ISOLATION AND IDENTIFICATION OF A NOVEL LEAF NECROTIC PATHOGEN OF VIGNA RADIATA IN PAKISTAN

Mung bean (Vigna radiata L.), a herbaceous, annual legume pulse crop, has high nutritive and clinical values. Amongst the factors damaging to the growth and productivity of this pulse, fungi are the largest and the most important cause affecting the plants at all growth stages. In the present study, a field survey was conducted to isolate the leaf spot pathogen from mung beans. Firstly, the disease symptoms were recorded and infected leaf samples were collected. The pathogen, namely Phoma herbarum, was isolated and identified on the basis of its morphology as well as genetic characterization by nucleotide sequence analysis of the rDNA internal spacer sequence (ITS) gene. The test plants were subjected to detached leaf assay as well as intact plant trials in order to confirm the pathogenic potential of the isolated pathogen. Afterward, Koch's pathogenicity potential of the identified pathogen was confirmed by the occurrence of the same disease symptoms and re--isolation of the same pathogen from artificially inoculated leaves in both trials. To our knowledge, the study represents a novel isolation of P. herbarum as a leaf spot pathogen of mung beans in Pakistan. The pathogen could result in a serious economic impact on mung beans or possibly on other pulses if not managed in time.