First record of Cylindrocladium pauciramosum on Ceanothus in the UK

Abstract

In August 2002, a sample of Ceanothus was submitted to the Central Science Laboratory by the Plant Health and Seeds Inspectorate with symptoms of wilt and shoot blight. The disease was affecting 10% of 200 containergrown plants at a nursery in East Anglia, eastern England; no recent import connection was found. There were numerous dark brown-to-black diffuse lesions on the stems, with profuse white sporulation on the surface. No sporulation was observed on the leaves, and roots were unaffected. Microscopic examination of the fungus revealed characters typical of the genus Cylindrocladium , primarily due to the presence of a sterile appendage on the conidiophore. Examination of the culture on carnation leaf agar, after 7 days at 25 ° C and 12 h near ultraviolet light, revealed that vesicles were clavate to obpyriform (5–12 m diameter; mean 6·85 μ m) with the widest part below the middle on the majority of occasions (77%). Conidia were hyaline, cylindrical, rounded at both ends, one septate with a range of 44–58 × 3·5–4·5 μ m (mean 49·0 × 4·0 μ m). The fungus was identified as Cylindrocladium pauciramosum as described by Schoch et al . (1999). The 5 ′ end of the β -tubulin gene was amplified using primers T1 and Bt2b as described previously (Henricot & Culham, 2002). Comparison of the sequence of the β -tubulin region (accession no. AY880064) with other sequences available in the GenBank database showed it was identical to C. pauciramosum (teleomorph Calonectria pauciramosa ). Koch’s postulates were fulfilled by inoculating young plants with a spore suspension (1 × 10 5