Jacks (1947), in a survey of diseases in glasshouse tomato crops, stated that Cladosporium was the commonest fungus disease affecting the crop. Resistant tomato varieties have since been introduced, but in all cases the resistance has gradually broken down. Improved fungicides, as described by Jacks and Webb (1956d) and Kennelly (1960), have lead to a better control of the disease. In some wet seasons it can become a problem in outdoor crops, especially in the Auckland area.

Description in vitro (on SNA; CPC 13652): Mycelium composed of hyaline to pale brown hyphae, uniform in width, 2 μm diam. Conidiophores arising from hyphae, pale brown, smooth to rough, micro- or macronematous, multi-septate, simple or short branched, straight or sinuous, often strongly curved at the tip, 20–160 μm × 2.5–10 μm, variable in width, sometimes reduced to conidiogenous cell. Conidiogenous cells integrated, terminal and intercalary, proliferating sympodially, polyblastic, with rim-like conidiogenous loci that are darkened and thickened, 1–2.5 μm. Conidia catenate, often forming branched chains, ovoid, obovoid, ellipsoidal, sphaerical, cylindrical, straight or strongly curved, 10–30 × 5–10 μm, 1–4-septate, hila thickened and darkened, 1–2.5 μm diam.

The genus Fulvia is no longer considered a synonym of Passalora as a result of analysis of the type species, Fulvia fulva (≡ Cladosporium fulvum ≡ Passalora fulva), which was recollected and epitypified in this study. Fulvia fulva clusters close to Stromatoseptoria in the phylogenetic analyses (Fig. 1, clade 59; Fig. 3, clade 23). The single-gene trees indicate that both LSU and ITS are able to distinguish this species but rpb2 is more reliable. Fulvia fulva is the causal agent of tomato leaf mould, a disease that affects mostly the leaves of tomato but occasionally also stems, blossoms, petioles and fruit (Butler & Jones 1949, de Wit 1977, 1992, Jones et al. 1997). The interaction between Fulvia fulva and tomato is governed by a gene-for-gene relationship, a characteristic that made this organism an interesting model to study plant-pathogen interactions (de Wit 1981, 1992). The resistance of tomato against Fulvia fulva was genetically determined by the presence of Cf (Cladosporium fulvum) resistance genes of which now five have been cloned. Cf proteins mediate the recognition of effector proteins secreted by Fulvia fulva of which all encoding genes have been cloned (de Wit 2016). Fulvia fulva was once a devastating pathogen of tomato that required treatment with agrochemicals, but since various Cf genes from different wild Solanum species were introduced in commercial tomato cultivars by breeders the pathogen is now under control. Commercially grown tomato cultivars contain up to five different Cf genes (Cf-2, Cf-4, Cf-4E, Cf-5 or Cf-9) (Thomma et al. 2005).

epitype: CBS H-22950, MBT378581, culture ex-epitype CBS 142314