Type: Radicicolous Fungi; Description: Colonies on agar rose coloured, with white aerial mycelium, tinged pink, floccose. Chlamydospores rare, terminal or intercalary, globose, 6–11 μm in diameter, solitary or catenate. Microconidia none. Macroconidia fusoid, curved, 3–5-septate, 30–55 × 4–5 μm, with a pointed apex and a well-developed foot cell.

Distribution: Auckland, Coromandel, Bay of Plenty, Taranaki, Taupo, Wellington, Gisborne, Hawkes Bay, Wairarapa, Nelson, Westland, Mid Canterbury.; 1st Record: Blair & Morrison (1949).

Significance: Occasionally recorded from forest nurseries (Dick & Dobbie 2002).; Host(s): Buddleja sp., Clianthus puniceus, Cupressus lusitanica, Cytisus scoparius, Eucalyptus fastigata, E. nitens, Humulus lupulus, Passiflora edulis, Phoenix canariensis, Pinus radiata, Sequoia sempervirens, Ulex europaeus.

Notes: The original description of Fusarium by Link (1809), with a single species, F. roseum, was based on elements of different fungi i.e., F. avenaceum, F. sambucinum and F. sporotrichioides, in their current concepts (Wollenweber 1916, Gams et al. 1997). The generic name was later sanctioned by Fries (1832), citing only a malvaceous host, hence determining the application of the name (Domsch et al. 2006). The posterior inaccurate use of the name F. roseum by Snyder & Hansen (1945) for an assemblage of over 20 different taxa which excluded the original concept of F. roseum, rendered the latter name ambiguous and unapplicable (Gams et al. 1997). Thus, a proposal to conserve the name F. sambucinum over F. roseum and earlier synonyms was adopted (Gams et al. 1997, Gams 1999). The lectotype of F. sambucinum is shown in Fig. 64. An earlier, often neglected homonym, F. sambucinum Brondeau (Brondeau 1855) is unavailable because of the conserved status of F. sambucinum Fuckel. The latter name is conserved against all names listed as rejected, and against all combinations of the rejected names (Art. 14.4), as well as against all earlier homonyms (Art 14.10). The current taxonomic position of F. sambucinum Brondeau is unknown; however, with “short, obtuse sporidia” it probably corresponds to a species different than the present concept of F. sambucinum.
Several specimens of F. sambucinum were recently collected from its original host (Sambucus nigra) in Germany, from which seven monosporic cultures, isolated from either ascospores or sporodochial conidia were included here. Their identity was confirmed by morphological and phylogenetic analyses, and sexual crosses with a known F. sambucinum (G. pulicaris) tester strain. To fix the application of the name F. sambucinum to a defined phylogenetic clade, an epitype was selected here (CBS H-25241), and an ex-epitype culture (CBS 151942) was made available to facilitate further research (Fig. 65). The phylogenetic analysis presented in He et al. (2024) indicates CBS 146.95 as “ex-holotype” of F. sambucinum, which is incorrect in every aspect (wrong collection year, collector, country, and substrate).
Fusarium sambucinum resides in the Sambucinum clade of FSAMSC, being morphologically and phylogenetically close to F. agreste, F. seculiforme and F. symmetricum. Shorter macroconidia (av. 28 µm long) differentiate F. sambucinum from F. agreste (av. 34.6 µm long) and differs from F. seculiforme and F. symmetricum by having distinctly apically curved (asymmetrical) conidia, often with a pointy apex, and wider above the median. Additional species commonly compared with F. sambucinum are F. torulosum and F. venenatum (Nirenberg 1995, Leslie & Summerell 2006, Domsch et al. 2007). Fusarium torulosum is genetically unrelated, allocated in the FTSC, and differs by its slow growing colonies, narrower macroconidia, and long chains of chlamydospores (Nirenberg 1995, Leslie & Summerell 2006), while F. venenatum commonly presents slightly larger conidia (av. 44.5 µm long vs 30 µm in F. sambucinum) with up to 9 septa (up to 5 septa in F. sambucinum), and characteristic chlamydospores arranged in curved, terminal chains (Nirenberg 1995, Leslie & Summerell 2006).
Reports of F. sambucinum exist from all over the world, from more than 60 countries in all continents, except Antarctica. This species has been isolated from soil, insects, mammals and human specimens; and it is associated with over 130 plant hosts, either as an endophyte, saprophyte, or inducing canker, die-back or rot symptoms (fruit and root rot, potato dry rot, and storage rot) in more than 100 genera in 45 different families (Farr et al. 2023). However, reports and diseases attributed to F. sambucinum before 1995 should be verified since they could include isolates now identifiable as F. torulosum or F. venenatum (Leslie & Summerell 2006)