Farmer's Weekly (South Africa)
COVER ‘We don’t do anything fancy. We adapt’ – table grape contest winner
The winner of this year’s table grape competition in the Olifants River region, Morné Paxton, spoke to Glenneis Kriel about shade nets and choosing the right grape varieties for export.
The farm Uitkyk has been one of the top three producers in the Olifant River’s annual Table Grape Block Competition every year for the past seven years. Moreover, it has taken first place twice, this year with a block of Red Globe planted in 2003.
Farm manager Morné Paxton says there is no secret to their success. “We don’t do anything fancy. We try to get the basics right, from the planting until the harvesting of the vineyard, and we pay attention to detail, carrying out the right practice at the right time.”
Production practices are also guided by what is happening in terms of market and climatic conditions. “Instead of just carrying on as usual, we’re adapting our practices in case the climatic conditions associated with the past three years’ drought and water shortages become the new norm,” he says.
The farm, near Klawer in the Vredendal district in the Western Cape, belongs to Frikkie and Arend Adriaanse, and has 50ha under wine grapes, 20ha under potatoes, 10ha under tomatoes and 42ha under table grapes, of which 10ha are under nets.
Flat-roofed shade nets have been used since 2012 to protect table grape vineyards against the strong easterly wind that rages in the area from August to December each year. Wind damage during these months results in uneven flowering and fruit set, which in turn lead to uneven ripening and berry sizes. Additional pruning and thinning of bunches are used to overcome this problem, but this has become too expensive due to rising labour costs, according to Paxton.
The shade nets not only protect the vineyards against wind damage, but promote the production of uniform grape bunches, which helps lower labour costs. The environment under shade netting is also warmer and more humid, resulting in more vigorous growth. In addition, the vines require less fertiliser, but their water requirement has so far been found to be similar to that of vineyards planted outside.
According to Paxton, farmers should become more proactive about fungi and insect management, as these organisms benefit from the same environment that allows the vines to thrive.
The side nets are stronger than those on the roof, as they have to withstand the full force of the wind, whereas the wind merely blows over the surface of the roof. The shade factor of the side net is 40%, and that of the roof 20% to allow more light through. The plan is ultimately to cover the entire area under table grape production with nets.
Whereas theft is the greatest challenge for producers who farm near towns, Paxton’s greatest concern is maintenance.
“Once installed, you need to inspect the nets regularly to identify tears, holes and breaks before they turn into more serious problems. Most of these can be fixed by our own staff with a needle and thread. Care should be taken to replace cables with the right ones, as these drastically affect the stability of the structure as a whole,” he says. Nets add about R200 000/ha to vineyard establishment costs, so Paxton advises farmers to employ a reputable professional to install them properly. The structure can last for many years when installed correctly, although the nets might have to be replaced every five to eight years.
Paxton has decided to use only Ramsey and SO4 (Selection Oppenheim) rootstocks in future, as these can withstand the drought and the effect of water shortages better than Paulsen and Richter rootstocks can.
When new vineyards are planted, varieties are selected according to market demand, ease of production, and their ability to produce high volumes of uniform bunches under the farm’s climatic and soil conditions. The availability of water and the varieties’ water requirements are also considered.
The farm does not follow a set vineyard replacement, but underperforming vineyards are replaced when the budget allows.
“Vineyards producing economically viable volumes of varieties that are in demand may be kept for up to 20 years or even longer, whereas those that are struggling to thrive, and varieties that are no longer in great demand, may be replaced after five years,” Paxton says.
Over the past three years, the area under table grapes has been expanded by 5ha to 10ha a year. Another 10ha will be established this year, of which 50% will replace wine grapes, and the rest will be established on virgin soil. Only early-red varieties
are planted, as later varieties suffer colouration problems because of the warm climatic conditions from mid-January to February. Later-green and black varieties, for which colouration is not a problem, are chosen to extend the picking season, which in turn allows the farm to use labour more efficiently and spread market risks.
“We prefer Sun World’s Sugra varieties. Although they’re expensive, they are hardy and perform well in our temperate winters and warm summers. In addition, production of these varieties isn’t highly labourintensive,” Paxton says.
Seeded varieties, such as Dan Ben Hannah and Red Globe, are still produced, as the farm has found a niche for these grapes in Malaysia and Indonesia. The majority of the other varieties are sold to the Middle East, Far East and Canada.
“We try to export our grapes to the best market possible for each cultivar and time of season,” Paxton says.
They are investigating the fixing of currency early in the season to alleviate the impact of currency fluctuations on prices, but the drawback of this is that it takes longer to get paid. Moreover, the practice may backfire if the rand weakens.
“The best option would probably be to fix the currency for only a part of the harvest,” says Paxton.
Grid soil analysis results are used to rectify soil nutrient balances before new vineyards are planted. The soil is treated with Herbifume (active ingredient metamsodium) at least six months before planting to destroy soil-borne disease that might negatively affect vineyard production.
Paxton prefers a gabled to a flat trellis system as it creates easier working conditions. Vine runners can also be trained onto the wires at an earlier stage, which helps prevent wind damage. Drip irrigation is used as it is more water-efficient than microirrigation and produces fewer weed problems. The drippers are spaced 0,6m apart and have a delivery rate of 2ℓ/h.
Drippers have also been installed between rows in the roof of the trellis system, where they are spaced 1m apart and deliver 2ℓ/h. These create a cooler microclimate and force roots to the middle of the row, creating more resilient vines, according to Paxton.
The fertigation programme, developed by a consultant, is based on the age and the developmental phase of the vines, as vines have different nutritional requirements at different times of production.
INDIVIDUAL CRATES CAN BE TRACED TO SPECIFIC PICKERS
Soil probes that take readings every 30cm to a depth of 1,2m are used to guide irrigation decisions and maintain required moisture levels. While readings are updated hourly, Paxton still physically checks the soil and vines to ensure they are not suffering from water or drought stress.
As the soil on Uitkyk is fairly saline, calcium nitrite is the preferred calcium source due to its ability to break down salts and add nitrogen. It is applied weekly from the budding stage, and tapered off as harvesting approaches. Leaf analysis is taken regularly to identify nutritional shortages, and gypsum is used as one of the sulphate sources.
The wheat rye hybrid triticale is planted annually between rows as a cover crop to reduce competition with weeds. The crop is cut twice a year and the cuttings thrown on the vine rows as mulch to reduce evaporation, heat up the soil early in the season, and create a habitat for beneficial organisms.
Vineyards are also pruned in summer to ease winter pruning.
“The goal with summer pruning is to improve light penetration and air movement, as well as spread out labour per block between summer and winter,” Paxton says.
Approximately 40% of the canes are removed during summer pruning to leave enough to compensate for wind or other natural damage that may occur later. Winter pruning is left as late as possible, usually the end of July, to reduce environmental risks, as occurred last year when the region suffered a heatwave in June; heatwaves are associated with uneven budding.
Bunch management is done immediately after fruit set. Depending on the variety, about 20% more bunches are left on the vines than the tally for the final harvest. Once the grapes are ripe, they are picked early in the morning and sent to the farm’s packhouse, ideally within 15 minutes of being picked.
Picking crates are tagged and farmworkers carry scanners with radio frequency identification and GPS to allow full traceability.
“The system, ADAGIN Technologies, was developed by one of the owners’ sons, FG Adriaanse, and allows us to monitor the quality of our grapes and identify weaknesses in the vineyard as well as in the picking teams. If something goes wrong in the market, we can trace the grapes back to specific vines,” Paxton says.
Information generated via the tags helps the farm to measure and improve production efficiency.
Individual crates can also be traced to specific pickers, so added training can be given to those who might be damaging berries during the picking process.
• Email Morné Paxton at firstname.lastname@example.org, or FG Adriaanse at fg.adriaanse@ adagintech.com.