Fusarium Consortium Populations Associated with Asparagus Crop in Spain and Their Role on Field Decline Syndrome

Abstract

Asparagus Decline Syndrome (ADS) is one of the main phytosanitary problems of asparagus crop worldwide. Diseased plants and soil samples from 41 fields from three main production areas of Spain were surveyed. Eight <i>Fusarium</i> species belonging to seven species complexes were identified in soils: <i>F. oxysporum</i>, <i>F. proliferatum</i>, <i>F. redolens</i>, <i>F. solani</i><i>sensu stricto</i>, <i>F. equiseti</i>, <i>F. culmorum</i>, <i>F. compactum</i> and <i>F. acuminatum</i>. <i>Fusarium oxysporum</i> was the most prevalent species. Statistical correlation (R² = 88%) was established between <i>F. oxysporum</i> inoculum density and the average temperature of the warmest month. A relationship was also established between three crop factors (average temperature, crop age and <i>F. oxysporum</i> inoculum density) and field disease indices. Significant differences were observed between the distribution of <i>F. oxysporum</i> propagules in white and green asparagus fields. Thirteen <i>Fusarium</i> species belonging to seven species complexes were identified from roots of diseased plants, being <i>F. oxysporum</i> the most prevalent. <i>F. proliferatum</i>, <i>F. oxysporum</i> and <i>F. redolens</i> showed pathogenicity to asparagus and were the main species associated to ADS. <i>Fusarium oxysporum</i> was the species with the highest genetic diversity displaying 14 sequence-based haplotypes with no geographic differentiation. This work contributes to understanding the <i>Fusarium</i> complex associated to ADS for developing accurate integrated disease management strategies.