Emerging foliar and soil‐borne pathogens of leafy vegetable crops: a possible threat to Europe

Abstract

Italy is one of the leading countries for the production and consumption of ready‐to‐eat salads. This has led to a steady increase in the area used over the last decade for the growth of leafy vegetables under intensive systems. The recent new diseases that affect lettuce, wild and cultivated rocket, lamb's lettuce, spinach and basil are reported here: Plectosphaerella cucumerina on wild rocket, endive and lamb's lettuce, Fusarium equiseti on wild and cultivated rocket and lettuce, Myrothecium verrucaria on spinach and wild rocket, Myrothecium roridum on lamb's lettuce, Allophoma tropica on lettuce and Alternaria sp. on basil and rocket are among the new foliar pathogens in Italy. Among the soil‐borne pathogens, Pythium aphanidermatum, Pythium irregulare and Pythium Cluster B2a have recently been isolated in Italy on spinach and Swiss chard, lamb's lettuce and lettuce, while Fusarium oxysporum f. sp. lactucae, which causes lettuce wilt, is gradually spreading to new countries. Some of the new pathogens have been found to be transmitted by seed and typical of tropical climate, and are thus favoured by the increases in temperature linked to climate change. The globalization of markets, climate change and intensive cultivation are among the factors responsible for the proliferation and spread of some of these new pathogens that are ‘alien’ to Italian production systems.