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A Technical Guide for Wine Producers
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RECENT ARTICLES | WYNBOER HOME
Unconventional cultivation of grapes for juice, rebate wine and distilling wine
Neels Volschenk & Kobus Hunter, ARC Infruitec-Nietvoorbij, Stellenbosch
Key words: viticulture, unconventional, grape juice, rebate wine, distilling wine.
Cultivation of grapes for juice, rebate wine and distilling wine are very important facets of the South African wine industry. However, successful establishment of commercial vineyards requires large capital input. This, together with the high annual production costs, makes profitable production of grapes for juice, rebate wine and distilling wine almost impossible, even in regions such as the Lower Orange River area which may be suitable for mass production. The high costs make it almost impossible for new producers, and especially potential producers from previously disadvantaged communities, to enter this segment of the Viticulture and Wine industry. To address this, a project that investigates alternative cultivation methods with lower establishment and production costs of vineyards for the production of grape juice, rebate wine and distilling wine was initiated on the Eiland Experiment Farm in Upington in 2004. This project is funded by Winetech and the Agricultural Research Council.
A. Establishment of vineyards:
The cost of grafted plant material amounts to approximately 25% of the establishment costs of traditional vineyards for the production of grapes for juice, rebate wine and distilling wine in the Lower Orange River area. To reduce the cost of plant material, Colombar cuttings (approximately 35 cm in length) were collected during pruning from a healthy vineyard with moderately vigorous growth. Most of the cuttings were stored in a cold room after being treated with fungicide. As many producers do not have cold room facilities, some of the cuttings were buried in the ground. This practice is common among producers in the region to store plant material from pruning until the time of planting. The method appears to be equally successful as storing cuttings in a cold room, but it is extremely important that the cuttings do not dry out.
The cuttings were planted in a sandy, silt soil that was ripped 60 cm deep at the end of August 2004. A planting density of 15 cm between cuttings in the row (alternative or more cuttings will be removed at a later stage) and one metre between rows was used. Vines were trellised onto a 60 cm (from the soil surface) Three Wire Hedge trellising system with two moveable foliage wires. To determine the highest survival percentage and the best growth of cuttings, various establishment techniques, such as the use of rooting agents, cuttings with a piece of two year old wood, and cuttings (ñ80 cm in length) that may be tied to the cordon wire at the time of planting, were investigated. Cuttings were first planted in a nursery and the rooted vines were then planted in the vineyard the following year. Cuttings were also planted in combination with grafted vines. The success of the establishment techniques and the growth of the vines are currently being evaluated. Furthermore, a cost analysis is being done for labour input and material.
B. Practices to ensure a crop in the first and second years:
The grapevine is a long term crop and production actually starts three years after establishment only. To address the cash flow problem, several chemical products were applied to Colombar vines in the first and second year after planting to prevent flower clusters from being aborted. The vines are currently being evaluated to determine whether it is indeed possible to obtain a moderate crop in this period.
C. Reduction of frost damage:
Since soil preparation and irrigation may be done at a lower cost on the low lying, fertile soils in the region, these vineyards are commonly used for the production of grapes for juice, rebate wine and distilling wine. In these areas spring frost commonly occurs. The risk of frost damage is increased in this experiment, given the lower type of trellising system used for the vineyards. Three methods to combat frost damage are being investigated, namely:
1) Selection of cultivars and time of pruning. Six cultivars (Chenin blanc, Palomino, Chenel, Cereza, Viura and Villard blanc) will be pruned at two week intervals from the middle of July to middle October to determine whether it is possible to restrict or prevent frost damage through the timing of pruning and cultivar selection, 2) A protective environment around the vines. Various cover crops are being evaluated to determine the extent to which a protective environment may be formed around the vines to reduce frost damage, and 3) Height of the trellising system. Vines are trellised to different heights (in combination with the different cover crops). For all these methods, frost damage is being evaluated and yield as well as grape composition determined.
D. Successful weed control:
The climate of the region and the high density plantings also create favourable conditions for the growth of weeds and weed control may be difficult. Chemical, mechanical and labour intensive methods (e.g. hoeing), as well as combinations thereof, are being investigated to determine the most practically achievable and economically viable methods for successful weed control.
Results will be released as the investigation progresses.
For more information contact Neels Volschenk at volschenkn@arc.agric.za.
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