Evaluating green technologies to improve table grape quality

CONTACT DETAILS: +27 21 809 3424 / +27 72 776 4708 / vriesf@arc.agric.za
DURATION: One year
LEAD INSTITUTION: ARC Infruitec-Nietvoorbij
BENEFICIARY: The table grape industry

Botrytis cinerea is a common cause for post-harvest decay in table grapes throughout the world. In the South African table grape industry, this fungal disease has been responsible for major economic losses in fruit export markets. Botrytis infection often takes place in the vineyard but typically manifests later, after harvesting and often during cold storage. It is industry norm to store table grapes at -0.5°C before it is moved to local and export markets. Cold storage is used to maintain fruit quality and limit the development of storage diseases.

Bio-active potential against post-harvest fungal disease

Cold storage can successfully slow down the development of Botrytis cinerea, but it is not enough to combat the disease. Instead, cold storage is used in combination with sulphur dioxide (SO²) fumigation. It is common practice to use SO² absorber sheets inside table grape packaging.  Although this method controls post-harvest fungal decay effectively, the chemical can potentially cause damage to the grapes. Furthermore, the standards set for maximum residue limits are continuously changing and the South African fresh fruit export industry is under increasing international pressure to limit the use of chemicals.

Dr Filicity Vries led a project at the ARC Infruitec-Nietvoorbij, which focused on testing safe but environmentally friendly alternative methods to control post-harvest fungal disease. The research team conducted a substantial amount of in vitro testing (Petri plate work) to demonstrate the potential of bio-actives, i.e. essential oils, for use against Botrytis cinerea.

Outcome of study and benefits to industry

  • Research results indicated that bio-actives exhibited antifungal activity against Botrytis cinerea.
  • Funding by the Post-Harvest Innovation Programme was only allocated for in vitro testing.
  • However, further study to develop a technique for use against Botrytis cinerea was initiated. A consortium, consisting of the ARC and the CSIR, is currently funded by the Technology Innovation Agency (TIA) to conduct this two-year project.
  • Evaluation trials conducted at the ARC point to positive outcomes in terms of decay control.
  • If further trials provide successful control of Botrytis cinerea, it will limit chemical usage and provide access to potential new markets.