Plant pathogens – the great thieves of vegetable value

To most vegetable growers, in crop or post-harvest disease invariably rates as the greatest impact on their profitability. Disease “steals” both quantity and quality from production, and necessitates additional cost and time inputs in disease mitigation. Agriculture progressed through the “green revolution” where the answers to pests and diseases could be found in a synthetic pesticide. Along with inputs of high yielding varieties, irrigation systems and synthetic fertilisers, production and quality of crops improved but sustainability issues arose questioning the reliance on chemical approaches for disease control. Environmental and social impacts have resulted in withdrawal from use of important pesticides, and pesticide resistance significantly impacted on treatment efficacy. In current practice integrated disease management systems are required. Consumers still demand low cost, unblemished quality produce, and management must balance the strategic use of pesticides with traditional and novel genetic, cultural and biological controls. For some diseases, innovations in epidemiology and disease prediction, breeding and biotechnology, biological control, new softer chemistries and precision agriculture allow better planning and more strategic and sustainable targeting of a range of controls for disease management. New post-harvest treatments and handling have also enabled products to extend shelf-life, reduce chemical contamination and retain eating qualities. Much remains to be done, many disease pathosystems have no adequate controls, and even where present, costs of implementing effective management can still “steal” significant crop value. The battle for the right of the customer (and not the pathogen) to consume the produce continues.