Citrus

According to Jan van Riebeeck’s diary, the first orange trees arrived in the Cape on the ship “de Tulp” from St. Helena on 11 June 1654. By 1661, more than 1 600 orange and lemon trees had been planted in his private garden.

However, it took almost 250 years for South African citrus to start making its mark internationally. In 1907, the shipping of 3 000 cartons of citrus to the United Kingdom marked the first official exports.

Today South Africa is one of the world’s major citrus exporters. This formidable position is no small achievement, given the complexity of the citrus export scene. Producers and exporters have to manage fruit from both winter and summer rainfall areas, meet an enviable array of cultivar requirements, satisfy destination market and regulatory requirements, and cope with the competitiveness of marketers and supermarkets.

The European Union is the biggest consumer of South African citrus, followed by Asia.

The first local citrus producers’ organisation, the South African Cooperative Citrus Exchange (SACCE), was founded in August 1926. Its purpose was to create a single channel market structure that would increase bargaining power and to collect levies from members.

“Only through industry-wide cooperation are we achieving effective, industry specific problem solving.”
Dr Wilma du Plooy, Post-harvest Research and Programme Coordinator (CRI)

Fast facts

  • In 2015, South Africa exported a record 118,7 million 15-kg equivalent cartons of citrus.
  • James Percy Fitzpatrick, the author of Jock of the Bushveld, was a pioneer of commercial citrus farming in South Africa. In 1922, he started marketing citrus grown on his farms in the Sundays River Valley under the Outspan brand.
  • In 1937, Outspan became the trading name for all South African export citrus.
  • In the 1970s and 1980s, the Outspan brand was the focus of an anti-apartheid consumer boycott campaign in Europe and Britain.
  • Citrus is traditionally regarded as winter fruit, but the local season starts in March with easy peelers, mandarins and lemons, and stretches as far into summer as November, when the last oranges are harvested.

Understanding the need for research and development, SACCE invested funds in post-harvest research and, in 1974, opened the Outspan Citrus Centre (OCC) in Nelspruit. As the home of industry-driven research and extension, the OCC set out to improve fruit quality and cultivar availability, and establish Outspan as an international brand name.

Following deregulation in 1998, the industry had to regroup. The Citrus Growers’ Association (CGA) was formed and, in 2001, took over the OCC and transformed it into Citrus Research International (CRI), the institution that now manages almost all citrus research in South Africa.

Some of the citrus industry’s greatest challenges currently arise from food safety concerns, particularly the lowering of minimum residue levels (MRLs). Too often the requirements imposed by supermarkets have no scientific basis and are used for marketing purposes. The biggest concern, however, is disease management. MRLs that are too low allow spores to spread and could undermine sustainable production in the long run.

The South African citrus industry achieves continuous improvement by focusing on three areas:

  • Responsive quality management;
  • Research that addresses industry-determined focus areas; and
  • Technology transfer involving all tiers of production staff.

2019 (R&D currently underway)

  1. Control of Phytophthora brown rot on citrus
    Brown rot may not be a constant enemy in citrus production, but when it does invade it needs to be dealt with on all fronts. A recently completed study is presenting producers and exporters with fresh ammunition.
    Read article: New recruits join the Phytophthora brown rot battle
  2. Fungal degradation on citrus export pallet bases
    Fungi not only wreak havoc with fruit quality and shelf life; they also eat away at the wooden pallets on which cartons of fruit are transported. A recent study, however, has uncovered several solutions.
    Read article: What hides in the woodwork?
  3. Replacement of imazalil on citrus exported to Europe
    A sword hanging over the continued use of imazalil to control green mould on export citrus fruit caused by Penicillium digitatum, has led to the discovery of alternatives that might get the job done even better.
    Read article: Green mould on citrus
  4. Chilling injury of citrus
    Frostbite is not a danger to humans only. When citrus fruit gets too cold, it suffers damage that eat into its market value. This multi-factorial research project set out to find ways to take the bite out of factors that cause chilling injuries.
    Read article: Looking at chilling injuries from all angles
  5. Cold treatment for fruit flies
    When two pests can be controlled with the same treatment, the benefits to the citrus export industry are significant and numerous. New research results suggest such an opportunity exists in the battle against false codling moth and fruit fly infestations.
    Read article: Cold treatment unlocks new fruit fly control options
  6. Fruit Fly post-harvest disinfection treatments
    A study recently proved that the disinfestation treatment for Medfly works equally well for another fruit fly species.
    Read article: What works for Medfly, works for marula fly
  7. Integration of pallet bases and carton designs to improve ventilation of containerised citrus exports
    Ambient loading relieves logistics pressures, but presents cold sterilisation challenges that can only be resolved with packaging that allows optimal airflow.
    Read article: Citrus breathes easier in smarter packaging
  8. FCM Cold treatments
  9. Citrus logistics in cold sterilisation

RESEARCH PROJECTS 2018

  1. Using Carbon dioxide to shorten cold disinfestation treatment for internal pests of citrus fruit destined for Europe
  2. Validation of ambient loading in the False Codling Moth Management System (FMS) for citrus export to the EU
  3. Development of a multiplex PCR technique for differentiation between two lepidopteran larvae with phytosanitary implications

RESEARCH PROJECTS 2014-2017

  1. Non-destructive prediction and monitoring of post-harvest rind quality of citrus fruit using Vis/NIR spectroscopy.
    A project that set out to validate models that predict the rind quality of citrus fruit has confirmed the role that pre-harvest conditions, notably canopy position, play in maintaining the looks of mandarins, oranges and grapefruit.
    Read article:  Keeping up appearances
  1. Detection of FCM in citrus fruit with automatic sorting units.
    Developing cutting-edge technology to detect false codling moth (FCM) infestations as part of a post-harvest systems approach to risk management, FCM is finally running out of places to hide.
    Read article:  Big Brother is watching you FCM
  1. Identifying volatile emissions associated with false codling moth infestation of citrus fruit.
    Healthy and infested fruit have different volatile emission profiles, suggesting that volatiles analysis has great potential as a post-harvest screening method.
    Read article: Big Brother is watching you, FCM (Part Two)
  1. Applying GRAS fumigants for phytosanitary pests.
    It is not often that one post-harvest treatment addresses a variety of challenges. Vapormate®, a fumigant that has been around for at least 90 years, could be one of those exceptions.
    Read article:  Fumigation innovation knocks out phytosanitary pests
  1. Reducing the post-harvest rind pitting of Valencia and Mandarin citrus fruit.
    Rind pitting is a citrus fruit disorder that develops post-harvest during shipping. If its causes can be identified, citrus growers would feel the difference in their pockets.
    Read article:  Plotting the causes of pitting
  1. Effect of irradiation levels on internal and external citrus fruit quality.
    Cold protocol treatments and irradiation are recognised phytosanitary treatments in their own right. Combining them, however, can revolutionise South Africa’s citrus export industry.
    Read article:  A combination that makes all the difference
  1. Investigating cold-storage potential of new mandarin citrus cultivars and the effect of ethylene degreening on rind disorders.
    South Africa’s newest export-quality citrus cultivars have shown that they can withstand sub-zero sterilisation without losing quality. The industry has every reason to be pleased.
    Read article:  New mandarins cope with the cold
  1. Citrus Research Institute post-harvest technical forum extension.
    The transfer of knowledge and skills – known as technology transfer in industry terms – is proving to be a powerful and effective weapon in the citrus industry’s competitiveness arsenal.
    Read article:      Technology transfer yields excellent results
  1. Improved post-harvest essential oil application on citrus fruit through nanotechnology.
    A defining characteristic of nature is its lack of uniformity and predictability. Nanotechnology offers a way to smooth these rough edges in order to harness the power of essential oils to control post-harvest diseases in citrus.
    Read article:  Nature and nanotechnology join forces
  1. Singular and combined effects of post-harvest treatments on viability and reproductive ability of Citrus black Spot (CBS) infections on citrus fruit.
    Pre-harvest prevention remains better than post-harvest cure when it comes to citrus black spot, but this study confirms that pack house treatments do provide a safety net.
    Read article:  Spot the post-harvest difference

RESEARCH PROJECTS 2011-2014

  1. Citrus Cold Chain Forum facilitates technology transfer.
    Perfect fruit perfectly delivered is the holy grail of the fruit export industry. A recently completed project delivered four how-to guides for those who pursue this quest in the citrus cold chain.
    Read article:  Four manuals one mission
  1. Increased lycopene content in the fruit flavedo to reduce chilling injury of grapefruit during cold sterilisation shipments.
    A simple solution brings a blush to the cheeks of pink grapefruit – and solves a chilling export dilemma.
    Read article:  Pretty in Pink
  1. The development and screening of alternative post-harvest disease control products and practices for citrus and pome fruit.
    In the microbiological world, it is the job of ‘good’ microbes to keep the ‘bad’ ones under control. These miniature battles, which rage every day on the surfaces of the fruit we eat, have great potential for post-harvest disease control.
    Read article: Green can also be mean

RESEARCH PROJECTS 2008 – 2010

  1. Packaging solutions for citrus and deciduous fruits
  2. Can GRAS compounds control citrus decay?
  3. Forensic pathology in the citrus supply chain
  4. Optimising imazilil application in the pack houses
  5. Gamma irradiation as a mitigation treatment for false codling moth
  6. South Africa and Spain collaborate
  7. Pre-season workshops improve technology transfer
  8. Illustrated guidelines on citrus postharvest diseases
  9. Understanding the citrus value chain