Archivio Journal of Plant Pathology

Abstract:

Bermuda grass (Cynodon dactylon) plants showing symptoms of light brown to blackish leaf spots were observed during spring 2012 in the parks and grassy lawns of Lahore (Pakistan). Samples from infected plants were collected and a fungus consistently isolated on potato dextrose agar (PDA) at 28±1°C. The fungus was identified as Bipolaris dactylon (telomorph Cochliobolus australiensis) based on its morphological and molecular features. The pathogen identity was verified by the First Fungal Culture Bank of Pakistan (FCBP) and a culture deposited (accession No. FCBP-1288). In addition, the fungal DNA was isolated and the internally transcribed spacer (ITS) region amplified (White et al., 1990), cloned, sequenced and deposited in GenBank (accession No. HE962033). Sequencing of the ITS region of ribosomal DNA showed a 99.8% nucleotide sequence identity with C. australiensis isolates from Texas (HQ608034) and India (AY923860), respectively. Reproduction of symptoms in inoculated healthy plants fulfilled Koch’s postulates and confirmed pathogenicity. B. australiensis had previously been isolated from infected roots of C. dactylon during a survey in Pakistan (Shahzad and Ghaffar, 1995). However, no details were given of foliar symptoms, nor any pathogenicity test was conducted. Therefore, to the best or our knowledge, this is the first confirmed report of B. dactylon causing a leaf spot on Bermudagrass in Pakistan.