Drivers of Fusarium dispersion in Madeira Archipelago (Portugal)

Abstract

The present study aimed to analyze the possible routes of Fusarium spp. introduction in Madeira between 1990 and 2018 and to elucidate the factors that favored the introduction and settling of this fungus in the Island. Phytosanitary surveys were carried out in several crops and plants imported to Madeira. The isolates of Fusarium spp. were obtained from underground and aerial organs of the plants and cultured on differential media for species identification. Fungal colony and spore morphology were observed under a microscope and identified based on bibliography and dichotomous keys. The phytosanitary analysis for the incidence of Fusarium spp. in plants or crops indicated an increasing trend in the number of fungi, especially between 1990 and 2001. The greatest fungal contamination occurred in the municipalities located in the southern coast of the Island. Most of the contaminated samples were from Portugal (96.9%), while 0.1% to 1.6% samples derived from foreign countries, especially the Netherlands and France. Of 3,246 samples infected with Fusarium spp., 1,212 were from horticultural (37.3%), ornamental (36.9%), tropical and subtropical (16.9%), and temperate plants (9.9%). Fusarium wilt (Panama Disease) caused by F. oxysporum f. sp. cubense occurred in several products imported to Madeira. Other species like Fusarium oxysporum were also detected in several plants and agricultural products, along with Fusarium sp. and Fusarium equiseti. The geoclimatic conditions of Madeira can be suitable for the development and dispersion of these fungi. The trade of cultivars and plants from Portugal and from foreign countries has been an important route of Fusarium introduction in Madeira.