First report of Ramularia didyma causing a leaf spot on ranunculus (Ranunculus asiaticus) hybrids in California.

摘要

In March 2008, tan-to-brown lesions were observed on the foliage of containerized ranunculus (Ranunculus asiaticus) growing in a greenhouse at a production and retail nursery in coastal San Mateo County, California, USA. Approximately 15% of the approximately 150 mixed shade ranunculus (cv. Bloomingdale) plants had leaf spot symptoms. Symptomatic plants were generally clustered together on two benches, with a double-flowered purple cultivar with picotee markings having the highest disease incidence and severity. Angular to round, necrotic lesions were between 0.25 and 1.0 cm in diameter and were often surrounded by chlorotic tissue. Whitish sporulation was observed on abaxial and adaxial sides of the larger lesions. Morphologically, the fungus matched the description of Ramularia didyma. The sequence of the internal transcribed spacer regions of the rDNA, deposited into GenBank (Accession No. HQ442297), matched Ramularia coleosporii and Ramularia carthami with 96% identity. This is thought to be the first report of Ramularia didyma on Ranunculus asiaticus in California.Digital Object Identifier http://dx.doi.org/10.1094/PDIS-12-10-0892