WINETECH Technical Yearbook 2020

TABLE 1. Commercially available Pinotage clones in 2020.

Year selec­ ted

Clones

Origin

Viticulture remarks

Wine remarks

PI 45 Vititec/Bellevue 1972 Average yield and vigour Good quality PI 48 Vititec/Slaley

1972 Average yield and vigour Good quality, widely planted 1976 Not available due to virus infection of source material

PI 50 Meerendal PI 6 Kanonkop PI 7 Warwick

1996 Average yield and vigour Good quality 1996 Average yield and vigour Good quality

2009c, 2009d), rather pointing to vineyard site, vintage, ripeness level, grapevine water status and bunch microclimate as complex drivers to wine quality. Practices such as regulated deficit irrigation (Myburgh, 2011 & Serra Stepke, 2014) and canopy management have shown to improve bunch microclimate and subsequent grape composition and wine quality of Pinotage. Although much remains unknown with regard to the effects of bunch microclimate and key Pinotage qualitative components. The negative impact of management practices which are prone to deliver fruit with heterogeneous maturity, sunburn, extensive shrivelling and general over- ripeness have been documented (Van Schalkwyk & Schmidt, 2009b). Ripening Pinotage is an early ripening variety, with a relatively short growth cycle, ripening up to eight weeks before Cabernet Sauvignon in Stellenbosch, and often avoids several

concentration, occurrence of viruses and Botrytis cinerea resistance. Three clones were selected (PI 45, PI 48 and PI 50) and made available to the industry. Since then PI 50 has been removed due to virus infection of the source material and have been replaced by field selections PI 6 and PI 7 (table 1). Due to its youth, Pinotage clonal material is limited. However, recent DNA sequencing advances have aided the understanding of the genetic make-up of Pinotage and will prove valuable to future breeding programmes (Coetzee, 2018). Traditionally, Pinotage has been cultivated as a bush vine, with local belief that it produces wines of higher quality when cultivated in this way. A long-term investigation into the impact of vine training (bush vine versus vertical shoot positioning – VSP) on Pinotage wine quality displayed no consistent trends regarding this perceived relationship (Van Schalkwyk & Schmidt, 2009a, 2009b,

Planting of Pinotage vines at the foot of Simonsberg, Stellenbosch.

values ranging between 85 and 95, was proposed for highest quality (Van Rooyen et al. , 1984). Grape colour/pigmentation was also identified as a potential ripeness level indicator for Pinotage, but results were not consistent due to the extremely high colour/pigmentation values found in Pinotage compared to other cultivars (Marais & October, 2005). Despite these recommendations, modern era Pinotage producers still mainly use sugar level (°B) to make harvest decisions. Admittedly early studies (Marais et al. , 1979; Du Plessis

heat waves by being harvested before the warmest month (February) of the season. Due to its rapid sugar accumulation, determining the correct ripeness level is critical to avoid over-ripeness. Research regarding Pinotage ripeness levels was first published by Du Plessis and Van Rooyen (1982) in which they proposed a maturity index of °Brix:TA ratio and identified a value of 3.9 as “optimum ripeness” for highest wine quality. In a follow-up work an additional maturity index, namely sugar content (°B) x pH with

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