cellar located in the Breedekloof region. This cellar has approximately 3 000 hectares of vineyards and is very diverse in terms of the cultivar composition of plantings. There is a very good strategy at uniWines Vineyards whereby each vineyard block is assigned a specific wine goal. The three main wine goals are premium cultivar, cultivar and table wine. To qualify for a cultivar wine goal, certain management actions are required in the vineyard, and the wine made from the grapes must achieve a specific score in a blind tasting. The one-wire or so-called high-wire hedge system is wide ly used. Some of these blocks are mechanically managed and pruned to increase yield. The challenge is achieving the increased yield without compromising on wine quality, which has prompt ed a cellar project in this regard. Dr Philip Myburgh, previously from the ARC in Stellenbosch, was approached and is still involved in this project that has been launched. This article aims to describe the project and its prelim inary results and elaborate on the pressure bomb use. Nicholas Bruyns is the viticulturist of uniWines Vineyards and manages

the project with Pierre Snyman in his involvement as a Vinpro consultant. METHODOLOGY Seven blocks were identified that could be described as high yielding (for the purposes > 20 t/ha). These seven blocks consist of one-wire hedge systems, which are mechanically managed. The cultivars include Pinotage, Cabernet Sauvignon, Merlot, Shi raz, Chenin blanc (photo 1), Chardonnay and Sauvignon blanc. A meeting was held with the producers involved, and the project was presented to them. The focus areas were fertilisation, prun ing and irrigation, and it was decided to initially only implement the irrigation component of the proposed project. All the relevant data from these blocks were collected and processed (table 1). From this, it clearly emerged that all the blocks were managed differently regarding irrigation. The plan of action was to establish soil water measurement (capacitance measurement) in these blocks and to monitor the plant water status with the help of a pressure bomb. It is then continuously monitored and compared with the vineyard’s phys ical condition during regular site visits. The irrigation (or non-irrigation) of these blocks then takes place according to the recommendation of the viticulturists. Dr Myburgh also suggested that flow meters be installed so water applications can be accurately calculated. uniWines Vineyards acquired a pressure bomb device and ap pointed a person to record the readings of these blocks. CHALLENGES EXPERIENCED It proved a problem to get the soil water measurement in place using the capacitance meters. The installation was late, only to discover that the meters may have been installed at ineffective drippers. Figure 1 does, however, show how the water scheduling of the Shiraz was performed over the past season. The pressure bomb worked well, but it broke just before Christmas. Fortunate ly, ample useful information had been collected by that point, which resulted in good irrigation decisions in critical phases like berry development. The producers were then advised to follow their standard irrigation practices from Christmas until the har vesting of the blocks. The disease pressure was high throughout the season, which could yet have a negative effect on the wine quality of all grapes.

PHOTO 1. Mechanical winter pruning of Chenin blanc.

TABLE 1. Irrigation system.

Delivery (L/hour)

Spacing (m x m)

Delivery (mm/hour)

Irrigation (mm/week)

Cultivar

System

Chenin blanc

Sprinkler

-

12 x 12

10

50 mm every two weeks

Sauvignon blanc

Drip

2.3

1 x 2.63

0.87

9.17

Cabernet Sauvignon

Drip

4.0

1 x 2.5

1.60

22.40

Chardonnay

Drip

4.0

1 x 2.74

1.46

20.43

Shiraz

Drip

2.3

0.6 x 2.7

1.42

17.04

Merlot

Drip

4.0

1.0 x 2.5

1.60

19.20

Pinotage

Drip

4.0

0.6 x 2.74

2.43

51.09

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WINETECH TECHNICAL YEARBOOK 2022