The British Species of Cytospora

Molecular phylogeny of Cytospora species associated with canker diseases of fruit and nut crops in California, with the descriptions of ten new species and one new combination

“…The asexual morph is commonly encountered in nature. The pycnidia arise in a stroma embedded in host tissues (Grove 1923), and possess either a single locule or a complex of invaginated walls producing labyrinthine locules with filamentous conidiophores which may be reduced to conidiogenous cells that bear hyaline, allantoid conidia (Adams et al 2006). Pycnidia exude conidia in a yellow, orange to red polysaccharide matrix, a cirrus, via an ostiole (Adams et al 2005, 2006).…”

“…Species diagnosis in Cytospora has traditionally relied on morphological characters of pycnidia/perithecia (Grove 1923), including locule shape/organization and spore dimensions (Spielman 1985), as well as the arrangement of stromatic tissues (Adams et al 2002). This morphological species approach is confounded by many examples of morphological character overlap among species and by the morphological plasticity of pycnidial locules which are affected by the host bark and cambium characteristics (Adams et al 2002, Wang et al 2011).…”

Commodity risk assessment of Ligustrum ovalifolium and Ligustrum vulgare plants from the UK

“… N Pest name EPPO code Group Pest present in the UK Present in the EU Ligustrum confirmed as a host (reference) Pest can be associated with the commodity Impact Justification for inclusion in this list 1 Cytospora pruinosa var. ligustri – Fungi Yes Restricted (only single report from Austria in 1910) Ligustrum vulgare (Shaw et al., 2018 ) Yes No data Doubtful taxonomic identity 1 and uncertainty about impact 2 Phomopsis brachyceras – Fungi Yes Restricted (Belgium, Denmark, Romania) Ligustrum vulgare (Shaw et al., 2018 ) Yes No data Uncertainty about impact 1 The taxonomic identity of the variety is already doubted in Grove ( 1923 ): ‘Strasser places this variety under ‘ Dendrophoma pruinosa ’, which is what Tulasne states to be the spermogone of his Valsa cypri on Ligustrum . Valsa cypri also occurs on Fraxinus , but the British specimens on Ligustrum may not belong to that species’.…”

TWO SPECIES OF VALSA CAUSING DISEASE IN POPULUS

“…Evans (1922, p. 57) mentions it as occurring on poplar in South Africa. Valsa sordida and its pycnidial form Cytospora chrysosperma have often been collected in Europe, and Grove (1923) notes that this Cytospora causes a serious disease of poplars in England. Day (1924), in his description of the bacterial "Watermark disease" of the cricketbat willow in England, states that Cytospora chrysosperma is sometimes of secondary occurrence on trees weakened by the disease.…”

“…Fries (1823). This pathogen, though often merely saprophytic, is the causal agent of the canker disease of poplars first described by Long in 1918 as due to the fungus Cytospora chrysosperma, The perfect and imperfect fruiting stages of this fungus often grow together on the same stem, and taxonomists (such as Diedicke, 1912;Grove, 1923;and others) have claimed that the two stages are of the same fungus, but apparently the relationship was not verified by culture experiments. Single ascospore cultures of Valsa sordida, isolated in the course of this work as described below, have always produced the pycnidial stage known as Cytospora chrysosperma, both on agar media and on sterilized twigs, thus proving the two fruiting forms to be stages of the same fungus.…”