Vinpro Technical Harvest Report 2025

Total leaf wetness hours: September to March (Vredendal)

2500

2000

1500

1000

500 Total number of hours

0

2023/24

2024/25

Growing season

Figure OL 2: Year-on-year comparison of total leaf wetness hours from September to March (2024–2025).

Diseases and pests

Production trends The 2025 harvest began seven days later than usual, largely due to the rapid increase in growing degree day (GDD) accumulation in September, which contributed to much of the strong initial vegetative growth. However, GDD accumulation levelled off significantly in January and subsequently fell below the levels recorded in 2024. Several cultivars experienced a decline in clusters per shoot this season, likely due to the lingering effects of wet spring conditions and suboptimal development of inflorescence primordia from the previous season. In most cases, Chenin Blanc vines produced only one cluster per shoot, while some shoots had no clusters at all. Colombar developed up to three clusters per shoot. Pinotage and Colombar set and developed well, and Sauvignon Blanc was once again average. Cultivars known for poor fruit set, such as Zante Korente, Hanepoot and the Cabernet family produced fewer shot berries than usual (Photo OL 1) . Sufficient accumulation of cold units, ample water supply due to a full Clanwilliam dam, and minor flood damage contributed to optimal conditions throughout the season, which ultimately resulted in good yields.

Downy mildew posed a significant challenge this year due to high humidity in low-lying and flooded vineyards, with evening dew further

exacerbating disease pressure. Flooded vineyards were difficult to access with implements and spray pumps, hindering effective disease and weed control. The production of late cultivars, particularly Ruby Cabernet and Hanepoot, was negatively impacted by downy mildew infections. On Christmas Day, the region experienced an intense heat peak, causing severe sunburn damage to the exposed bunches. Those that had not yet reached véraison were particularly affected, especially in vineyards with north south row orientations. Even in the cooler, late-ripening areas, sunburn damage to the bunches was more significant than usual. The Fruit Fly Bait Project continues to yield positive results, with late-season Colombar and Hanepoot grapes appearing green and healthy at harvest time. Fruit fly damage was observed in vineyards that were prone to delayed ripening, either due to a larger yield or damage to the canopies caused by downy mildew.

VINPRO TECHNICAL HARVEST REPORT 2025 37