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A Technical Guide for Wine Producers
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RECENT ARTICLES | WYNBOER HOME
WYNBOER WORK PROGRAMME FOR AUGUST 1999
1. PLANNING AND PREPARATION
1.1. Short-term
Financial
1.2. Long-term
Irrigation system: The choice of the correct system of irrigation requires thorough planning. Experiment with dripper and micro lines in the field where the system is to be installed. Study the water distribution and take soil samples to determine the water capacity of the soil. (Read article "Riglyne vir die keuse van Mikrospuite" in the July 1992 issue of Wynboer). "Guide as to how to schedule the irrigation can be obtained by means of a computer programme. Contact the nearest Consultation office.
2. VINEYARD PROGRAMME
Snail control: Good control is achieved with bait, providing it is put out immediately before budding when conditions are moist. See Wynboer Work Programme for May. With a high snail population a small strip of actively growing cover crop/weeds may be left to serve as an alternative food source. If snails still occur, bait can be placed in the forks of vines.
Eelworm control: Where nematode infestation and the condition of vines are such that chemical control is economically justified, spring treatment should now be applied. The chemical should be applied during the active growing period of the roots. Special attention should be given to the abstainment period, especially in the case of producing vineyards.
Grapevine mealy bug: Treat infested vines twice at intervals of 14 days. Use high pressure and spray arms and trunks of the infested as well as adjacent vines thoroughly. See Wynboer Tegnies, Nr 92, March 1997 "Benaderings tot die beheer van Wingerdwitluis in die Wes-Kaap" by Dr Allan Schwartz..
Ant control: Apply ant control especially around vines infested with grapevine mealy bug.
Pruning: The pruning of vineyards subject to frost, delayed foliage or shelling should be carried out as close to budding as possible. Such vineyards should be clean and spur pruned in one action.
Delayed foliage: May occur in cultivars such as Cabernet Sauvignon, Ruby Cabernet, Chardonnay, Colombard and Cape Riesling. Where problematic climatic conditions occur and delayed foliage is expected basal buds may be treated with sianeamide about three weeks before normal budding. See Wynboer Tegnies, No 29, November 1988.
Delayed foliage often occurs in young vineyards. The use of sianeamide while developing the young vines gives good results to enchance bud break. See Wynboer Tegnies, No 28, June 1988.
Sianeamide should be applied as a directed spray with a spraygun, rucksack pump, brush or sponge. Where bud break is required, complete covering of the buds is essential. Injudicious use is extremely dangerous to humans. Wear a respirator and protective clothing while applying the poisonous chemical.
Vine planting: See Wynboer Work Programme for July. Keep reserve vines in plastic bags to use later in the season to replace vines that fail to grow.
Trellising: Erection of trellising systems may be started. See the video titled "Wingerdoplei".
Soil preparation: Barren fields which are to be trenched during November/December must be cultivated with a disc harrow after winter. This prevents excessive drying out of the topsoil and the forming of huge lumps. As contractors do not like working on loose surfaces, a cover crop is preferred to barren soil. Do not do any soil preparation on wet soil.
Cultivation: Cover crops should preferably be killed with a systemic herbicide and then flattened. Working in a cover crop with a disc harrow is undesirable as the thick mat of plant material is cut into pieces and the surface of the soil is disturbed, thus stimulating the germination of summer weeds.
With luxuriant growth conditions on fertile soil under intensive irrigation, and where frost does not occur, only a broad band (1,5 m) under the vines should be sprayed with a herbicide and the remaining weeds/cover crop be allowed to grow actively and ripen. This decreases herbicide cost, suppresses the germination of other weeds, a larger quantity of cover crop material is produced and ripe seed is formed for re-establishment.
Fertilising: Fertilisers are usually applied in organic (eg. fowl manure) or anorganic form (eg. LAN). The value of organic fertilisers is limited mainly to poor sandy/stony soil where there is the danger of nitrogen leaching and trace element deficiencies occur regularly. Otherwise anorganic fertilisers can be used.
Important elements: The main macro elements removed by the crop are nitrogen (N), phosphorus (P) and potassium (K). Vines require small quantities of micro elements such as zinc (Zn), manganese (Mn) and boron (B). To produce 10 t/ha grapes the following elements are removed from the soil: N (39 kg), P (7 kg) and K (31 kg). Approximately half the N and P and a third of the K is returned to the soil by means of leaves and canes. Vines thus have a low fertiliser requirement.
Fertilising directives: Nitrogen is used for vegetative growth. N fertilising is determined mainly by the growth of the vines and soil potential. Production level plays a minor role. N analyses are inaccurate.
Deficiencies of phosphorus (P) and potassium (K) are determined accurately by soil analyses. After soil preparation soil analysis can be done every 3-5 years to control the pH, P, K and Na (sodium) levels in the soil. (Read the article "Stikstofbemesting kan meer oordeelkundig na aanleiding van groeikrag geskied" in the December 1989 issue of Wynboer). The results of leaf analysis can be used with soil analysis to fine tune fertiliser programs.
On pH-low soil (pH < 5,5) maintenance liming of 1-2 t/ha annually is recommended. Dolomitic lime is used on soil with a low Mg content. Due to the greater mobility of slaked lime as compared to calcitic and dolomitic lime, it is preferred in established vineyards.
Alkaline problems (Sodium concentration > 100 ppm and resistance R < 350), can be rectified by using gypsum, good quality irrigation water and adequate drainage.
Fertilising programme: A fertilising programme should be drawn up for each block on the farm, but applications should remain practical, to simplify management (eg. 50 kg quantities).
Nitrogen (N) For ideal growth, well-ripened canes with lengths of 900 -1 200 mm without strong side shoot development are preferred. A vineyard with ideal growth and average production requires about 30-40 kg N/ha annually. In the case of higher production levels or higher rainfall areas more nitrogen is applied. Where luxuriant growth conditions occur the N-application is gradually decreased by, for example, omitting the total summer N-fertilising and applying only 15-20 kg N/ha/year after harvesting.
N applications for young trellised vines and older blocks are usually given in three equal installments (after harvesting, four weeks after bud burst, and after berry set) - in April/October/November.
Phosphorus (P) is relatively immovable in the soil and deficiencies are usually corrected during soil preparation. Optimum norms lie between 20 ppm in sandy and 30 ppm in clay soil. For successful cover crop cultivation, the phosphorus content of the topsoil (300-400 mm) must be at least 20 ppm. Vineyards producing an average of 10 t/ha require about 5-7 kg P/ha/year.
Potassium (K) leaches from the soil easily. In high rainfall areas a shortage of Potassium can be rectified by the application of 30 kg of Potassium for every 10 tons of grapes that are harvested. It can also be applied in smaller instalments.
Single fertilisers are preferred to mixtures as nutrient deficiencies vary from block to block. Mixtures always read in the order of N:P:K with the active percentage of nutrients in brackets. The mixture 3:1:5 (38) contains 12,7 % N, 4,2 % P and 21,1 % K.
Micro element deficiencies occur mainly in high rainfall areas in poor sandy/stony soil. Leaf samples taken from berry set to pea-size berry stage (Nov/Dec) can indicate deficiencies/toxicity. Minimum norms for zinc, manganese and boron are: Zn (15 ppm), Mn (10 ppm) and B (15 ppm).
General
3. VITICULTURE CONSULTANTS IN THE VARIOUS KWV DISTRICTS
For viticulture enquiries consult your nearest KWV Viticulture Consultant.
Paarl/Wellington/Tulbagh: Bennie Liebenberg (021) 8073018, 083 455 5197 or Gavin Taylor (021) 8073418, 083 455 5193.
Malmesbury: Johan Pienaar (021) 8870014, 083 309 7637, Nelius van Huyssteen 083 455 5198 or Bennie Liebenberg (021) 8073018, 083 455 5197.
Robertson/Klein Karoo (02351 - 3017): Francois Viljoen 083 309 7626, Briaan Stipp 083 455 5196, Leon Dippenaar 083 455 5194 or Stephan Joubert 083 650 5590.
Bonnievale: Hendrik Myburgh (02351) 3017 or 083 455 5195.
Orange River: Dirk Malan (054) 4612299, 082 495 7999 or Dricus van der Westhuizen 083 309 7625.
Stellenbosch (021- 8870014): Johan Pienaar, 083 309 7637 or Cobus van Graan 082 650 4404.
Worcester (0231 - 72795): Schalk du Toit 083 303 0530, Pierre Snyman 083 455 5191, Anton Roos 083 629 1735 or Hanno van Schalkwyk 083 455 5192.
Olifants River: Dricus van der Westhuizen 083 309 7625 or Nelius van Huyssteen 083 455 5198.
4. OENOLOGY CONSULTANT
Eugene van Zyl can be contacted at 082 577 2758.
5. WINE GRAPE PLANTING MATERIAL
Enquiries regarding planting material can be obtained from KWV's Plant Improvement Division:
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