Factors Affecting Development of Alternaria Leaf Spot of Asalio Caused By Alternaria Alternata And Identification of Pathogen

Abstract

The present study was on management of Alternaria leaf spot caused by Alternaria alternata in Asalio. The disease was found to be very severe in all Asalio growing areas causing heavy destruction. The main aim of this investigation was to find out effect of age of the host, inoculum density in Alternaria leaf spot disease development and molecular identification of pathogen. The result shows that the susceptibility in Asalio increased with increase in age on inoculatios of A. alternata. Maximum disease was obtained in the plants ageing 40 DAS with PDI 55.60 per cent. Among the variously examined levels of inoculum concentrations. The two lower concentrations 1 × 101 and 1 × 102 conidia ml-1 exhibited significant difference in the PDI (20.00 and 31.20 respectively) within each other. 1 × 103 and 1 × 104 conidia ml-1 inoculum levels were found to be significantly at par to each other with PDI (39.20 and 40.80 respectively). 1 × 103 conidia ml-1 inoculum concentration was optimum for causing highest level of disease. After inoculation of inoculum 1 × 103 conidia ml-1, typical leaf spot symptoms were observed on the leaves of Asalio plants. Disease severity according to the scale was 39.20%. For molecular identification, 650 bp internal transcribed spacer (ITS) regions (ITS1, 5.8s and ITS2) were amplified through polymerase chain reaction (PCR). The nucleotide sequences from ITS regions of the isolates were submitted to NCBI with GenBank accession numbers MA585375.