Alternaria: Disease Risks, Cultivar Susceptibility & Management - Prof Jacquie van der Waals

In this episode of the Citrus Research International (CRI) Podcast, Prof Jacquie van der Waals, Programme Coordinator for Preharvest Diseases, explains the epidemiology and management of Alternaria Brown Spot and Core Rot - two important diseases increasingly affecting soft citrus.

Jacquie discusses how Alternaria infections begin early in the season, often during first flush and flowering, and how warm, humid conditions drive both disease development and severity. She highlights the role of canopy management, airflow and light penetration in reducing favourable infection conditions, and explains why preventative fungicide applications must be carefully timed and managed to avoid resistance.

She also addresses cultivar susceptibility and shares how CRI is developing rapid bioassays to screen new cultivars before commercial release. Her core message is the importance of early observation and regular “footprints in the orchard,” supported by accurate diagnosis and close communication with CRI extension staff.

About the CRI Podcast
The CRI Podcast features interviews with leading researchers and extension experts from Citrus Research International, highlighting the science and field innovation that keep Southern Africa’s citrus industry competitive and sustainable.