The occurrence of Fusarium spp. in green Asparagus officinalis L. spears

Due to changes in the climate and the existence of a wide range of Asparagus officinalis L. cultivars, it is necessary to identify their suitability for cultivation in Poland and investigate their susceptibility to infection by the most common pathogens. The identification of the species composition of fungi of the Fusarium genus found in green spears of edible A. officinalis cultivars and the factors contributing to their occurrence will enable the effective protection of these crops. The study was conducted on seven A. officinalis cultivars bred in different countries, which were dioecious cultivars with male and female specimens: ‘Ariane’ (Germany), ‘Cipres’ (France), ‘Eposs’ (Germany), as well as cultivars with male specimens only: ‘Andreas’ (France), ‘Gynlim’, ‘Grolim’ (Netherlands), and ‘Hannibal’ (Germany). The analysis of the composition of the fungi isolated from the green A. officinalis spears showed that most of the isolates belonged to the Fusarium genus (F. culmorum Wm.G. Sm., F. equiseti (Corda) Sacc., F. oxysporum Schltdl., F. proliferatum (Matsush.) Nirenberg ex Gerlach & Nirenberg, F. solani (Mart.) Sacc., and F. fujikuroi Nirenberg). Other fungal species (Alternaria, Botrytis, Cladosporium, Penicillium, and Stemphylium) were rarely isolated. The majority of the Fusarium genus isolates came from the spears of the ‘Ariane’ and ‘Eposs’ cultivars showing disease symptoms and from the spears of the ‘Grolim’ cultivar without showing disease symptoms. The fungi of the Fusarium genus colonised both the spears with and without disease symptoms, but there were always more isolates on the ones with disease symptoms. Fungi of the Fusarium genus occurred more often in the epidermis than in the parenchyma. F. oxysporum was the dominant fungus in the A. officinalis spears under analysis. The number of fungi isolates of the Fusarium genus collected from the green A. officinalis spears tended to increase at the consecutive harvest dates, which means that the spears harvested at the latest date (late June) were the most heavily colonised by fungi. All of the fungi isolates of the Fusarium genus collected from the spears exhibited pathogenicity against A. officinalis plants.