First record of Ceratocystis fimbriata on Carapa guianensis
New Disease Reports 12/2012; 26:13. DOI: 10.5197/j.2044-0588.2012.026.013
Crabwood or andiroba (Carapa guianensis) is a medium to large tree belonging to the family Meliaceae, widespread in tropical South America, used for timber, furniture, and oil from seeds for cosmetic and ethnomedicinal purposes. Despite its economic importance only one disease caused by Pestalotiopsis macrochaeta has been reported (Halfeld-Vieira & Nechet, 2006). In August 2008, during the course of surveys in a native forest in São João da Baliza municipality in Roraima state, Brazil, dying seedlings of C. guianensis were observed with symptoms of a fungal infection on stems (Fig. 1) and petioles. Only one fungus species was isolated from perithecia present in infected tissue, forming olive brown cultures on potato dextrose agar (PDA). The following morphological features were observed. Perithecia were dark brown, globose, 112-200 μm, neck erect, 431-680 μm, with divergent ostiolar hyphae (Fig. 2A, 2B); perithecial width at the base was 27-34 μm and 20 μm at the apex. Acospores were "hat" shaped, hyaline, 5-7 x 4-5 μm (Fig. 2C). The anamorph corresponded to Chalara with hyaline, cylindrical, catenulate endoconidia with truncate ends, 10-20 x 3.7-5 µm; chlamydospores were pale to dark brown, ovoid, thick-walled, 10-15 x 10-12 µm (Fig. 2D). Based on these morphological characteristics the fungus was identified as Ceratocystis fimbriata (Wingfield et al., 1993). To confirm the identity of the pathogen, the internal transcribed spacer (ITS) region of a representative isolate was amplified using ITS 1 and ITS 4 universal primers and sequenced (GenBank Accession No. JN051277). Ribosomal DNA-ITS sequence data were found to have up to 98% identity with C. fimbriata. To fulfil Koch's postulates, pathogenicity tests were performed in a greenhouse on two-month-old C. guianensis seedlings. Stems were wounded with one superficial puncture with a needle tip, a mycelium plug inserted and the wound covered with Parafilm. A PDA disk was used as control and each treatment consisted of six plants kept under greenhouse conditions. Seven days later the Parafilm was removed and the progress of the symptoms was evaluated. After 10 days, the pathogen was re-isolated from the stem lesions only on plants inoculated with mycelium
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