Diseases of leafy vegetables and herbs in Australia

Intensive production of leafy vegetables and herbs has expanded rapidly in Australia over the past decade. A range of semi-processed baby-leaf lettuce, spinach, chard, various leafy brassicas and herbs such as coriander, basil and parsley have become popular and conveniently-packaged fresh grocery items. Production occurs in soil and hydroponic systems, the latter becoming more common in peri-urban areas, particularly for basil and coriander that are sold with roots attached. Soil systems and mechanical harvesting are more economically viable for lettuce, chard and spinach. Leafy brassicas are grown in both systems. Plant diseases can be a major limiting factor in both soil and hydroponics, being particularly favoured by the short cropping cycles and intensive production with limited crop rotation. Soil-based systems have become reliant upon fumigation to reduce losses due to soil-borne pathogens while water-borne pathogens adversely affect hydroponic crops. Meanwhile a number of foliar pathogens that are seed-borne cause sporadic losses. Given the market requirement specifying unblemished produce and reasonable shelf-life, a significant number of crops that do not meet specifications are turned-in. This paper presents a check-list from crop surveys and disease diagnoses conducted in all major Australian production areas over recent years. It also discusses alternative and preventative management options as well as biosecurity risks associated with seed.