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.

First report of Globisporangium ultimum causing damping-off of wild rocket seedlings

“…G. ultimum was re-isolated from the infected seedlings, confirming Koch's postulates and the pathogenicity on wild rocket. Despite Pythium damping-off has been previously observed on wild rockets in Italy (Gilardi et al 2018), this is the first report in which molecular identification and Koch's postulates have been accomplished.…”

Effect of increased CO2 and temperature on plant diseases: a critical appraisal of results obtained in studies carried out under controlled environment facilities

“…The efficacy of mancozeb and azoxystrobin against Phoma leaf spot was significantly improved, by 15.3% and 20.6%, respectively, at 800-850 ppm of CO 2 . Penconazole and sulphur were equally effective in controlling zucchini powdery mildew under standard and increased carbon dioxide and temperature values (Gilardi et al, 2017a).…”

Proof of concept for growing lettuce and carrot in a biobased mulch membrane

“…If successful, this biomulch innovation for high-density vegetable plantings could eliminate the need for any of the less effective or risky weed management techniques described previously. And beyond weed control, biomulch use in crops such as lettuce and spinach could help to mitigate crop exposure and incidence of soil-borne plant and human pathogens (Sharapov et al ., 2016; Gilardi et al ., 2018). Moreover, PLA-based biofabric mulches can be manufactured with raw agricultural byproducts such as soybean meal embedded in the fiber matrix.…”