Guidelines for the preparation of table grapes in SA for export 2025/2026_ND

The thinning process can take up to five days to complete. Therefore, the decision about which gibberellic acid concentration to apply should be informed by the temperature forecast for the five days after the planned thinning date. Don’t remove leaves before the thinning application. The gibberellic acid doesn’t necessarily need to come into direct contact with the bunches, but it’s essential to wet the vines thoroughly. The application details for each cultivar were selected to provide the best outcome. Prime ® , Grapaes (Early Sweet ® ), Sugraone (Superior Seedless ® ), Sugratwelve (Coachella Seedless ® ) and Ralli Seedless™ are genetically predisposed to shot berries (incompletely fertilised berries), so the dose and timing have been calibrated to abort shot berries during set. The thinning application must occur during set, after petal fall, when the ovaries are 2–3 mm in diameter. Trimming Bunches are trimmed to obtain the desired shape. Trimming is typically performed in conjunction with thinning and involves the removal of points and abnormally protruding laterals. Bunches should weigh 500–800 g. A looser bunch of 400–500 g is preferred for punnets. Bunch removal or crop control Bunch removal is the term growers use to refer to the process for optimising the crop load per vine for a given cultivar. The correct crop load is essential for the eventual success of table-grape production. Unwanted bunches should ideally be removed as soon as possible after set, leaving only the optimal number of bunches. These remaining bunches receive the greatest benefit from a smaller crop at an early stage and can develop larger berries with better colour and taste. In practice, it may be challenging to determine which bunches will develop the best shape when assessing them just after set. Therefore, bunches are usually only removed when berries are 5–7 mm in diameter. A preliminary bunch removal before flowering is recommended to improve set in some fertile cultivars, such as Sugrathirteen (Midnight Beauty®) and IFG Ten (Sweet Globe™). Too many bunches can dilute carbohydrate and nutrient levels, thereby increasing the likelihood of excessive shatter. The golden rule is to allow only one bunch per shoot to flower. The recommendation is to have the crop load plus 25% bunches in flower. Leaf removal (leaf pulling) Removing some of the lower leaves on a shoot will improve air circulation and light penetration, prevent chafing of berries, and facilitate better penetration of plant growth regulators and crop protection products. Vine leaves begin contributing carbohydrates when they are approximately one-third of their final size. They photosynthesise maximally when they are fully grown. Thereafter, photosynthesis declines over the following approximately 90 days, until the leaf no longer contributes carbohydrates. Therefore, the contribution of leaves in different positions on shoots to photosynthesis changes during the season. At véraison, the leaves on the middle third of the shoots contribute the most to carbohydrate accumulation.

8 SATI GUIDELINES FOR THE PREPARATION OF TABLE GRAPES IN SOUTH AFRICA FOR EXPORT