Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/11/2007
Publication Date: 1/5/2008
Citation: Bobev, S.G., Castlebury, L.A., Rossman, A.Y. 2008. First report of Colletotrichum dracaenophilum on Dracaena sanderiana in Bulgaria. Plant Disease. 92:173. Interpretive Summary: Fungi are a very large and diverse group of organisms that cause serious damage to crop and forest plants. Accurate knowledge of the distribution of fungi is important for tracking the movement of these disease-causing fungi. In this research a fungus that infects members of the agave family especially horticulturally important plants was discovered for the first time outside of its center of origin. This pathogen was only recently described but appears to have been moved around the world with its cultivated host and thus poses a threat to the United States. Knowledge of the distribution of plant pathogenic fungi is useful to horticulturalists in importing nursery stock of specialty crops as well as plant regulatory and quarantine officials.
Technical Abstract: In the winter of 2007, severe damage was observed on indoor potted plants of Dracaena sanderiana hort. Sander ex Mast. (“lucky bamboo”) in Plovdiv, Bulgaria, imported from a country of unknown origin. Initially, the internodes of infected stems appeared pale green with yellowish lesions. An upward-spreading necrosis led to a weakness of the stems with wilt and death of the plants occurring within two weeks. Eventually the entire stem was covered with numerous, black, globose to ellipsoid acervuli with sparse, black setae. The causal pathogen was aseptically isolated from stem lesions on potato dextrose agar (PDA) on which it produced fast growing, pale pink colonies. The conidia were hyaline, broadly clavate to cylindrical, 20-34 x 6.7-10.0 µm (avg. 28 x 8.5 µm). The internal transcribed spacer region of the nrDNA was sequenced and deposited as GenBank EU003533. Based on the symptoms on the plant and morphological, cultural, and molecular characteristics, the fungus was identified as Colletotrichum dracaenophilum D.F. Farr & M.E. Palm. Pathogenicity was confirmed by artificial inoculation of healthy plants of D. sanderiana. Stems were inoculated by inserting small mycelial agar plugs (7 d old, PDA) into wounds. After two weeks, pale green lesions started developing on inoculated plants. The specimen from Bulgaria was deposited in the U.S. National Fungus Collections (BPI 877337) with the derived culture deposited as CBS 121453. This is the first report of Colletotrichum dracaenophilum outside of China and the first report of this species in Bulgaria.