In the winter of 2007, severe damage was observed on numerous indoor potted plants of Dracaena sanderiana hort. Sander ex Mast. (“lucky bamboo”) in Plovdiv, Bulgaria, which were imported from a country of unknown origin. These plants were already in the retail distribution stream. 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 2 weeks. Eventually, entire stems were covered with numerous, black, globose-to-ellipsoid acervuli with sparse, black setae. The fungus was aseptically isolated from stem lesions on potato dextrose agar (PDA) on which it produced fast-growing, pale pink colonies. On the plant and in culture, the conidia were hyaline, broadly clavate to cylindrical, occasionally slightly curved, and measured 20 to 34 × 6.7 to 10.0 μm (average 28 × 8.5 μm). On the basis of the symptoms on the plant and morphological, cultural, and molecular characteristics, the fungus was identified as Colletotrichum dracaenophilum D.F. Farr & M.E. Palm (1). Pathogenicity of the fungus was confirmed by artificial inoculation of healthy plants of D. sanderiana (three replicates). Stems were inoculated by inserting small mycelial plugs from 7-day-old PDA cultures into wounds that were subsequently covered with Parafilm strips. After 2 weeks, pale green lesions started developing on all inoculated plants and the fungus was successfully reisolated. No symptoms were found around the pure agar control wounds. The specimen from Bulgaria was deposited in the U.S. National Fungus Collections (BPI 877337) with the derived culture deposited as CBS 121453. In addition, the internal transcribed spacer region of the nrDNA of this isolate was sequenced and deposited as GenBank Accession No. EU003533. To our knowledge, this is the first report of C. dracaenophilum on potted plants outside of China and is the first report of this species in Bulgaria.
Reference: (1) D. F. Farr et al. Mycol. Res. 110:1395, 2006.
