CODIAEUM RUST

A rust affecting Codiaeum variegatum ('Croton', Euphorbiaceae) importe d into the UK from Ivory Coast in 1978 was originally identified as Ae cidium codiaei H. Sydow. However, studies on germination of spores, pa thogenicity tests and examinations of sori under light microscope and scanning electron microscopy (SEM) revealed that the rust belonged to the tribe Pucciniosireae (a diverse group of mostly tropical microcycl ic rust genera characterised by their stages being telescoped into aec idioid telia). Attention was drawn to the transfer of this Aecidium sp ecies to Dietelia (a member of the Pucciniosireae) following imports o f the disease into the Netherlands from Ghana in 1978. Dietelia codiae i (H. Sydow) Boerema was subsequently confirmed as the causal agent of Codiaeum rust on recent imports into the UK and Italy. It is believed to be distinct from D. emasculata recorded on Breynia, another euphor biaceous host.