Citrus Research International

The CRI Citriculture team under leaderships of Dr Paul Cronje harvested the CRI rootstock trail at Komati Croc Valley this week. Thank you to the Komati Fruit Group team for helping to make this possible. Later this year CRI will give feedback to growers of the last two years research that was conducted within the various research portfolios, this will be done at our 13th CRI Citrus Research Symposium at Champagne Sports Resort in the Drakensberg.

The CRI team had a CBS discussion and orchard visit in Nkwaleni on the 11th June. Dr Providence Moyo gave a talk on understanding fungicide resistance in CBS and Dr MC Pretorius gave the farmers some practical considerations for black spot management in his presentation.

Alternaria Brown Spot (ABS) remains one of the most challenging and economically damaging diseases in susceptible citrus cultivars.
In this CRI Podcast discussion, Prof Jacquie van der Waals, Researcher and Programme Coordinator: Preharvest Diseases, unpacks new CRI research aimed at helping growers manage ABS more effectively through improved cultivar screening and smarter disease prediction tools.

The discussion explores:
• why ABS can severely impact export quality and packouts
• CRI’s work on identifying resistant and susceptible cultivars earlier
• the development of reliable inoculation and genetic screening methods
• how the CRI ABS infection risk model helps growers optimise spray timing
• why preventative disease management is critical

A key message from the episode is that by the time visible symptoms appear, infection has already taken place. This makes proactive management and accurate infection risk prediction essential for effective control.
The discussion also highlights how better timing of fungicide applications could help growers reduce unnecessary sprays while still maintaining protection during high-risk infection periods.

🎧 Watch or listen to the full conversation on the CRI YouTube channel: https://youtu.be/0wn3wGbl5pE or Spotify: https://open.spotify.com/episode/2nEAS2yDYoMBj2vBMD5obK?si=6-t8Nrq8TLaxYEwMwY1LXQ

For viewers wanting additional background on Alternaria management and disease risk in citrus, CRI also recommends watching the previous CRI Podcast discussion with Prof Jacquie van der Waals on this topic: https://youtu.be/Kt5P1gV6Kzc

With severe flooding affecting citrus regions across South Africa, growers and packhouses are now entering the critical management phase where decisions made over the next few weeks could significantly impact root health, postharvest disease development and fruit quality and decisions around which fruit should be packed for export.

In this urgent CRI Podcast discussion, Jan van Niekerk, Soilborne Disease Researcher and Portfolio Manager for Disease Management Research, explains what growers should focus on immediately following flooding and prolonged wet conditions.

The discussion covers:
• Phytophthora risk in saturated soils
• the risk of Phytophthora brown rot and sour rot on flood-affected fruit
• why stressed fruit becomes highly sensitive to damage
• orchard and pack house sanitation measures that cannot be ignored
• handling flood-affected fruit correctly
• phosphonate application considerations
• critical packhouse management adjustments

A key warning from the episode is that many disease problems caused by flooding may only become visible weeks or months later if conditions are not managed correctly now. Fruit decay risks, especially brown rot and sour rot, also need to be considered carefully before fruit is packed and exported.
For growers and packhouses currently dealing with wet orchards, stressed trees and flood-affected fruit, this discussion is highly relevant and time-sensitive.

Watch or listen to the full conversation on the CRI YouTube channel: https://youtu.be/vEFMhg46NeU or Spotify: https://open.spotify.com/episode/0NFT46BvZC6yiKgX3znJIP?si=vErZtjYcTBSPptjaD5iwgg

CRI Members should also read Cutting Edge No. 440 for more information.

Contact your local CRI area extension manager for further support: https://www.citrusres.com/cri-staff-directory-public/

Do you know where your citrus trees come from?

Every productive orchard starts with certified, disease-free propagation material. The Citrus Improvement Scheme (CIS) plays a critical role in protecting South Africa’s citrus industry by ensuring that nursery trees are true-to-cultivar and free from harmful pests and diseases.

Watch the full open video to understand how CIS ensures certified, disease-free propagation material and why nursery certification matters.

The full video on the Citrus Improvement Scheme is on the CRI website: https://www.citrusres.com/citrus-improvement-scheme-explained-ensuring-certified-disease-free-citrus-trees/

For more information, please contact the CRI Nursery Advisory Service or your area’s CRI Extension Officer.

Almost at the end of the CRI Production, IPM & Disease Management workshops 2026, despite the floods causing havoc in certain citrus production areas, citrus farmers and industry specialists still attended these informative workshops, providing valuable information and research based talks focussing on citriculture, integrated pest and disease management. . Thank you to all our sponsors as well for their contribution towards these workshops

Do you know where your citrus nursery gets its rootstock seed from?
This graphic highlights just one part of the Citrus Improvement Scheme.

Watch the full open video to understand how CIS ensures certified, disease-free propagation material and why nursery certification matters.

The full video on the Citrus Improvement Scheme is on the CRI website: https://www.citrusres.com/citrus-improvement-scheme-explained-ensuring-certified-disease-free-citrus-trees/
For more information, please contact the CRI Nursery Advisory Service or your area’s CRI Extension Officer.