Postharvest management of table grapes

Achieving top-quality table grapes is complex and is dependent on a series of management choices that start in the vineyard. According to Wietz Botes, the most important of these are the natural environment (soil, topography and climate) in which the grapevines are planted; grapevine vigour (influenced by fertiliser and water application); bunch and shoot manipulations and handling; and harvesting processes implemented.

He also emphasised that in addition to quality, the grapes must be in good condition. Which is affected by choice of packing material and how it affects airflow, preventing condensation, the inclusion of the correct SO2 and humidity management, for example.

SA Fruit Journal DEC | JAN 2022 115 Achieving topquality table grapes is complex, and is dependent on a series of management choices that start in the vineyard.

Marius Huysamer and Johan Fourie provided detail on how to manage the condition of table grapes. In his presentations, Huysamer pointed out that understanding the role humidity plays in determining the overall condition of grapes is very important, but that managing the temperature is where producers can have the biggest influence on the overall performance of their product.

Fourie emphasised the role of the disease triangle (environment, pathogen and host) in disease development. In terms of environment, humidity and temperature are key in disease development and in many instances diseases infect vines in the field, says Fourie. He provided useful pointers for what to consider regarding preharvest and postharvest to best manage disease development during postharvest.

In his presentation Fourie also emphasised the following key points and provided guidelines on how to achieve each:

• Appoint cold-chain specialist/s
• Generate in-house data (e.g. measuring pulp temperature)
• Don’t rely on protocols, they may not suit every scenario
• Do due diligence in terms with packing material

The speakers are available for consultation purposes and may be contacted via the SATI office.

A presentation delivered by Eunice Avenant on 31 August, provided information about resources available directly from SATI: the SATI training videos available to producers via the SATI website (including a section on postharvest management), and the SATI/ARC modular course presented by Huysamer that also includes a section on postharvest management. Visit www.satgi.co.za or contact the SATI office for more information.